With fall progressing, it brings to mind concerns about potential storm damage to trees. Vicious winds and ice storms, or heavy wet snow, have caused severe tree losses and property damage in the past. The following are some considerations in assessing potential for winter storm damage to trees.
It's often difficult to predict what will happen to trees in landscapes during storms. Healthy trees with no apparent potential problems can drop limbs or fall entirely during unusual weather. But the more common hazards from tree damage occur with trees that are unhealthy or stressed. If a tree has dropped big branches, or shows signs of interior rot when a branch falls, it definitely should be checked.
If a tree has a likelihood of falling, and has a target to hit if it falls, it may be considered a hazard tree.
Checklist for tree hazards:
1) Is there a history of trees falling near your home during bad storms?
2) Do certain trees look unhealthy compared to their neighbors?
3) Has there been construction activity near your trees in recent months or years?
4) Has nearby logging changed the growing conditions and exposed remaining trees to less shade, or stressed them in other ways?
Falling trees:
One very common reason for a tree to fall is because of some type of root problem. Consulting a qualified tree care professional makes good sense if you suspect the presence of a root disease, or if there have been many falling trees in your immediate neighborhood.
Roots that have decayed from fungi may no longer adequately anchor a tree. High winds combined with saturated ground may cause tree failure when root disease has developed.
Unfortunately, finding no signs of root diseases does not mean they are not present. However, close inspections of roots and trunks of fallen trees or drilling suspect trees to look for interior decay can be done by Certified Arborists and/or urban foresters that are familiar with root rots. Professional hazard evaluations are highly recommended for trees located near those that have died, fallen or appear to be dying.
Generally, roots aren't removed when hazard trees are cut down. If a root rot disease has been present, be certain not to replant susceptible trees in the same area.
Tree fall can also be caused by factors other than root rots. Trees may be rocked over by wind when soils are saturated with water. So in addition to root rot problems, there will be other possibilities checked by arborists when evaluating whether a tree is a hazard.
Checking trees for healthy appearance:
If you were to glance around at the trees in a neighborhood, the crowns will range from those with lush, full, healthy appearing foliage to those that have sparse, poor colored foliage. The crown is the part of the tree at the top, the branches that you see silhouetted against sky. The branch pattern and foliage pattern at the top of the tree will be the first area to show symptoms of tree disease. Trees that
With deciduous trees (those that drop their leaves in fall), such as maples, check for crown health when the trees still have all their summer leaves, before leaves begin to drop. The apparent thinning of leaf and twig health at the top of a deciduous tree is much more difficult to detect during and after leaf fall.
Often, a tree in distress will leaf out later than usual in the spring and have smaller leaves than are common. It may also set a very large, bountiful crop of seeds, though seed set needs to be looked at along with other factors in the tree.
Once a large tree begins to show severe symptoms, the situation isn't reversible. There generally are no cures for conifer trees that have root problems or that appear to be dying. Get advice from a qualified professional arborist.
Adapted from "Checking Tree Safety Before Winter Storms" by Mary Robson (Ret.), Area Extension Agent Regional Garden Column October 3, 1999, Washington State University.
Showing posts with label trees. Show all posts
Showing posts with label trees. Show all posts
Saturday, November 21, 2009
Thursday, October 29, 2009
Landscape - Tree Planting Tips
Early November is a good time to plant many deciduous tree species. The following are some tips on tree planting.
LOCATE LOGICALLY - Trees need room to develop root systems underground and branches above ground. Don't plant trees that will grow too large in small areas. Also avoid planting under power or telephone lines or too close to buildings. Site suitability will determine which, if any trees to plant. The designated site may be in the lawn, near a patio, along a street or sidewalk, in a garden, in sun or in a shaded spot. Soils may be clay, sandy, saline, compacted, wet or dry, gravelly or even full of old building rubble. Whatever the situation, you will need to determine if the site is suitable for growing a healthy tree. Consider planting for energy conservation. Deciduous trees will shade the west, south and east sides of the home in summer, and evergreen trees along the west and north edges of the lot will provide winter windbreaks.
CHOOSE CAREFULLY - For what reasons are you planting the tree? You may want privacy, increased property values, a windbreak, shade, fall color, flowers, fruit or a bird habitat. Perhaps you want to create a sound barrier. Combine this information with knowledge about the site.
This is a good time to visit your local Cooperative Extension agent. You'll want to consider that fast-growing trees often are weak and subject to storm damage. Think about the mature size and shape of trees and learn whether their roots might invade sewer lines, lift and crack sidewalks or make bumpy lawns. Learn which trees are likely to harbor insects or diseases.
DIG DILIGENTLY BUT CAUTIOUSLY - Before digging, contact your utility company to mark the location of any underground lines. You could be liable for damage done to such lines.
To prepare the site, mark a circle at least 3 times the diameter of the tree's rootball. Excavate the area with a pick and spade. In clay soil, dig to a depth 2-4 inches shallower than the height of the rootball. In sandy soil, dig to a depth equal to the rootball. Leave the bottom of the hole firm and undisturbed. Holes should be saucer shaped.
PLANT PROPERLY - Try to plant trees when the weather is cool, cloudy and humid, but not windy. If you can't plant right away, keep the tree in a cool, shady, protected spot and keep the roots moist. It helps to soak bare root trees and shrubs in a bucket of water overnight before planting. Remove any plastic or metal containers from the rootball. Place the tree upright in the center of the planting hole. If the tree is in a fiber pot, tear off the sides. If the roots of a containerized tree are potbound, "tease out" some of the roots. For balled and burlapped trees, cut any rope tied around the trunk and pull the burlap away. Cut any reinforcement wire, removing as much as possible, but be sure the rootball stays intact. Shovel backfill into the hole; continue until roots are covered and most of the backfill is used. Don't tamp the soil with your feet.
FERTILIZE FRUGALLY! - Don't put fertilizer into the planting hole; it may cause root injury. Next spring, fertilize young trees lightly. Root stimulator solutions have negligible value. You can use them, but they aren't necessary for transplant success.
WATER WELL - Water the soil at relatively low pressure, using the hose or a "bubbler." Let the water, not your foot, settle the soil. If the soil settles below grade, add more backfill. When done, the planting area should be well-soaked and moist backfill should barely cover the top of the rootball. Watering frequency depends on the soil, not the calendar. Dig with a trowel on the edge of the planting area. Soil that feels moist and holds together when squeezed doesn't need water. Overwatering drives air from the soil, causing root suffocation.
PRUNE PRUDENTLY - A newly planted tree needs only minimal pruning. Prune out only dead, diseased or injured branches. Research shows that transplanted trees establish quicker when as much foliage as possible remains. If you do prune, don't use pruning compounds on pruning cuts.
STAKE SENSIBLY - Trees can be staked too tightly or for too long. Don't stake small trees or those not in the wind's path. Large evergreen trees, planted in a windy site, will need staking. To stake,do not use garden hose and wire. Instead run wire through grommeted staking straps or use wide strips of carpeting. This way, the straps, not the wire, passes around the trunk. A year of staking usually is sufficient. Rigid staking of a tree is counterproductive; research shows trees don't develop normally if they're not allowed any sway.
MULCH MEANINGFULLY - A forest tree provides its own mulch with several inches of leaves on the ground. We can imitate this by mulching the planting area with 3 to 4 inches of wood chips, chunk bark, straw, pine needles or shredded leaves. Don't use plastic beneath the mulch; water or air can't penetrate it. Fabric-type weed-barriers are preferable. One thing you won't see in the forest is manicured lawns around a tree. Research shows that newly planted trees are at a disadvantage when they must compete with grass for water, air and nutrients. Keep grass from the planting area for at least one year. If you mulch around trees, instead of planting grass, you also prevent possible trunk damage by lawn mowers or string trimmers.
Adapted from "Ten Commandments of Tree Planting" By Robert Cox, Colorado State University Cooperative Extension agent, horticulture http://www.colostate.edu/Dept/CoopExt/4DMG/Trees/command.htm
LOCATE LOGICALLY - Trees need room to develop root systems underground and branches above ground. Don't plant trees that will grow too large in small areas. Also avoid planting under power or telephone lines or too close to buildings. Site suitability will determine which, if any trees to plant. The designated site may be in the lawn, near a patio, along a street or sidewalk, in a garden, in sun or in a shaded spot. Soils may be clay, sandy, saline, compacted, wet or dry, gravelly or even full of old building rubble. Whatever the situation, you will need to determine if the site is suitable for growing a healthy tree. Consider planting for energy conservation. Deciduous trees will shade the west, south and east sides of the home in summer, and evergreen trees along the west and north edges of the lot will provide winter windbreaks.
CHOOSE CAREFULLY - For what reasons are you planting the tree? You may want privacy, increased property values, a windbreak, shade, fall color, flowers, fruit or a bird habitat. Perhaps you want to create a sound barrier. Combine this information with knowledge about the site.
This is a good time to visit your local Cooperative Extension agent. You'll want to consider that fast-growing trees often are weak and subject to storm damage. Think about the mature size and shape of trees and learn whether their roots might invade sewer lines, lift and crack sidewalks or make bumpy lawns. Learn which trees are likely to harbor insects or diseases.
DIG DILIGENTLY BUT CAUTIOUSLY - Before digging, contact your utility company to mark the location of any underground lines. You could be liable for damage done to such lines.
To prepare the site, mark a circle at least 3 times the diameter of the tree's rootball. Excavate the area with a pick and spade. In clay soil, dig to a depth 2-4 inches shallower than the height of the rootball. In sandy soil, dig to a depth equal to the rootball. Leave the bottom of the hole firm and undisturbed. Holes should be saucer shaped.
PLANT PROPERLY - Try to plant trees when the weather is cool, cloudy and humid, but not windy. If you can't plant right away, keep the tree in a cool, shady, protected spot and keep the roots moist. It helps to soak bare root trees and shrubs in a bucket of water overnight before planting. Remove any plastic or metal containers from the rootball. Place the tree upright in the center of the planting hole. If the tree is in a fiber pot, tear off the sides. If the roots of a containerized tree are potbound, "tease out" some of the roots. For balled and burlapped trees, cut any rope tied around the trunk and pull the burlap away. Cut any reinforcement wire, removing as much as possible, but be sure the rootball stays intact. Shovel backfill into the hole; continue until roots are covered and most of the backfill is used. Don't tamp the soil with your feet.
FERTILIZE FRUGALLY! - Don't put fertilizer into the planting hole; it may cause root injury. Next spring, fertilize young trees lightly. Root stimulator solutions have negligible value. You can use them, but they aren't necessary for transplant success.
