Sunday, November 30, 2008

Nursery and Landscape - South Jersey Conference

The following is information on the South Jersey Landscape Conference and Nursery Growers Meeting being held this coming Wednesday.

The 2008 South Jersey Landscape Conference and Nursery Growers Meeting will be held on Wednesday, December 3, 2008 from 8:00 A.M. to 4:30 P.M. at Masso’s Crystal Manor, South Delsea Drive in Glassboro, NJ. A general session in the morning will be for all growers and landscape professionals. The afternoon session will be spilt into two concurrent sessions. All commercial producers and marketers of trees, shrubs, and perennials are invited to the growers meeting. The landscape conference will be for all landscapers and ground maintenance professionals. Professional certification credits and NJ pesticide applicator units will be given at the conclusion of each session.

The general session for both groups will feature a keynote address on the “Outlook for the Future of the Nursery and Landscape Industry” by Corey Connors, Director of Legislative Relations of the American Nursery and Landscape Association (ANLA) in Washington, D.C. Dr. Chris Obropta, Specialist in Water Resources, for Rutgers NJAES, Cooperative Extension will address “Impervious Cover and Its Impact on Water Runoff and Management”. “This topic is increasingly important to all landscape and nursery professionals” said Carl Nordstrom, moderator and director of the New Jersey Nursery and Landscape Association. Ms. Pat Hastings, Pesticide Education Coordinator with Rutgers NJAES, Cooperative Extension, will review pesticide safety issues. Two NJDEP Pesticide Applicator Core units will be given to all New Jersey Pesticide Applicators attending this talk. Mr. Mike Korpit of the US Department of Labor OSHA will discuss some new and review some old safety regulations for nurserymen and landscapers.

The Nursery Growers sessions will focus on Weed Management by Dr. Steve Hart, Specialist in Ornamental Weed Science with Rutgers NJAES Cooperative Extension, and New Ornamental Native Plants by Bruce Crawford, Director of the famous Rutgers Gardens in New Brunswick. Mr. Marc Teffeau, Director of Research and Regulatory Affairs at the ANLA in Washington will discuss New Research Initiatives to help the Industry. Dr. Zinati, Specialist in Nursery Management at Rutgers NJAES Cooperative Extension will share her research results on using mycorrhizae for nursery plants with growers.

The Landscape Conference, chaired by Jerome Frecon, Agricultural Agent with Rutgers NJAES, Cooperative Extension in Gloucester County, will feature presentations on Proper Tree Planting and Management, Leaf Scald and its Impact on Tree Decline, and Developing an Organic Landscape Management Business. Said Mr. Frecon, “We will close the conference with our popular panel of landscapers sharing ideas that have made their business successful”. Certified Nursery and Landscape Professionals will also receive 7 credits for participating in the entire conference.

Regular information will be posted on the web site at including a detailed copy of the program. Pre-registration is required. Contact Jerry Frecon at (856) 307-6450 Ext. 1 for more information. Call Carl Nordstrom at (800) 314-4836 to register for the conference and meeting.

Business - Being an Entrepreneur II

Now more than ever it is important for green industry businesses to think and act like entrepreneurs. Entrepreneurship is recoginizing business opportunities and acting on those opportnities to create successful enterprises. The following is the second in a series on being an entrepreneur from a presentation I have given.

Gordon Johnson, Extension Horticulture Agent, UD, Kent County

Saturday, November 29, 2008

Landscape and Nursery - Know Your Plant Diseases: Rusts

the following are pictures of three rust diseases found on woody plants in landscapes and nurseries. The first four pictures are of ash rust, the next two of cedar-apple rust, the last four pictures are of cedar-quince rust.

Ash rust

Ash rust

Ash rust

Ash rust

Cedar Apple Rust

Cedar-Quince Rust

Cedar-Quince Rust

Photos by Bob Mulrooney, extension plant pathologist, UD.

Business - Being an Entrepreneur I

Now more than ever it is important for green industry businesses to think and act like entrepreneurs. Entrepreneurship is recoginizing business opportunities and acting on those opportnities to create successful enterprises. The following is the first in a series on being an entrepreneur from a presentation I have given.