WATER WELL - Water the soil at relatively low pressure, using the hose or a "bubbler." Let the water, not your foot, settle the soil. If the soil settles below grade, add more backfill. When done, the planting area should be well-soaked and moist backfill should barely cover the top of the rootball. Watering frequency depends on the soil, not the calendar. Dig with a trowel on the edge of the planting area. Soil that feels moist and holds together when squeezed doesn't need water. Overwatering drives air from the soil, causing root suffocation.
PRUNE PRUDENTLY - A newly planted tree needs only minimal pruning. Prune out only dead, diseased or injured branches. Research shows that transplanted trees establish quicker when as much foliage as possible remains. If you do prune, don't use pruning compounds on pruning cuts.
STAKE SENSIBLY - Trees can be staked too tightly or for too long. Don't stake small trees or those not in the wind's path. Large evergreen trees, planted in a windy site, will need staking. To stake,do not use garden hose and wire. Instead run wire through grommeted staking straps or use wide strips of carpeting. This way, the straps, not the wire, passes around the trunk. A year of staking usually is sufficient. Rigid staking of a tree is counterproductive; research shows trees don't develop normally if they're not allowed any sway.
MULCH MEANINGFULLY - A forest tree provides its own mulch with several inches of leaves on the ground. We can imitate this by mulching the planting area with 3 to 4 inches of wood chips, chunk bark, straw, pine needles or shredded leaves. Don't use plastic beneath the mulch; water or air can't penetrate it. Fabric-type weed-barriers are preferable. One thing you won't see in the forest is manicured lawns around a tree. Research shows that newly planted trees are at a disadvantage when they must compete with grass for water, air and nutrients. Keep grass from the planting area for at least one year. If you mulch around trees, instead of planting grass, you also prevent possible trunk damage by lawn mowers or string trimmers.
Adapted from "Ten Commandments of Tree Planting" By Robert Cox, Colorado State University Cooperative Extension agent, horticulture http://www.colostate.edu/Dept/CoopExt/4DMG/Trees/command.htm
Landscape - Highly Rated Trees for Delaware
The following are some highly rated trees for planting in Delaware.
Paperbark Maple
Japanese Maple
Blue Atlas Cedar
Hinoki Falsecypress
Dawn Redwood
Sourwood
White Oak
Scarlet Oak
Shingle Oak
Bur Oak
Red oak
Japanese Stewartia
Baldcypress
Hedge Maple
Red Maple
Briotti Red Horsechestnut
Shadblow Serviceberry
Heritage River Birch
American Hornbeam
Shagbark Hickory
White Fringetree
American Yellowwood
Ginkgo
Kentucky Coffeetree
Common Witchhazel
American Holly
Golden Raintree
Sweetgum
Cucumbertree Magnolia
Saucer Magnolia
Star Magnolia
Sweetbay Magnolia
Blackgum
Norway Spruce
Sawtooth Oak
Willow Oak
Japanese Pagodatree
Japanese Snowball
Japanese Tree Lilac
Littleleaf Linden
Chinese Elm
Zelkova
Information from Pennsylvania and Delaware: Tree Species Rating and Valuation Guide; Penn-Del Chapter ISA
Paperbark Maple
Japanese Maple
Blue Atlas Cedar
Hinoki Falsecypress
Dawn Redwood
Sourwood
White Oak
Scarlet Oak
Shingle Oak
Bur Oak
Red oak
Japanese Stewartia
Baldcypress
Hedge Maple
Red Maple
Briotti Red Horsechestnut
Shadblow Serviceberry
Heritage River Birch
American Hornbeam
Shagbark Hickory
White Fringetree
American Yellowwood
Ginkgo
Kentucky Coffeetree
Common Witchhazel
American Holly
Golden Raintree
Sweetgum
Cucumbertree Magnolia
Saucer Magnolia
Star Magnolia
Sweetbay Magnolia
Blackgum
Norway Spruce
Sawtooth Oak
Willow Oak
Japanese Pagodatree
Japanese Snowball
Japanese Tree Lilac
Littleleaf Linden
Chinese Elm
Zelkova
Information from Pennsylvania and Delaware: Tree Species Rating and Valuation Guide; Penn-Del Chapter ISA
Saturday, October 17, 2009
Landscape - Avoid Tree Wrapping
The following is a short article on why to avoid tree wrapping.
Tree wrapping, or wrapping the trunk of young trees after transplanting, is not recommended. In the past, wrapping was done on fall transplants in order to reduce sunscald and frost cracks. However, replicated studies have shown that wraps are not a deterrent to these problems. Wrapping can actually create problems by reducing photosynthesis (because young stems contain chlorophyll), and increasing potential pest attack from borers and certain diseases. The best benefit from wrapping is protection from chewing rodents. For this purpose, it should be in place only during the dormant season.
Information from Steven K. Rettke in the October 10, 2002 edition of the Plant and Pest Advisory, Landscape, Nursery, and Turf Edition from Rutgers University http://njaes.rutgers.edu/pubs/plantandpestadvisory/2002/ln1010.pdf
Tree wrapping, or wrapping the trunk of young trees after transplanting, is not recommended. In the past, wrapping was done on fall transplants in order to reduce sunscald and frost cracks. However, replicated studies have shown that wraps are not a deterrent to these problems. Wrapping can actually create problems by reducing photosynthesis (because young stems contain chlorophyll), and increasing potential pest attack from borers and certain diseases. The best benefit from wrapping is protection from chewing rodents. For this purpose, it should be in place only during the dormant season.
Information from Steven K. Rettke in the October 10, 2002 edition of the Plant and Pest Advisory, Landscape, Nursery, and Turf Edition from Rutgers University http://njaes.rutgers.edu/pubs/plantandpestadvisory/2002/ln1010.pdf
Tuesday, September 22, 2009
Landscape - Avoid Tree Staking if Possible
There is considerable controversy over whether or not to stake trees. Certainly, top heavy trees, trees with limited root balls, or trees in heavily exposed or windy areas may need to be staked. However, many trees are staked that do not need to be. The following are some facts about staked versus unstaked trees.
No staking is necessary for newly transplanted trees that can stand by themselves or have branches to the ground. Compared to rigidly staked trees, unstaked trees will: develop a 33% greater basal trunk area; grow 19% less in height; develop a 30% greater trunk taper; develop a stronger, larger root system; develop more uniform xylem to support itself upright; have few or no rubbing or girdling injuries.
Guy wires with rubber hose protectors. Left on more than one growing season. Partial stem girdling. Photo by Andrew Koeser, International Society of Arboriculture, Bugwood.org
Information from the September 3, 2009 edition of the Plant & Pest Advisory, Landscape, Nursery & Turf Edition from Rutgers University http://njaes.rutgers.edu/pubs/plantandpestadvisory/2009/ln090309.pdf
No staking is necessary for newly transplanted trees that can stand by themselves or have branches to the ground. Compared to rigidly staked trees, unstaked trees will: develop a 33% greater basal trunk area; grow 19% less in height; develop a 30% greater trunk taper; develop a stronger, larger root system; develop more uniform xylem to support itself upright; have few or no rubbing or girdling injuries.
Guy wires with rubber hose protectors. Left on more than one growing season. Partial stem girdling. Photo by Andrew Koeser, International Society of Arboriculture, Bugwood.orgInformation from the September 3, 2009 edition of the Plant & Pest Advisory, Landscape, Nursery & Turf Edition from Rutgers University http://njaes.rutgers.edu/pubs/plantandpestadvisory/2009/ln090309.pdf
Wednesday, June 17, 2009
Landscape - Tree Care After Storm Damage.
The following is some information on tree care after damage from severe storms.
Another two weeks of rain, hail, and wind have caused trouble throughout Delaware. Where will it end?? Trees suffering severe injury as a result of these storms aren't always the luck of the draw. Certain tree species are much more susceptible to damage than others. For instance, silver maples, willows, and ornamental pears can suffer considerable damage. Oaks and many evergreens may sustain only light damage.
Other factors that play a part in storm damage include age and maintenance history of the tree. Large old trees, improperly pruned trees, and those trees with narrow crotch angles can be particularly susceptible to damage. Severe injury can reduce the life of a tree. Wounds caused by storm injury can provide an entrance point for decay organisms and insects. Wounds can also disfigure the tree or ruin its intended function.
If your tree has been damaged, carefully examine the extent of damage. Give immediate attention to trees that are hazards to people or property. If a power line is involved, utility company personnel are the only ones who should be working in the area. After the elimination of hazardous situations, individual tree care can be assessed. Unfortunately, assessment is a judgement call with a large gray area. Severe splitting of the main trunk or an injury that removes more than 1/3 of the bark around the tree is a wound that few trees can survive. Broken tree tops are also severe injuries. Injured trees take time to heal. Repair methods are geared toward assisting the tree in healing as quickly as possible.
Most repair work involves pruning. Use correct pruning techniques to minimize the size of the wound and avoid flush cuts. Remove large, uneven stubs by pruning back to an undamaged side branch. Wound dressings are not recommended. Cabling and bracing may be appropriate if the cost involved can be justified. This method of repair does not save trees with extensive structural damage.
Many landscapers can handle work related to minor storm damage, tree care specialist may be necessar for complicated jobs. For minor damage on small trees a landscape with knowledge of proper pruning procedures, access to proper equipment, and desire can handle the job. Severe damage is better left to someone who specializes in this area. When contracting repair work out, both the homeowner and the tree service professional must clearly understand the work to be done and the cost involved. In areas that have received considerable damage, repair professionals may be heavily booked. It may take some time before they can get to a site. It's important to keep people away from potentially dangerous situations until the necessary work is completed.
If tree replacement ends up being your only alternative, select tree species and cultivars with a sturdy reputation. Avoid species noted for being damage in storms - those with weak wood, ingrown bark problems, those with excessive rapid growth, and those with weak and shallow root systems.
Adapted from an article by Sherry Rindels, Department of Horticulture, Iowa State University.
Another two weeks of rain, hail, and wind have caused trouble throughout Delaware. Where will it end?? Trees suffering severe injury as a result of these storms aren't always the luck of the draw. Certain tree species are much more susceptible to damage than others. For instance, silver maples, willows, and ornamental pears can suffer considerable damage. Oaks and many evergreens may sustain only light damage.
Other factors that play a part in storm damage include age and maintenance history of the tree. Large old trees, improperly pruned trees, and those trees with narrow crotch angles can be particularly susceptible to damage. Severe injury can reduce the life of a tree. Wounds caused by storm injury can provide an entrance point for decay organisms and insects. Wounds can also disfigure the tree or ruin its intended function.
If your tree has been damaged, carefully examine the extent of damage. Give immediate attention to trees that are hazards to people or property. If a power line is involved, utility company personnel are the only ones who should be working in the area. After the elimination of hazardous situations, individual tree care can be assessed. Unfortunately, assessment is a judgement call with a large gray area. Severe splitting of the main trunk or an injury that removes more than 1/3 of the bark around the tree is a wound that few trees can survive. Broken tree tops are also severe injuries. Injured trees take time to heal. Repair methods are geared toward assisting the tree in healing as quickly as possible.
Most repair work involves pruning. Use correct pruning techniques to minimize the size of the wound and avoid flush cuts. Remove large, uneven stubs by pruning back to an undamaged side branch. Wound dressings are not recommended. Cabling and bracing may be appropriate if the cost involved can be justified. This method of repair does not save trees with extensive structural damage.
Many landscapers can handle work related to minor storm damage, tree care specialist may be necessar for complicated jobs. For minor damage on small trees a landscape with knowledge of proper pruning procedures, access to proper equipment, and desire can handle the job. Severe damage is better left to someone who specializes in this area. When contracting repair work out, both the homeowner and the tree service professional must clearly understand the work to be done and the cost involved. In areas that have received considerable damage, repair professionals may be heavily booked. It may take some time before they can get to a site. It's important to keep people away from potentially dangerous situations until the necessary work is completed.
If tree replacement ends up being your only alternative, select tree species and cultivars with a sturdy reputation. Avoid species noted for being damage in storms - those with weak wood, ingrown bark problems, those with excessive rapid growth, and those with weak and shallow root systems.
Adapted from an article by Sherry Rindels, Department of Horticulture, Iowa State University.
Landscape - More on Trees and Storm Damage
There has been considerable storm damage to trees in the landscape this year and more can be expected. The following are some points to consider to reduce storm damage to trees in the landscape.
Inventory: By keeping track of trees on your property and their condition, predicting storm failure is much easier. Create a list of "key trees and key problems." Key trees would be those that are most important to the property. Key problems would be those that are most likely to damage or weaken those key trees.
Monitor: Check key trees regularly. When minor damage occurs, correction (such as pruning out damaged material) may prevent it from causing extensive damage throughout the tree. If extensive damage has occurred, immediate corrective action should be applied to prevent further damage.
Proper Pruning: Pruning either corrects problems or creates them. If pruning is done improperly, it can create places for decay to enter and the wound will only increase in extent. Done correctly, pruning wounds should close over naturally, keeping decay from starting and expanding in the wound area. A general rule for pruning wounds: the smaller, the better.
Protection From Mechanical Wounding: Mulching, planting trees in landscaped beds, and even staking can give trees the necessary protection from mechanical injury. Wounds caused from lawnmowers and grass trimmers can promote areas of decay in the tree. Any actions that causes wounds on stems and branches can cause long-term damage in a short time.
Appropriate Species: Using appropriate species in each site is extremely important. Many of the problems that homeowners face could be diminished just by using species that are native to the area or accustomed to the site conditions. For instance, an upland forest tree (such as white pine) will never be healthy and stable if planted in compacted, poorly-drained soils. A tree adapted to moist soils will do poorly in droughty areas.
Best Planting Practices: Planting too deep may be the most common planting mistake that leads to tree failure. Literature is available on proper planting techniques. Most importantly, do not plant the tree too deep. The first set of roots should be just below the soil surface.
Adapted from "Storm Damage to Landscape Trees: Prediction, Prevention, Treatment" by Gary R. Johnson, Associate Professor, Urban and Community Forestry, Ben Johnson, Undergraduate Research Assistant, Department of Forest Resources, University of Minnesota.
Inventory: By keeping track of trees on your property and their condition, predicting storm failure is much easier. Create a list of "key trees and key problems." Key trees would be those that are most important to the property. Key problems would be those that are most likely to damage or weaken those key trees.
Monitor: Check key trees regularly. When minor damage occurs, correction (such as pruning out damaged material) may prevent it from causing extensive damage throughout the tree. If extensive damage has occurred, immediate corrective action should be applied to prevent further damage.
Proper Pruning: Pruning either corrects problems or creates them. If pruning is done improperly, it can create places for decay to enter and the wound will only increase in extent. Done correctly, pruning wounds should close over naturally, keeping decay from starting and expanding in the wound area. A general rule for pruning wounds: the smaller, the better.
Protection From Mechanical Wounding: Mulching, planting trees in landscaped beds, and even staking can give trees the necessary protection from mechanical injury. Wounds caused from lawnmowers and grass trimmers can promote areas of decay in the tree. Any actions that causes wounds on stems and branches can cause long-term damage in a short time.
Appropriate Species: Using appropriate species in each site is extremely important. Many of the problems that homeowners face could be diminished just by using species that are native to the area or accustomed to the site conditions. For instance, an upland forest tree (such as white pine) will never be healthy and stable if planted in compacted, poorly-drained soils. A tree adapted to moist soils will do poorly in droughty areas.
Best Planting Practices: Planting too deep may be the most common planting mistake that leads to tree failure. Literature is available on proper planting techniques. Most importantly, do not plant the tree too deep. The first set of roots should be just below the soil surface.
Adapted from "Storm Damage to Landscape Trees: Prediction, Prevention, Treatment" by Gary R. Johnson, Associate Professor, Urban and Community Forestry, Ben Johnson, Undergraduate Research Assistant, Department of Forest Resources, University of Minnesota.
Tuesday, June 16, 2009
Landscape - Reducing Storm Damage in Trees
After the recent violent storms in Delaware and significant damage in landscapes, I thought it would be good to repost an article on preventing storm damage to trees.
There is no way, except for complete enclosure, to protect trees from all storm damage. Trees are not adapted to worst-case storms -- only to our average wind climate. Listed are several things to minimize the main types of storm damage:
Let trees adjust to the wind environment. Tight staking and guying from the time of planting holds a tree in place while preventing internal adjustment to wind loading. Always stake and tie the tree loosely where the stem can move and bend in the wind. Keep ties in place for a few growing seasons to ensure a well-established root system. Continue to loosen and, eventually, release the ties. Leave the support stakes in place to protect the stem from mechanical damage. After five to seven years, remove all tree support. The tree will continue to grow and adjust to its new environment.
Practice proper pruning techniques by cutting branches before they become larger than 1 inch in diameter. Do not damage the branch collar (Figure 1). The branch collar is part of the stem and, if damaged by poor pruning, provides an avenue of attack into the main stem for pests. Proper pruning minimizes a number of structural problems that occur in association with new wood growth around a pruned branch.
Eliminate co-dominant branches. Prune forked branches and branches that arise opposite each other on the stem early. Cut one side off now to prevent loving the whole tree later if it splits in a storm. In trees with opposite branching patterns (such as ash or maple), proper branch training is essential for a long-lived, storm resistant tree.
Keep trees as healthy as possible with timely watering and proper fertilization. Healthy, vigorous trees adjust more quickly to changes in the environment, are more wind firm and react more effectively to damage.
Do not over-fertilize the tree with nitrogen or over-water the soil. This can increase the crown surface area and/or decrease the rooting area. This type of biological change makes the tree susceptible to storm damage.
Eliminate lopsided crowns. Prune branches to produce a reasonably symmetrical crown. If more than 70 percent of the crown is on one side of a mature tree, consider tree removal and replacement. Guying and bracing branches are last-ditch efforts when a tree has to be saved in spite of itself.
Remove or treat pest problems such as branch cankers to minimize potential damage. Do not over-treat tree hollows. Do not remove decayed wood from hollows unless it falls away in your hands. Cleaning hollows can lead to further internal damage. Cover the openings to hollows to allow the tree to grow over the opening; covering also prevent animals from expanding the hollow and keeps water from running in.
Keep the tree growing upright with one main stem. Prune away branches that compete in height with the main stem. Eliminate branches with tight or narrow crotches.
Install lightning protection systems on historic, rare, specimen or recreational area trees. Consult a qualified arborist or urban forester to ensure adequate design. Lightning protection systems are covered in detail in the section "Lightning Protection Systems."
Continue to promote wind firmness by not over-crowding trees and by proper guying and bracing. A tree must always be able to move in the wind. Do not keep a tree tied into position with tight cables. In a stand of trees, slowly remove trees over a number of years to allow wind firmness to develop in the remain-ing trees.
Information from "Storm Damaged Trees: Prevention and Treatment" by Kim Coder, Professor Silvics/Ecology, Warnell School of Forest Resources, University of Georgia. Go to http://pubs.caes.uga.edu/caespubs/pubcd/C806.htm for the full fact sheet.
There is no way, except for complete enclosure, to protect trees from all storm damage. Trees are not adapted to worst-case storms -- only to our average wind climate. Listed are several things to minimize the main types of storm damage:
Let trees adjust to the wind environment. Tight staking and guying from the time of planting holds a tree in place while preventing internal adjustment to wind loading. Always stake and tie the tree loosely where the stem can move and bend in the wind. Keep ties in place for a few growing seasons to ensure a well-established root system. Continue to loosen and, eventually, release the ties. Leave the support stakes in place to protect the stem from mechanical damage. After five to seven years, remove all tree support. The tree will continue to grow and adjust to its new environment.
Practice proper pruning techniques by cutting branches before they become larger than 1 inch in diameter. Do not damage the branch collar (Figure 1). The branch collar is part of the stem and, if damaged by poor pruning, provides an avenue of attack into the main stem for pests. Proper pruning minimizes a number of structural problems that occur in association with new wood growth around a pruned branch.
Eliminate co-dominant branches. Prune forked branches and branches that arise opposite each other on the stem early. Cut one side off now to prevent loving the whole tree later if it splits in a storm. In trees with opposite branching patterns (such as ash or maple), proper branch training is essential for a long-lived, storm resistant tree.
Keep trees as healthy as possible with timely watering and proper fertilization. Healthy, vigorous trees adjust more quickly to changes in the environment, are more wind firm and react more effectively to damage.
Do not over-fertilize the tree with nitrogen or over-water the soil. This can increase the crown surface area and/or decrease the rooting area. This type of biological change makes the tree susceptible to storm damage.
Eliminate lopsided crowns. Prune branches to produce a reasonably symmetrical crown. If more than 70 percent of the crown is on one side of a mature tree, consider tree removal and replacement. Guying and bracing branches are last-ditch efforts when a tree has to be saved in spite of itself.
Remove or treat pest problems such as branch cankers to minimize potential damage. Do not over-treat tree hollows. Do not remove decayed wood from hollows unless it falls away in your hands. Cleaning hollows can lead to further internal damage. Cover the openings to hollows to allow the tree to grow over the opening; covering also prevent animals from expanding the hollow and keeps water from running in.
Keep the tree growing upright with one main stem. Prune away branches that compete in height with the main stem. Eliminate branches with tight or narrow crotches.