Gordon Johnson, Extension Horticulture Agent, UD, Kent County

Friday, November 28, 2008

Landscape - Strategies to Reduce Winter Damage

I recently had a conversation with a colleague on reducing winter damage in boxwoods. This brought to mind the whole subject of reducing winter damage. Dr. Ann Gould and Dr. Gladis Zinati had a good article on the subject in a recent Rutgers newsletter and I have reprinted their recommendations with some of my own comments in italics.

Strategies to minimize wind exposure, winter injury, and sunscald include:

• Install physical barriers such as canvas, burlap, or wood slats on the exposed sides to reduce winter desiccation (the screens should be placed two feet away from the tree or shrub and anchored securely). Plant wraps can be used for cold sensitive plants that are important in the landscape.

• Select the appropriate plants (e.g. pine, spruce or juniper) as windbreaks in areas of high exposure to wind (northwest side).

• Apply sufficient moisture in the root zone before the soil freezes in the fall, and mulch the ground to retain moisture in the winter. (avoid excessive watering however)

• Avoid late summer and early fall fertilization (this simulates and encourages plant growth late in the season which may not harden off properly for the winter).

• Select ornamental plants that exhibit medium to high tolerance to low temperatures (use references that give cold hardiness information)

• Protect conifers and broadleaf evergreens from drying by spraying antidessicants in late fall and throughout the winter months when temperatures are above 45 F. You must have good coverage and apply when temperatures are not to low.

• Prevent winter sunscald in newly planted, thin barked trees (such as maple, tuliptree, ash and crabapple) by wrapping the trunk with burlap or other tree wrapping materials (the wrap can be kept in place up to two years).

• Prune dead twigs and branches that serve as sites for secondary pests.

• Fertilize with complete fertilizer, if soil test results showed nutrient deficiency, by spreading the fertilizer on the ground in early spring. Potassium is important in overwintering.

Information reprinted from "Winter Injury in theNew Jersey Landscape" by Ann B. Gould, Ph.D., Specialist in Plant Pathology and Gladis Zinati, Ph.D., Specialist in Nursery Management in the November 6, 2008 edition of the Plant and Pest Advisory, Landscape, Nursery, and Turf Edition from Rutgers University.

Nursery and Greenhouse - Challenges and Opportunities V

This is a continuation of the series on challenges and opportunities for greenhouse and nursery businesses during the current economic downturn and in the near future.

  • Opportunities will continue to expand for native, locally grown plants. Opportunities exist for the selection and promotion of superior native plant cultivars. Team up with propagators that are working with native plants and promote superior selections.
  • Look to opportunities with sustainable urban landscape movements and other sustainable landscape movements. Remember, you are in the green industry and as such you are part of the environmental movement. Understand where green initiatives are occurring and where they will be expanding.
  • Use resource efficient practices - water, fertilization, energy, labor, and other inputs need to be used as efficiently as possible.
  • Work hand in hand with landscape architects and their plant choices. Educate each other on the plants available and what plants to grow and use in the future.
  • Look at plant lists for those projects that are forward thinking and use this as a guide for what to grow.
  • Consider pot in pot production in nurseries to reduce blow over and give better root conditions. Container plants give more flexibility in planting programs but more management and marketing skill is needed with container production.
  • Take advantage of networking opportunities – learn who is making decisions on what plants are being used in projects and develop one on one relationships with them

Gordon Johnson, Extension Horticulture Agent, UD, Kent County

Thursday, November 27, 2008

Happy Thanksgiving

For Thanksgiving, I thought I would repost a picture I took of some wild turkeys crossing the road on the way into work one day last summer. Good looking gobbler with some hens. Happy Thanksgiving to all who read my blog!

A Thanksgiving Thank You

"The man who has planted a garden feels that he has done something for the good of the world." Vita Sackville-West

I write this thanksgiving "thank you" to all of you in the horticulture industry that grow and take care of the plants that so enrich our lives.