Install lightning protection systems on historic, rare, specimen or recreational area trees. Consult a qualified arborist or urban forester to ensure adequate design. Lightning protection systems are covered in detail in the section "Lightning Protection Systems."
Continue to promote wind firmness by not over-crowding trees and by proper guying and bracing. A tree must always be able to move in the wind. Do not keep a tree tied into position with tight cables. In a stand of trees, slowly remove trees over a number of years to allow wind firmness to develop in the remain-ing trees.
Information from "Storm Damaged Trees: Prevention and Treatment" by Kim Coder, Professor Silvics/Ecology, Warnell School of Forest Resources, University of Georgia. Go to http://pubs.caes.uga.edu/caespubs/pubcd/C806.htm for the full fact sheet.
Landscape - Storm Damage to Trees
Recent violent storms across the state have done significant damage to trees in the landscape. The following is a reprints of an article on types of storm damage to trees.
There are six main types of storm damage to trees:
(1) blow-over, (2) stem failure, (3) crown twist, (4) root failure, (5) branch failure and (6) lightning. Each type is the result of a complex and interactive mix of tree problems and climate.
Blow-Over
With blow-over, the tree is physically pushed over by high winds. Little biological adjustment is available for a tree (or for people) to make to hurricanes, down-drafts or tornado winds. The wind force on the aerial tree portions is too great for the wood structure. Past tree abuse, poor maintenance, pest problems (like fusiform cankers on pine or root rots on hardwoods) predispose the tree to storm damage by weakening the wood architecture.
Stem Failure
Trees do not heal wounds. Trees can only grow over old wounds and seal them off. This results in a tree carrying in its wood every injury it has ever had. These old injury sites -- and the old and new wood around them -- are structurally weaker than normal solid wood. These damaged areas can quickly fail under a constant wind loading and release. Pest damage, weak wood around old wounds, new wounds and failure of the tree to adjust to wind conditions can lead to stem failure under heavy wind loading and release.
For trees with heavy crowns, abrupt wind gusts and calm periods can lead to stem breakage from release. As the wind load is quickly released, the tree moves back into an upright position. If the mass of the crown moves too quickly when released, the inertia of the moving crown may move too far in the opposite direction leading to stem damage and breakage.
Crown Twist
Tree crowns are the leaves and supporting twigs and branches. Trees are never perfectly symmetrical in every direction. Many trees, through past abuse and poor management, have lopsided crowns. More wind loading on one side of the crown than on another produces a twist (torque) on major branches and the main stem. Over time, the twisting effect can be biologically adjusted from within the new wood. Stem twisting will magnify weaknesses around old injuries and the stem will split or branches collapse.
Root Failure
There are two types of tree roots: fine, absorbing roots and woody, structural roots. As their names imply, ab-sorbing roots have a massive surface area but are weak. Structural roots are woody, have a relatively small sur-face area, but are strong. Both types provide anchorage for a tree. The primary roots growing from the bottom of the stem (root collar) play dominant roles in holding the tree upright while conducting water, essential elements and nutrients. If roots are constrained, diseased or dam-aged by construction or -- as the top of the tree becomes larger -- greater stress is put on the roots. Pulled or snapped roots cause trees to fall or lean.
Branch Failure
Branches are poorly attached to the main stem. A branch is stuck on the side of the stem each year by a small layer of stem wood called the branch collar. The branch collar surrounds the branch base. The woody material from the branch enters the stem and turns downward. This structural arrangement allows the branch to be flexible and disposable. The stem can shut off the branch when the branch becomes a biological liability to the tree.
Heavy loading (as during an ice storm) puts great stress on the branch collar area. Over many years, a tree will adjust to this stress, but ice storms or downbursts that occur only rarely will leave the branches unprepared and susceptible to tearing downward along the stem or snapping. The branch collar area can also be weakened by included bark. This material is bark from both the expanding stem and branch. Where the branch and stem expand against each other, bark can be surrounded and overgrown inside the branch collar area. Included bark leads to weaker structure and a place for pest attack. This is why forks (called co-dominant branches) are structurally weak. These weak areas can easily fail in a storm.
Lightning
Lightning damage is a life-threatening situation. Lightning either moves in a narrow line down the branches, stems and roots or along a wide pathway encompassing the entire tree cylinder. Lightning directly destroys tree tissues by electrical disruption and heat. Steam explosions down the stem in a wide or narrow band show where the electrical current has moved through the tree.
Massive root damage can remain unseen. Damage caused by lightning leads to extensive water loss that is also life-threatening. Pests quickly attack a lightning weakened and damaged tree. For example, the Southern pine beetle quickly destroys a lightning struck pine.
Information from "Storm Damaged Trees: Prevention and Treatment" by Kim Coder, Professor Silvics/Ecology, Warnell School of Forest Resources, University of Georgia. Go to http://pubs.caes.uga.edu/caespubs/pubcd/C806.htm for the full fact sheet.
There are six main types of storm damage to trees:
(1) blow-over, (2) stem failure, (3) crown twist, (4) root failure, (5) branch failure and (6) lightning. Each type is the result of a complex and interactive mix of tree problems and climate.
Blow-Over
With blow-over, the tree is physically pushed over by high winds. Little biological adjustment is available for a tree (or for people) to make to hurricanes, down-drafts or tornado winds. The wind force on the aerial tree portions is too great for the wood structure. Past tree abuse, poor maintenance, pest problems (like fusiform cankers on pine or root rots on hardwoods) predispose the tree to storm damage by weakening the wood architecture.
Stem Failure
Trees do not heal wounds. Trees can only grow over old wounds and seal them off. This results in a tree carrying in its wood every injury it has ever had. These old injury sites -- and the old and new wood around them -- are structurally weaker than normal solid wood. These damaged areas can quickly fail under a constant wind loading and release. Pest damage, weak wood around old wounds, new wounds and failure of the tree to adjust to wind conditions can lead to stem failure under heavy wind loading and release.
For trees with heavy crowns, abrupt wind gusts and calm periods can lead to stem breakage from release. As the wind load is quickly released, the tree moves back into an upright position. If the mass of the crown moves too quickly when released, the inertia of the moving crown may move too far in the opposite direction leading to stem damage and breakage.
Crown Twist
Tree crowns are the leaves and supporting twigs and branches. Trees are never perfectly symmetrical in every direction. Many trees, through past abuse and poor management, have lopsided crowns. More wind loading on one side of the crown than on another produces a twist (torque) on major branches and the main stem. Over time, the twisting effect can be biologically adjusted from within the new wood. Stem twisting will magnify weaknesses around old injuries and the stem will split or branches collapse.
Root Failure
There are two types of tree roots: fine, absorbing roots and woody, structural roots. As their names imply, ab-sorbing roots have a massive surface area but are weak. Structural roots are woody, have a relatively small sur-face area, but are strong. Both types provide anchorage for a tree. The primary roots growing from the bottom of the stem (root collar) play dominant roles in holding the tree upright while conducting water, essential elements and nutrients. If roots are constrained, diseased or dam-aged by construction or -- as the top of the tree becomes larger -- greater stress is put on the roots. Pulled or snapped roots cause trees to fall or lean.
Branch Failure
Branches are poorly attached to the main stem. A branch is stuck on the side of the stem each year by a small layer of stem wood called the branch collar. The branch collar surrounds the branch base. The woody material from the branch enters the stem and turns downward. This structural arrangement allows the branch to be flexible and disposable. The stem can shut off the branch when the branch becomes a biological liability to the tree.
Heavy loading (as during an ice storm) puts great stress on the branch collar area. Over many years, a tree will adjust to this stress, but ice storms or downbursts that occur only rarely will leave the branches unprepared and susceptible to tearing downward along the stem or snapping. The branch collar area can also be weakened by included bark. This material is bark from both the expanding stem and branch. Where the branch and stem expand against each other, bark can be surrounded and overgrown inside the branch collar area. Included bark leads to weaker structure and a place for pest attack. This is why forks (called co-dominant branches) are structurally weak. These weak areas can easily fail in a storm.
Lightning
Lightning damage is a life-threatening situation. Lightning either moves in a narrow line down the branches, stems and roots or along a wide pathway encompassing the entire tree cylinder. Lightning directly destroys tree tissues by electrical disruption and heat. Steam explosions down the stem in a wide or narrow band show where the electrical current has moved through the tree.
Massive root damage can remain unseen. Damage caused by lightning leads to extensive water loss that is also life-threatening. Pests quickly attack a lightning weakened and damaged tree. For example, the Southern pine beetle quickly destroys a lightning struck pine.
Information from "Storm Damaged Trees: Prevention and Treatment" by Kim Coder, Professor Silvics/Ecology, Warnell School of Forest Resources, University of Georgia. Go to http://pubs.caes.uga.edu/caespubs/pubcd/C806.htm for the full fact sheet.
Monday, May 18, 2009
Landscape - Anthracnose of Shade Trees
The following is a good article from Rutgers on anthracnose of shade trees. This is a common disease in Delaware. Photos of sycamore anthracnose are shown in the previous post.
Anthracnose of Shade Trees
Anthracnose is a common disease of many shade tree species, particularly sycamore, ash, oak, maple, and walnut. This disease affects foliage as a scorch along leaf margins and veins, and also causes dieback and cankers to form on twigs.
Anthracnose begins its annual cycle in the spring. Small fruiting structures situated on small twigs infected the previous year produce spores. Spores are splashed and carried by wind to infect developing leaves. These diseased leaves develop lesions along veins and leaf margins, causing the tissue to appear “scorched.” In severe cases, leaves soon completely blight and fall from the tree. In some species such as sycamore, trees promptly refoliate in the drier, early summer months. These new leaves are not usually affected by the disease; anthracnose is more severe when temperatures during leaf expansion remain between 55 and 60 F, and when moisture remains on leaf surfaces for long periods of time.
In the twig blight phase of the disease, infected twigs may die back 6 to 8 inches from the tips, and larger cankers may form if infection is severe or if the tree is in poor health. Repeated tip dieback results in clusters of dead twigs called “witches’ brooms,” which are readily apparent as you look at the silhouette of the tree.
To manage anthracnose, improve plant vigor, prune cankers and dead branches, and avoid planting highly sensitive plants. Irrigate in the early morning hours and avoid over-head watering to prevent excessive moisture from remaining on foliage. Since anthracnose does not usually cause serious damage to healthy trees, application of fungicides is recommended only when it is necessary to keep trees as blemish-free as possible.
If desired, some control of this disease can be obtained with foliar applications of fungicides which include Armada, Bacillus subtilis, chlorothalonil, ConSyst, copper, (Badge, hydroxide, oxychloride, salts, sulfate), Junction, mancozeb, neem oil, phosphate (trunk injection), Quali-Pro TM/C WDG, Spectro, SysStar, thiabendazole (trunk injection), thiophanate-methyl, TwoSome (no commercial uses), trifloxystroban, or Zyban.
Information from "Foliar Diseases in the Landscape" by Ann B. Gould, Ph.D., Specialist in Plant Pathology, Rutgers Univerisity in the April 30, 2009 edition of the Plant and Pest Advisory newsletter, Landscape, Nursery, and Turf Edition from Rutgers University. Go to http://njaes.rutgers.edu/pubs/plantandpestadvisory/2009/ln043009.pdf for the full article.
Anthracnose of Shade Trees
Anthracnose is a common disease of many shade tree species, particularly sycamore, ash, oak, maple, and walnut. This disease affects foliage as a scorch along leaf margins and veins, and also causes dieback and cankers to form on twigs.
Anthracnose begins its annual cycle in the spring. Small fruiting structures situated on small twigs infected the previous year produce spores. Spores are splashed and carried by wind to infect developing leaves. These diseased leaves develop lesions along veins and leaf margins, causing the tissue to appear “scorched.” In severe cases, leaves soon completely blight and fall from the tree. In some species such as sycamore, trees promptly refoliate in the drier, early summer months. These new leaves are not usually affected by the disease; anthracnose is more severe when temperatures during leaf expansion remain between 55 and 60 F, and when moisture remains on leaf surfaces for long periods of time.
In the twig blight phase of the disease, infected twigs may die back 6 to 8 inches from the tips, and larger cankers may form if infection is severe or if the tree is in poor health. Repeated tip dieback results in clusters of dead twigs called “witches’ brooms,” which are readily apparent as you look at the silhouette of the tree.
To manage anthracnose, improve plant vigor, prune cankers and dead branches, and avoid planting highly sensitive plants. Irrigate in the early morning hours and avoid over-head watering to prevent excessive moisture from remaining on foliage. Since anthracnose does not usually cause serious damage to healthy trees, application of fungicides is recommended only when it is necessary to keep trees as blemish-free as possible.
If desired, some control of this disease can be obtained with foliar applications of fungicides which include Armada, Bacillus subtilis, chlorothalonil, ConSyst, copper, (Badge, hydroxide, oxychloride, salts, sulfate), Junction, mancozeb, neem oil, phosphate (trunk injection), Quali-Pro TM/C WDG, Spectro, SysStar, thiabendazole (trunk injection), thiophanate-methyl, TwoSome (no commercial uses), trifloxystroban, or Zyban.
Information from "Foliar Diseases in the Landscape" by Ann B. Gould, Ph.D., Specialist in Plant Pathology, Rutgers Univerisity in the April 30, 2009 edition of the Plant and Pest Advisory newsletter, Landscape, Nursery, and Turf Edition from Rutgers University. Go to http://njaes.rutgers.edu/pubs/plantandpestadvisory/2009/ln043009.pdf for the full article.
Thursday, February 5, 2009
Landscape - New Publication on Tree and Shrub Troubleshooting
The following is information on a new NRAES publication on troubleshooting problems on woody broadleaf trees and shrubs.
Broadleaved Shrubs and Shade Trees
Problems, Picture Clues, and Management Options
Why didn’t my azaleas flower this year? … Why is my maple tree showing its fall colors in July? … What’s been chewing little round holes in the leaves of my roses? … What’s causing those unsightly brown spots on the flowers of my prized dogwood? The answers to these questions and more can be found in NRAES-183, Broadleaved Shrubs and Shade Trees: Problems, Picture Clues, and Management Options, a guide soon to be published by NRAES. The guide was written by Mary Kay Malinoski and David L. Clement, seasoned experts who have 20 years experience fielding such questions at the University of Maryland’s Home and Garden Information Center. The guide will be an invaluable resource for home and master gardeners, students, extension and college educators, landscape professionals, and horticultural consultants. It will also be a useful addition to garden-center bookshelves and landscape-oriented mail-order catalogs.
Brimming with over 400 photos, the guide clearly illustrates over 125 problems that affect broadleaved shrubs and shade trees. Because it is focused around picture clues, it will be useful to those who have little or no prior knowledge of landscape issues. Users simply observe the problem in the landscape and then follow the guide’s easy-to-use, photo-based problem key to zero in on the cause. Management strategies are suggested for most problems.
Features
Click on order form for a larger version to print.
Broadleaved Shrubs and Shade Trees
Problems, Picture Clues, and Management Options
Why didn’t my azaleas flower this year? … Why is my maple tree showing its fall colors in July? … What’s been chewing little round holes in the leaves of my roses? … What’s causing those unsightly brown spots on the flowers of my prized dogwood? The answers to these questions and more can be found in NRAES-183, Broadleaved Shrubs and Shade Trees: Problems, Picture Clues, and Management Options, a guide soon to be published by NRAES. The guide was written by Mary Kay Malinoski and David L. Clement, seasoned experts who have 20 years experience fielding such questions at the University of Maryland’s Home and Garden Information Center. The guide will be an invaluable resource for home and master gardeners, students, extension and college educators, landscape professionals, and horticultural consultants. It will also be a useful addition to garden-center bookshelves and landscape-oriented mail-order catalogs.
Brimming with over 400 photos, the guide clearly illustrates over 125 problems that affect broadleaved shrubs and shade trees. Because it is focused around picture clues, it will be useful to those who have little or no prior knowledge of landscape issues. Users simply observe the problem in the landscape and then follow the guide’s easy-to-use, photo-based problem key to zero in on the cause. Management strategies are suggested for most problems.
Features
- Descriptions of 30 abiotic problems, 30+ diseases, 55+ insect pests, 7 wildlife pests, and 4 miscellaneous organisms (like algae, moss, and mushrooms)
- 430+ color photos
- 200+ pages
- Introductory chapter on diagnostics and nonchemical management strategies
- Photo-based key to symptoms and possible causes
- Compact, spiral-bound design with laminated cover
- Glossary
Click on order form for a larger version to print.
Saturday, November 22, 2008
Nursery and Landscape - Poor Branch Angles Will Lead to Problems Down the Road
Poor branch angles will lead to loss of branches in the future with storms or with heavy snow load. Branches with narrow angles often have ingrown bark at the branch attachment and this results a weak point. This has be a common problem in Bradford Pear. The following is an article on the subject.
Genetic makeup contributes to branch architecture and the angle of attachment in plant species. Branch angle is a predictor of wood strength and a plant’s ability to withstand compromising environmental conditions. Even though the loss of branches may be due to wind or ice load, the genetic predisposition for weak branch or wood strength is the inherent basis for the problem. Common knowledge tells us that vigorous upright branches with narrow attachment angles are prone to storm damage. Horizontal branch angles offer potentially greater wood strength. To ensure the stability and longevity of species with narrow branch angles or multistemmed upright crowns, corrective pruning should be performed on a semiregular schedule. Consider cabling or bracing on plants too old for corrective pruning.
Storm damage to Bradford Pear due to weak branch attachments (narrow branch angles). Photo by Gordon Johnson, UD.
A more intensive approach is to spread branches when plants are very young to achieve a wider branch angle. This is commonly done with fruit trees. Clothes pins on pieces of wood with small nails on both ends can be used and placed to hold the branch away from the main trunk at a wider angle.
Most information from a section of "Abiotic Plant Disorders - Symptoms, Signs and Solutions A Diagnostic Guide to Problem Solving" by Robert E. Schutzki and Bert Cregg, Departments of Horticulture and Forestry, Michigan State University Michigan State University. Go to http://www.ipm.msu.edu/cat08land/pdf/9-19abiotic.pdf for the full factsheet with photos.
Genetic makeup contributes to branch architecture and the angle of attachment in plant species. Branch angle is a predictor of wood strength and a plant’s ability to withstand compromising environmental conditions. Even though the loss of branches may be due to wind or ice load, the genetic predisposition for weak branch or wood strength is the inherent basis for the problem. Common knowledge tells us that vigorous upright branches with narrow attachment angles are prone to storm damage. Horizontal branch angles offer potentially greater wood strength. To ensure the stability and longevity of species with narrow branch angles or multistemmed upright crowns, corrective pruning should be performed on a semiregular schedule. Consider cabling or bracing on plants too old for corrective pruning.
Storm damage to Bradford Pear due to weak branch attachments (narrow branch angles). Photo by Gordon Johnson, UD.A more intensive approach is to spread branches when plants are very young to achieve a wider branch angle. This is commonly done with fruit trees. Clothes pins on pieces of wood with small nails on both ends can be used and placed to hold the branch away from the main trunk at a wider angle.
Most information from a section of "Abiotic Plant Disorders - Symptoms, Signs and Solutions A Diagnostic Guide to Problem Solving" by Robert E. Schutzki and Bert Cregg, Departments of Horticulture and Forestry, Michigan State University Michigan State University. Go to http://www.ipm.msu.edu/cat08land/pdf/9-19abiotic.pdf for the full factsheet with photos.
Thursday, August 28, 2008
Landscape - Late Summer Premature Leaf Fall
Late summer premature leaf fall is a common occurance in some trees and shrubs. The following is more information.
Tuliptrees (Liriodendron tulipifera) are exhibiting yellow leaves at this time – far earlier than the typical fall defoliation. This phenomenon occurs in a number of species, but tuliptree and river birch are two plants in which late summer leaf drop is common.
Leaf drop in tulip tree. Photo courtesy of Janna Beckerman, Purdue University.
The leaf drop is a response to low soil moisture levels near the end of the growing season. When soil moisture levels are low, there is not enough water to support all of the leaves on the tree. Rather than create a situation where all the leaves are supplied with a limited amount of water, trees and shrubs will often “self-prune” or “self-thin” their canopies so the remaining leaves are supplied with adequate water. This keeps the tree in overall better health than it would be if it tried to retain all of its leaves.
Early yellowing or other coloration could be a result of environmental stress or pest or disease, so it is important to check your plants thoroughly. However, trees that partially defoliate are not necessarily in trouble.
Adapted from "Late Summer Leaf Fall in Trees" by Mike Mickelbart, Dept. of Horticulture & Landscape Architecture and Janna Beckerman, Dept. of Botany & Plant Pathology, Purdue University, Purdue Plant and Pest Diagnostic Laboratory.
Tuliptrees (Liriodendron tulipifera) are exhibiting yellow leaves at this time – far earlier than the typical fall defoliation. This phenomenon occurs in a number of species, but tuliptree and river birch are two plants in which late summer leaf drop is common.