Gordon Johnson, Extension Horticulture Agent, UD, Kent County

Wednesday, November 26, 2008

Nursery and Greenhouse - Challenges and Opportunities IV

This is a continuation of the series on challenges and opportunities for greenhouse and nursery businesses during the current economic downturn and in the near future.

  • Customers desire choice, quality, and a reasonable price. Focus your business on these areas.
  • Energy conservation will continue to be critical as energy prices will rise again in the future. Natural gas more is more stable but expect increases from current levels. Look into green energy sources as government incentives are enhanced.
  • Consider how communication has changed with the expansion of the internet. Social networks are a good example. Take advantage of these new ways to interact with customers in your marketing. Targeted advertising and marketing efforts will be needed. Understand how to use the new media (much of it is free) to your advantage.
  • One continuing challenge is water. Irrigation in containers not well understood and you need to stay abreast of the latest technologies to manage water efficiently.
  • Population issues will continue in this region. This is both an opportunity and a challenge. The challenge is cost of land. The opportunity is an increased customer base with lower transportation cost to reach those customers due to proximity to markets. Expect local advantages to increase in the future. Take advantage of buy local movements and support those movements.
  • Mechanization opportunities exist but still are not cost effective, especially for smaller operations. Where possible, replace labor with mechanization.
  • Immigration reform is critical for the industry to have sufficient labor. Stay politically involved and support nursery and greenhouse groups working for immigration reform.

Gordon Johnson, Extension Horticulture Agent, UD, Kent County

Greenhouse and Nursery - Heat from Compost

In the composting process, heat is generated and piles can go well over 150 F. If a portion of the heat can be captured from this process, you could use it to heat greenhouses and nursery production houses. One organic grower in Delaware did this on a very small scale. The following is more information and my thoughts on the subject.
  • Kathy Brooks, an organic herb grower in Kent County, partially heated her small greenhouse using heat from a compost pile. She is offereing information on how she did this. Here is the information from Kathy: Due to the overwhelming response to the most recent article on my heating system in Farm Show magazine I created a shortened version of the book that I am writing so I could get it to those wanting information immediately. I am pleased to announce that it is now available. The black and white version sells for $10.00 and the color copy is $15.00 plus $2.00 shipping cost. I included construction details, pictures and information on avoiding problems. To order please send your check payable to: Kathy Brooks,7371 Canterbury Road, Felton, DE 19943. For those in the immediate area I will try to deliver them or meet at a convenient location to get them to you.
  • In Europe, market gardeners have for hundreds of years used the heat generated from decomposing straw and manure over beds to heat during cold months and grow food crops out of season. This "hot box" approach still can be used.
  • A greenhouse or nursery might consider the addition of a compost business and capture some of the heat during composting to heat production facilities. This would require some infrastructure with piping under or inside of compost piles, pumps, and heat distribution systems. It would also require adequate sizing of compost piles and having sufficient piles coming on at different times to have a constant source of heat. The materials used in the composting process is also an issue to generate enough heat.
  • One of the real potentials with this source of heat is to use it in bottom heating systems for greenhouses and nurseries where water is recirculated through the compost pile and back into the production facility.

Photos of the heating system using compost that Kathy Brooks used to heat her small greenhouse. Photos by Kathy Brooks, Misty Morning Herbs & More, Felton, DE. This same concept could be used on a larger scale for production greenhouses or nursery propagation facilities.

Gordon Johnson, Extension Agriculture Agent, UD, Kent County

Tuesday, November 25, 2008

Nursery and Greenhouse - Challenges and Opportunities III

This is a continuation of the series on challenges and opportunities for greenhouse and nursery businesses during the current economic downturn and in the near future.
  • Creative production is a key. Look for voids in the marketplace and trends that will drive markets in the future
  • Customer profiling will become even more important. The more you know about your customers, the better you will be able to plan production and market to those customers.
  • Know your cost structure. Pricing needs to based on production costs plus overhead and then adding desired profit. If costs are not know, pricing becomes a guessing game.
  • Look to the sustainable landscapes movement for opportunities – Urban stormwater mitigation, green roofs, tree planting campaigns, projects using native plants, and much more. Team up with foundations and other organizations promoting plants for the benefit of the environment.
  • Take note of suburban to urban shifts – institutional and governmental policies are influencing spending on plants in urban settings. Take time to understand these policies and the potentials they offer your business.