Leaf drop in tulip tree. Photo courtesy of Janna Beckerman, Purdue University.The leaf drop is a response to low soil moisture levels near the end of the growing season. When soil moisture levels are low, there is not enough water to support all of the leaves on the tree. Rather than create a situation where all the leaves are supplied with a limited amount of water, trees and shrubs will often “self-prune” or “self-thin” their canopies so the remaining leaves are supplied with adequate water. This keeps the tree in overall better health than it would be if it tried to retain all of its leaves.
Early yellowing or other coloration could be a result of environmental stress or pest or disease, so it is important to check your plants thoroughly. However, trees that partially defoliate are not necessarily in trouble.
Adapted from "Late Summer Leaf Fall in Trees" by Mike Mickelbart, Dept. of Horticulture & Landscape Architecture and Janna Beckerman, Dept. of Botany & Plant Pathology, Purdue University, Purdue Plant and Pest Diagnostic Laboratory.
Wednesday, August 27, 2008
Landscape - Watering Trees and Shrubs
With the current drought in mid-state it is critical to water trees and shrubs to prevent premature defoliation
While many homeowners are diligent to keep their lawns watered and green, trees and shrubs often get ignored. Reducing stress to trees and shrubs this time of year is critical. As we go into the fall, trees are shifting internal resources and undergoing physiological changes that will enable them to withstand the rigors of the winter to come. If plants are subjected to severe stresses now, they will be more predisposed to various winter injuries. With this in mind, irrigating trees and shrubs is important in landscapes.
Give good, long soakings rather than frequent light waterings. A typical rule of thumb is to provide at least one inch of irrigation per week. How many gallons of water this translates into depends on the size of the tree. If we measure the width of crown spread of a tree we can calculate the area under the drip line. We can then figure the volume of water needed to cover this area with one inch of water.
Increase the irrigation amount as temperature soar. The one inch per week is a good rough guide but peak evaporative demand can approach three inches per week in Delaware during extremely hot summer weather.
Apply mulch properly. Mulching is the best way to conserve precious soil moisture in the landscape.
Use irrigation bags on newly established trees. Gator bags are designed to provide about 15 gallons of water over several hours, providing an easy way to ensure a slow steady watering. Gallons of water needed to provide 1 inch of irrigation under the dripline of trees of various sizes
Don’t allow water to run-off. Water that runs off is wasted water. If you’re watering by hand and notice water running off, move from tree to tree to allow water to soak in before resuming watering.
Wilting leaves, leaf scorch, dropping leaves and drooping leaders in conifers are signs of water stress. If using overhead sprinklers, some experts argue against watering late in the evening due to possible disease problems associated with wet foliage. Morning is the best time to water.
Adapted from the Michigan State University Landscape Alert Newsletter.
While many homeowners are diligent to keep their lawns watered and green, trees and shrubs often get ignored. Reducing stress to trees and shrubs this time of year is critical. As we go into the fall, trees are shifting internal resources and undergoing physiological changes that will enable them to withstand the rigors of the winter to come. If plants are subjected to severe stresses now, they will be more predisposed to various winter injuries. With this in mind, irrigating trees and shrubs is important in landscapes.
Give good, long soakings rather than frequent light waterings. A typical rule of thumb is to provide at least one inch of irrigation per week. How many gallons of water this translates into depends on the size of the tree. If we measure the width of crown spread of a tree we can calculate the area under the drip line. We can then figure the volume of water needed to cover this area with one inch of water.
Increase the irrigation amount as temperature soar. The one inch per week is a good rough guide but peak evaporative demand can approach three inches per week in Delaware during extremely hot summer weather.
Apply mulch properly. Mulching is the best way to conserve precious soil moisture in the landscape.
Use irrigation bags on newly established trees. Gator bags are designed to provide about 15 gallons of water over several hours, providing an easy way to ensure a slow steady watering. Gallons of water needed to provide 1 inch of irrigation under the dripline of trees of various sizes
Don’t allow water to run-off. Water that runs off is wasted water. If you’re watering by hand and notice water running off, move from tree to tree to allow water to soak in before resuming watering.
Wilting leaves, leaf scorch, dropping leaves and drooping leaders in conifers are signs of water stress. If using overhead sprinklers, some experts argue against watering late in the evening due to possible disease problems associated with wet foliage. Morning is the best time to water.
Adapted from the Michigan State University Landscape Alert Newsletter.
Monday, August 25, 2008
Drought Stressed Trees and Shrubs
We are seeing signs of drought effects on trees and shrubs across mid-state now. The following are some thoughts on the current situation.
- Premature leaf drop is occurring in drought stressed trees and shrubs due to the drought condition. With the drought in 2007 and now stress in 2008, expect long lasting effects. Trees and shrubs that have been severely stressed for two years in a row will have much reduced food reserves due to lowered photosynthesis. Winter survival may be affected and you may see more trees and shrubs that do not leaf out properly in the spring.
- Drought also reduces the amount of defensive chemicals that stressed trees and shrubs can produce making them more prone to damage from insects and diseases. Late season borer damage would be an example.
- We have very limited subsoil moisture reserves in many areas. This will be a concern as we go into the fall. Root death may occur and this can lead to increase in root rots over the winter when rains do occur.
- It is critical to water stressed trees and shrubs before leaf drop occurs. Water deeply - shallow watering will not help plants recover sufficiently. Limited rainfall (less than 0.5 inch) also will not be enough and additional water will be needed.
Gordon Johnson, Extension Horticulture Agent, UD, Kent County
Tuesday, August 12, 2008
Landscape - Grade Changes Can Affect Trees
The following is a short article on how soil grade changes can affect trees.
Adding or removing even a small amount of soil at the surface of the tree’s root zone will damage the tree. Excess soil on top of the roots reduces the oxygen available. Since most of a tree’s roots are in the top 6 inches, removal of soil also means removal of roots. Avoid grade changes greater than 2 inches. Be aware that the root system may spread far beyond the furthest branches (drip line) of the tree, typically two to three times or more.
Information from Dr. Susan Barton, Extension Ornamental Horticulture Specialist, UD.
Adding or removing even a small amount of soil at the surface of the tree’s root zone will damage the tree. Excess soil on top of the roots reduces the oxygen available. Since most of a tree’s roots are in the top 6 inches, removal of soil also means removal of roots. Avoid grade changes greater than 2 inches. Be aware that the root system may spread far beyond the furthest branches (drip line) of the tree, typically two to three times or more.
Information from Dr. Susan Barton, Extension Ornamental Horticulture Specialist, UD.
Wednesday, July 16, 2008
Landscape - Decaying Trees are Hazards
Decay in living trees can weaken their structure and create a situation where injury to people or damage to property could result from falling limbs, trunk breakage, or tree toppling. The following is information on this subject from the University of Kentucky.
A tree normally would not present a hazard in the landscape unless there is a potential target for it to fall on. After all, a falling tree in the middle of a forest is not the hazard that a similar tree would be in a school playground. County Extension Agents, arborists, landscapers, and grounds maintenance personnel should recognize how tree decay disease can create a real hazard in the landscape.
Trees that represent a hazard can often be recognized by evidence or indicators of decay disease or tree structural weaknesses. Some of these will be listed here. An actual evaluation of hazard trees is best done by a professional certified arborist. Knowing that some of these indicators are present should give the tree owner reason to contact a certified arborist.
Visible external evidence. The following is a partial list of tree hazard indicators which, if present, are cause for concern and a stimulus to look more closely at the problem to determine if a hazard really exists.
Tree branch and foliage appearance (indicating a root or lower trunk problem): diminished size, frequency, and health of buds; decreased annual twig growth; reduced canopies; unsatisfactory size, density, and color of foliage; epicormic growth; deadwood and dieback in the crown.
Tree structure: poor crown balance; multiple branch attachments; narrow crotch angles between trunks or between branches and trunk, especially with included bark; long slender non-tapering branches; abnormal crooks in branches; and leaning trees.
Tree diseases and defects: canker diseases; trunk and branch cracks, splits, and bulges; dead bark; bark texture changes; weeping wounds; cavities and hollows; topped trees; branch stubs; flush cuts; dead wood and broken, hanging branches; root decay; deep stem fluting; lack of basal flare; and girdling roots.
Biological indicators: fruiting bodies of decay fungi on buttress roots, trunk, or limbs; fungal mycelial mats or fans; fungal rhizomorphs; insect emergence holes; insect frass; bird or mammal nesting holes; and bee colonies inside the tree.
Site factors: nearby building construction; trenching through the root zone; changes in water drainage patterns; soil compaction; clearing of a densely wooded site leaving remaining trees exposed to wind; soil erosion; changes in grade such as cuts and fills; extremely light soils providing poor root anchorage.
Buried evidence. Less accessible, but very important to tree hazard determination is the partially buried area at the base of the trunk which includes the buttress or flare roots. The root flare area may need to be carefully excavated to reveal decay, fungal mycelium and rhizomorphs, dead bark, injuries, cracks, and other tree defects. For a tree to be safe and healthy, it is necessary for most of the lower trunk and buttress roots to be free from injury and disease.
Evidence inside the tree. Decay of the wood inside the tree can often be foretold by visual evidence such as fungal fruiting bodies, hollows, and cracks. Nevertheless, to survive, grow, and have healthy foliage, trees need only intact bark and a few outer rings of the wood, so a badly decayed tree might not always appear to be a hazard. Therefore, it is important to determine just how much decay is present to determine if the disease has progressed to the point of making the tree hazardous. The presence of decay and a cavity is not necessarily an indication that tree removal is necessary provided that the healthy shell of the trunk surrounding the decayed center is sufficiently thick.
Arborists have tools that can be used to determine what is inside the tree or inside the buttress roots so that a more accurate picture of the tree strength can be obtained. Some of these tools include:
A mallet, used skillfully can help detect a cavity, but it does not tell how much decay is present.
The sound impulse hammer (e.g., Metriguard hammer) or ultrasonic instruments such as the Silvatest and Arborsonic detectors use sound velocity patterns to reveal tree defects.
An increment borer facilitates sampling for study of the annual growth rate of the tree (dendrochronology) and for determining the extent of internal wood decay.
A portable electric drill with a long narrow twist drill bit can be used to determine interior decay and hollow conditions by noting changes in sawdust color, texture, and odor and changes in resistance to penetration at various depths.
A more precise variation of the drill method is provided by the Resistograph F500 decay detection device. A thin, about 1/16 inch diameter probe rotating at high speed is inserted into the tree and penetrates up to a depth of almost 20 inches at constant speed. The changes in power demands on the electric motor resulting from passing through sound wood and decayed wood are printed out on a recording device at the same scale as the distance traversed.
Other detectors employing the concept of wood penetration such as the Densitomat-400, the Decay Detecting Drill (DDD 200), and the Resistograph 1410 operate on the same principle as the Resistograph F500 and also provide a graphic record of the results of drilling.
Electrical resistance measurements inside the tree will show a difference between decayed and healthy wood. The Shigometer is used to detect internal discoloration and decay in the tree and also to provide a relative measure of its vitality.
New non-invasive technology such as thermograpy (measuring a tree's radiant heat), ultrasonic tomography (using sound sensors outside the tree with computer analysis of data), echography (radar), and computed tomography (like the CAT scan used in medicine) are being tried experimentally to detect decay in trees.
As tree decay detection technology advances, it may be possible someday to accurately map out the extent of decay inside the tree. If future technology brings computer-aided 3-dimensional models and species-specific tree strength formulas, it should make hazard tree evaluation even more precise.
Reprinted from "DECAYING TREES CAN BECOME HAZARDS" By John Hartman in the August 6, 2007 edition of the Kentucky Pest News from the Universty of Kentucky, College of Agriculture.
A tree normally would not present a hazard in the landscape unless there is a potential target for it to fall on. After all, a falling tree in the middle of a forest is not the hazard that a similar tree would be in a school playground. County Extension Agents, arborists, landscapers, and grounds maintenance personnel should recognize how tree decay disease can create a real hazard in the landscape.
Trees that represent a hazard can often be recognized by evidence or indicators of decay disease or tree structural weaknesses. Some of these will be listed here. An actual evaluation of hazard trees is best done by a professional certified arborist. Knowing that some of these indicators are present should give the tree owner reason to contact a certified arborist.
Visible external evidence. The following is a partial list of tree hazard indicators which, if present, are cause for concern and a stimulus to look more closely at the problem to determine if a hazard really exists.
Tree branch and foliage appearance (indicating a root or lower trunk problem): diminished size, frequency, and health of buds; decreased annual twig growth; reduced canopies; unsatisfactory size, density, and color of foliage; epicormic growth; deadwood and dieback in the crown.
Tree structure: poor crown balance; multiple branch attachments; narrow crotch angles between trunks or between branches and trunk, especially with included bark; long slender non-tapering branches; abnormal crooks in branches; and leaning trees.
Tree diseases and defects: canker diseases; trunk and branch cracks, splits, and bulges; dead bark; bark texture changes; weeping wounds; cavities and hollows; topped trees; branch stubs; flush cuts; dead wood and broken, hanging branches; root decay; deep stem fluting; lack of basal flare; and girdling roots.
Biological indicators: fruiting bodies of decay fungi on buttress roots, trunk, or limbs; fungal mycelial mats or fans; fungal rhizomorphs; insect emergence holes; insect frass; bird or mammal nesting holes; and bee colonies inside the tree.
Site factors: nearby building construction; trenching through the root zone; changes in water drainage patterns; soil compaction; clearing of a densely wooded site leaving remaining trees exposed to wind; soil erosion; changes in grade such as cuts and fills; extremely light soils providing poor root anchorage.
Buried evidence. Less accessible, but very important to tree hazard determination is the partially buried area at the base of the trunk which includes the buttress or flare roots. The root flare area may need to be carefully excavated to reveal decay, fungal mycelium and rhizomorphs, dead bark, injuries, cracks, and other tree defects. For a tree to be safe and healthy, it is necessary for most of the lower trunk and buttress roots to be free from injury and disease.
Evidence inside the tree. Decay of the wood inside the tree can often be foretold by visual evidence such as fungal fruiting bodies, hollows, and cracks. Nevertheless, to survive, grow, and have healthy foliage, trees need only intact bark and a few outer rings of the wood, so a badly decayed tree might not always appear to be a hazard. Therefore, it is important to determine just how much decay is present to determine if the disease has progressed to the point of making the tree hazardous. The presence of decay and a cavity is not necessarily an indication that tree removal is necessary provided that the healthy shell of the trunk surrounding the decayed center is sufficiently thick.
Arborists have tools that can be used to determine what is inside the tree or inside the buttress roots so that a more accurate picture of the tree strength can be obtained. Some of these tools include:
A mallet, used skillfully can help detect a cavity, but it does not tell how much decay is present.
The sound impulse hammer (e.g., Metriguard hammer) or ultrasonic instruments such as the Silvatest and Arborsonic detectors use sound velocity patterns to reveal tree defects.
An increment borer facilitates sampling for study of the annual growth rate of the tree (dendrochronology) and for determining the extent of internal wood decay.
A portable electric drill with a long narrow twist drill bit can be used to determine interior decay and hollow conditions by noting changes in sawdust color, texture, and odor and changes in resistance to penetration at various depths.
A more precise variation of the drill method is provided by the Resistograph F500 decay detection device. A thin, about 1/16 inch diameter probe rotating at high speed is inserted into the tree and penetrates up to a depth of almost 20 inches at constant speed. The changes in power demands on the electric motor resulting from passing through sound wood and decayed wood are printed out on a recording device at the same scale as the distance traversed.
Other detectors employing the concept of wood penetration such as the Densitomat-400, the Decay Detecting Drill (DDD 200), and the Resistograph 1410 operate on the same principle as the Resistograph F500 and also provide a graphic record of the results of drilling.
Electrical resistance measurements inside the tree will show a difference between decayed and healthy wood. The Shigometer is used to detect internal discoloration and decay in the tree and also to provide a relative measure of its vitality.
New non-invasive technology such as thermograpy (measuring a tree's radiant heat), ultrasonic tomography (using sound sensors outside the tree with computer analysis of data), echography (radar), and computed tomography (like the CAT scan used in medicine) are being tried experimentally to detect decay in trees.
As tree decay detection technology advances, it may be possible someday to accurately map out the extent of decay inside the tree. If future technology brings computer-aided 3-dimensional models and species-specific tree strength formulas, it should make hazard tree evaluation even more precise.
Reprinted from "DECAYING TREES CAN BECOME HAZARDS" By John Hartman in the August 6, 2007 edition of the Kentucky Pest News from the Universty of Kentucky, College of Agriculture.
Monday, June 2, 2008
Landscape - Tree Care Following Storm Damage
Recent storms brings the topic of trees and wind damage to mind. The following is an article on tree care following storm damage.
Trees suffering severe injury as a result of storms aren't always the luck of the draw. Certain tree species are much more susceptible to damage than others. For instance, silver maples, Bradford pears, willows, green ash, and hackberry can suffer considerable damage. Red maples and oaks sustain only light damage. Other factors that play a part in storm damage include age and maintenance history of the tree. Large old trees, improperly pruned trees, and those trees with narrow crotch angles can be particularly susceptible to damage. Severe injury can reduce the life of a tree. Wounds caused by storm injury can provide an entrance point for decay organisms and insects. Wounds can also disfigure the tree or ruin its intended function.
If a tree has been damaged, carefully examine the extent of damage. Give immediate attention to trees that are hazards to people or property. If a power line is involved, utility company personnel are the only ones who should be working in the area. After the elimination of hazardous situations, individual tree care can be assessed. Unfortunately, assessment is a judgement call with a large gray area. Severe splitting of the main trunk or an injury that removes more than 1/3 of the bark around the tree is a wound that few trees can survive. Broken tree tops are also severe injuries. Injured trees take time to heal. Repair methods are geared toward assisting the tree in healing as quickly as possible. Most repair work involves pruning. Use correct pruning techniques to minimize the size of the wound and avoid flush cuts. Remove large, uneven stubs by pruning back to an undamaged side branch. Wound dressings are not recommended. Cabling and bracing may be appropriate if the cost involved can be justified. This method of repair does not save trees with extensive structural damage.
After deciding the treatment necessary, the next decision is who will do the work. Tree care specialists should be used for complicated jobs. For minor damage on small trees a landscaper with knowledge of proper pruning procedures, access to proper equipment, and desire can handle the job. Severe damage is better left to someone who specializes in this area. When contracting repair work out, both the homeowner and the tree service professional must clearly understand the work to be done and the cost involved. If your area has received considerable damage, repair professionals may be heavily booked. It may take some time before they can get to your site. It's important to keep people away from potentially dangerous situations until the necessary work is completed.
If tree replacement ends up being your only alternative, select tree species and cultivars with a sturdy reputation. Red maple is a good selection. Oak species include pin, white, swamp white, bur, and red. Linden (both American and littleleaf), thornless honeylocust, and ginkgo are other possibilities. Contact the county extension office for more recommendations.
Adapted from Tree Care Following Storm Damage by Sherry Rindels, Department of Horticulture, Iowa State University.
Trees suffering severe injury as a result of storms aren't always the luck of the draw. Certain tree species are much more susceptible to damage than others. For instance, silver maples, Bradford pears, willows, green ash, and hackberry can suffer considerable damage. Red maples and oaks sustain only light damage. Other factors that play a part in storm damage include age and maintenance history of the tree. Large old trees, improperly pruned trees, and those trees with narrow crotch angles can be particularly susceptible to damage. Severe injury can reduce the life of a tree. Wounds caused by storm injury can provide an entrance point for decay organisms and insects. Wounds can also disfigure the tree or ruin its intended function.
If a tree has been damaged, carefully examine the extent of damage. Give immediate attention to trees that are hazards to people or property. If a power line is involved, utility company personnel are the only ones who should be working in the area. After the elimination of hazardous situations, individual tree care can be assessed. Unfortunately, assessment is a judgement call with a large gray area. Severe splitting of the main trunk or an injury that removes more than 1/3 of the bark around the tree is a wound that few trees can survive. Broken tree tops are also severe injuries. Injured trees take time to heal. Repair methods are geared toward assisting the tree in healing as quickly as possible. Most repair work involves pruning. Use correct pruning techniques to minimize the size of the wound and avoid flush cuts. Remove large, uneven stubs by pruning back to an undamaged side branch. Wound dressings are not recommended. Cabling and bracing may be appropriate if the cost involved can be justified. This method of repair does not save trees with extensive structural damage.
After deciding the treatment necessary, the next decision is who will do the work. Tree care specialists should be used for complicated jobs. For minor damage on small trees a landscaper with knowledge of proper pruning procedures, access to proper equipment, and desire can handle the job. Severe damage is better left to someone who specializes in this area. When contracting repair work out, both the homeowner and the tree service professional must clearly understand the work to be done and the cost involved. If your area has received considerable damage, repair professionals may be heavily booked. It may take some time before they can get to your site. It's important to keep people away from potentially dangerous situations until the necessary work is completed.
If tree replacement ends up being your only alternative, select tree species and cultivars with a sturdy reputation. Red maple is a good selection. Oak species include pin, white, swamp white, bur, and red. Linden (both American and littleleaf), thornless honeylocust, and ginkgo are other possibilities. Contact the county extension office for more recommendations.
Adapted from Tree Care Following Storm Damage by Sherry Rindels, Department of Horticulture, Iowa State University.
Landscape - Preventing Storm Damage to Trees
After recent storms the topic of storm damage and trees comes to mind. The following are some things you can do to reduce storm damage to trees.
There is no way, except for complete enclosure, to protect trees from all storm damage. Trees are not adapted to worst-case storms -- only to our average wind climate. Listed are several things to minimize the main types of storm damage:
Let trees adjust to the wind environment. Tight staking and guying from the time of planting holds a tree in place while preventing internal adjustment to wind loading. Always stake and tie the tree loosely where the stem can move and bend in the wind. Keep ties in place for a few growing seasons to ensure a well-established root system. Continue to loosen and, eventually, release the ties. Leave the support stakes in place to protect the stem from mechanical damage. After five to seven years, remove all tree support. The tree will continue to grow and adjust to its new environment.
Practice proper pruning techniques by cutting branches before they become larger than 1 inch in diameter. Do not damage the branch collar (Figure 1). The branch collar is part of the stem and, if damaged by poor pruning, provides an avenue of attack into the main stem for pests. Proper pruning minimizes a number of structural problems that occur in association with new wood growth around a pruned branch.
Eliminate co-dominant branches. Prune forked branches and branches that arise opposite each other on the stem early. Cut one side off now to prevent loving the whole tree later if it splits in a storm. In trees with opposite branching patterns (such as ash or maple), proper branch training is essential for a long-lived, storm resistant tree.
Keep trees as healthy as possible with timely watering and proper fertilization. Healthy, vigorous trees adjust more quickly to changes in the environment, are more wind firm and react more effectively to damage.
Do not over-fertilize the tree with nitrogen or over-water the soil. This can increase the crown surface area and/or decrease the rooting area. This type of biological change makes the tree susceptible to storm damage.
Eliminate lopsided crowns. Prune branches to produce a reasonably symmetrical crown. If more than 70 percent of the crown is on one side of a mature tree, consider tree removal and replacement. Guying and bracing branches are last-ditch efforts when a tree has to be saved in spite of itself.
Remove or treat pest problems such as branch cankers to minimize potential damage. Do not over-treat tree hollows. Do not remove decayed wood from hollows unless it falls away in your hands. Cleaning hollows can lead to further internal damage. Cover the openings to hollows to allow the tree to grow over the opening; covering also prevent animals from expanding the hollow and keeps water from running in.
Keep the tree growing upright with one main stem. Prune away branches that compete in height with the main stem. Eliminate branches with tight or narrow crotches.
Install lightning protection systems on historic, rare, specimen or recreational area trees. Consult a qualified arborist or urban forester to ensure adequate design. Lightning protection systems are covered in detail in the section "Lightning Protection Systems."
Continue to promote wind firmness by not over-crowding trees and by proper guying and bracing. A tree must always be able to move in the wind. Do not keep a tree tied into position with tight cables. In a stand of trees, slowly remove trees over a number of years to allow wind firmness to develop in the remain-ing trees.
Information from "Storm Damaged Trees: Prevention and Treatment" by Kim Coder, Professor Silvics/Ecology, Warnell School of Forest Resources, University of Georgia. Go to http://pubs.caes.uga.edu/caespubs/pubcd/C806.htm for the full fact sheet.
There is no way, except for complete enclosure, to protect trees from all storm damage. Trees are not adapted to worst-case storms -- only to our average wind climate. Listed are several things to minimize the main types of storm damage:
Let trees adjust to the wind environment. Tight staking and guying from the time of planting holds a tree in place while preventing internal adjustment to wind loading. Always stake and tie the tree loosely where the stem can move and bend in the wind. Keep ties in place for a few growing seasons to ensure a well-established root system. Continue to loosen and, eventually, release the ties. Leave the support stakes in place to protect the stem from mechanical damage. After five to seven years, remove all tree support. The tree will continue to grow and adjust to its new environment.
Practice proper pruning techniques by cutting branches before they become larger than 1 inch in diameter. Do not damage the branch collar (Figure 1). The branch collar is part of the stem and, if damaged by poor pruning, provides an avenue of attack into the main stem for pests. Proper pruning minimizes a number of structural problems that occur in association with new wood growth around a pruned branch.
Eliminate co-dominant branches. Prune forked branches and branches that arise opposite each other on the stem early. Cut one side off now to prevent loving the whole tree later if it splits in a storm. In trees with opposite branching patterns (such as ash or maple), proper branch training is essential for a long-lived, storm resistant tree.
Keep trees as healthy as possible with timely watering and proper fertilization. Healthy, vigorous trees adjust more quickly to changes in the environment, are more wind firm and react more effectively to damage.
Do not over-fertilize the tree with nitrogen or over-water the soil. This can increase the crown surface area and/or decrease the rooting area. This type of biological change makes the tree susceptible to storm damage.
Eliminate lopsided crowns. Prune branches to produce a reasonably symmetrical crown. If more than 70 percent of the crown is on one side of a mature tree, consider tree removal and replacement. Guying and bracing branches are last-ditch efforts when a tree has to be saved in spite of itself.
Remove or treat pest problems such as branch cankers to minimize potential damage. Do not over-treat tree hollows. Do not remove decayed wood from hollows unless it falls away in your hands. Cleaning hollows can lead to further internal damage. Cover the openings to hollows to allow the tree to grow over the opening; covering also prevent animals from expanding the hollow and keeps water from running in.
Keep the tree growing upright with one main stem. Prune away branches that compete in height with the main stem. Eliminate branches with tight or narrow crotches.
Install lightning protection systems on historic, rare, specimen or recreational area trees. Consult a qualified arborist or urban forester to ensure adequate design. Lightning protection systems are covered in detail in the section "Lightning Protection Systems."
Continue to promote wind firmness by not over-crowding trees and by proper guying and bracing. A tree must always be able to move in the wind. Do not keep a tree tied into position with tight cables. In a stand of trees, slowly remove trees over a number of years to allow wind firmness to develop in the remain-ing trees.
Information from "Storm Damaged Trees: Prevention and Treatment" by Kim Coder, Professor Silvics/Ecology, Warnell School of Forest Resources, University of Georgia. Go to http://pubs.caes.uga.edu/caespubs/pubcd/C806.htm for the full fact sheet.
Sunday, June 1, 2008
Landscape - Saving Trees in Construction Areas
We often are called to look at trees in decline in areas where construction occured. The following is some information on this problem and how to avoid tree loss from North Carolina State University.
Understanding the problem
Tree roots develop and survive where there is adequate oxygen and moisture. Most active tree roots are in the top 3 feet of soil; the majority are in the top 12 inches. The more compacted or poorly drained the soil the closer the roots are to the soil surface. Roots normally grow outward to about three times the branch spread. Only 50 percent of the trees root system occurs between the trunk and the dripline. Roots on one side of the tree normally supply the foliage on the same side of the tree. When the roots on one side of the tree are injured the branches on that side of the tree may die back or die. With some trees, such as maple, the effect may develop anywhere in the tree canopy.
You should decide which trees add value to the property and take necessary measures to protect them. Consider the location, species, size, age, and overall health. Will the tree provide needed shade in the summer? Is there too much shade to grow the plants you hope to install? Does the tree hide an undesirable view? Will roots pose a problem to sidewalks or driveway? Is it a high maintenance tree that will require frequent spraying for insect or disease control? Does it drop messy fruit pods or seeds? How adaptable is it to environmental changes?
Older trees do not adapt as well to changes in the environment as young trees. Some young trees may be replaced at a lower cost than trying to preserve them, especially if extensive treatment will be required to help them recover from construction damage. The length of annual twig growth and the size and color of leaves are indications of health and vigor. Examine the tree for dead wood and indication of decline.
Pre-construction care
Ideal, a tree protective plan is developed before construction begins. Many roots are destroyed when construction equipment pass over the root zone. Simply placing a barrier around the trunk of the tree does not protect most of the tree's root system. Place tall, conspicuous stakes and fencing at the ends of the branches on the sides where trucks or bulldozers will be operating. Groups of trees usually stand a better chance of survival than individual specimens.
Minimize construction traffic to a few paths which are covered with 6 to 10 inches of mulch and do not allow parking under desirable trees. Avoid storing construction material under trees. Do not store or spread soil beneath the canopy of trees which are to be saved. Be sure that grading changes do not cause water to be channeled towards the trees.
From Erv Evans, Consumer Horticulturist, NC State University. Go to http://www.ces.ncsu.edu/depts/hort/consumer/factsheets/trees-new/text/tree_damage.html for the full set of fact sheets
Understanding the problem
Tree roots develop and survive where there is adequate oxygen and moisture. Most active tree roots are in the top 3 feet of soil; the majority are in the top 12 inches. The more compacted or poorly drained the soil the closer the roots are to the soil surface. Roots normally grow outward to about three times the branch spread. Only 50 percent of the trees root system occurs between the trunk and the dripline. Roots on one side of the tree normally supply the foliage on the same side of the tree. When the roots on one side of the tree are injured the branches on that side of the tree may die back or die. With some trees, such as maple, the effect may develop anywhere in the tree canopy.
You should decide which trees add value to the property and take necessary measures to protect them. Consider the location, species, size, age, and overall health. Will the tree provide needed shade in the summer? Is there too much shade to grow the plants you hope to install? Does the tree hide an undesirable view? Will roots pose a problem to sidewalks or driveway? Is it a high maintenance tree that will require frequent spraying for insect or disease control? Does it drop messy fruit pods or seeds? How adaptable is it to environmental changes?
Older trees do not adapt as well to changes in the environment as young trees. Some young trees may be replaced at a lower cost than trying to preserve them, especially if extensive treatment will be required to help them recover from construction damage. The length of annual twig growth and the size and color of leaves are indications of health and vigor. Examine the tree for dead wood and indication of decline.
Pre-construction care
Ideal, a tree protective plan is developed before construction begins. Many roots are destroyed when construction equipment pass over the root zone. Simply placing a barrier around the trunk of the tree does not protect most of the tree's root system. Place tall, conspicuous stakes and fencing at the ends of the branches on the sides where trucks or bulldozers will be operating. Groups of trees usually stand a better chance of survival than individual specimens.
Minimize construction traffic to a few paths which are covered with 6 to 10 inches of mulch and do not allow parking under desirable trees. Avoid storing construction material under trees. Do not store or spread soil beneath the canopy of trees which are to be saved. Be sure that grading changes do not cause water to be channeled towards the trees.
From Erv Evans, Consumer Horticulturist, NC State University. Go to http://www.ces.ncsu.edu/depts/hort/consumer/factsheets/trees-new/text/tree_damage.html for the full set of fact sheets
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