Gordon Johnson, Extension Horticulture Agent, UD, Kent County

Monday, November 24, 2008

Delaware Agriculture Week Program Details are Now Posted on The Web

Delaware Agriculture Week runs from January 5-10 this year and is the largest educational venue for agriculture in Delaware. It is organized by Delaware Cooperative Extension of the University of Delaware and Delaware State University with cooperation from the Delaware Department of Agriculture and many agricultural commodity groups. Detailed schedules of program offerings are now posted on the web. Following is more information.

About Delaware Ag Week

Delaware Agriculture Week consolidates farm-based educational meetings while recognizing and celebrating the industry's importance. The University of Delaware Cooperative Extension, Delaware State University Cooperative Extension and Delaware Department of Agriculture are cooperating with many partners to organize the week of agriculture related events.

An agenda of the programs planned during Ag Week 2009 is available through the Meeting Schedules link. Detailed program information for each session is now available. Information for exhibitors and sponsors is available through the Exhibitors & Sponsor Info link.

For general information regarding Delaware Ag Week contact Emmalea Ernest at (302) 856-7303 or

Keep checking this site for updates on Delaware Ag Week.

Delaware Ag Week Planning Committee:
University of Delaware Cooperative Extension
Delaware State University Cooperative Extension
Delaware Department of Agriculture
Delaware Soybean Board
Vegetable Growers Association of Delaware
Maryland/Delaware Forage Council
Delaware Equine Council
Delaware Standardbred Breeders Fund
Delaware Nursery and Landscape Association
Delmarva Forestry Seminar Planning Committee
Delaware Organic Food and Farming Association

The link for Delaware Agriculture Week is

Nursery and Greenhouse - Challenges and Opportunities II

This is a continuation of the post on challenges and opportunities for the greenhouse and nursery industry with the current economic conditions and looking into the future.
  • Nurseries and greenhouses need to re-focus on their core business. Identify your core customers and work closely to retain them.
  • This is definitely the time for a full business analysis. Find out your profit centers and areas where money is being lost. Re-think practices where you are not profiting.
  • There is a re-alignment of markets from West coast to East coast because of transportation cost. Local production of materials such as liners may be advantageous and economically viable again. Look to possible local or regional advantages.
  • If your business is in good economic shape, now may be the time to expand in the nursery business and have materials available for 3 years down the road when we come out of recession. However, be careful in your planning and consider where the market may be.
  • Regulatory and environmental initiatives such as green roofs may open up opportunities for production. Look back into urban settings for these opportunities.

Gordon Johnson, Extension Agriculture Agent, UD, Kent County

Saturday, November 22, 2008

Greenhouse - Ethylene Injury From Malfunctioning Heaters

Each year we get problems in production greenhouses due to malfunctioning heaters. The following is an article on ethylene injury that can occur with problem heaters.

Crops grown in greenhouses that utilize gas-fired unit heaters can be susceptible to ethylene injury. Ethylene (C2H4) is an odorless, colorless gas that acts as a plant hormone. Plants are very susceptible to ethylene injury at levels from 0.01 to 1 ppm or more. No other air pollutant causes a greater range of symptoms than ethylene gas. Symptoms range from misshapen leaves and flowers, thickened stems, stunted growth, flower and/or leaf abortion to epinasty. Example pictures of ethylene damage can be found at this web sites:

The effects on greenhouse crops will vary with the plant species and growth stage, temperature, length of exposure, and the concentration of the ethylene. I have noted plant injury symptoms more often in plastic greenhouses compared to glass greenhouses, due to the airtight nature of poly-greenhouses. A good bulletin on the subject was written by faculty at North Carolina State University and is titled Ethylene: Sources, Symptom, and Prevention for Greenhouse Crops. It can be downloaded free at:

An indicator plant to use for ethylene is a tomato plant. They are highly sensitive and will twist or wilt when exposed to ethylene. Tomatoes will exhibit injury within 24 hours if ethylene is present.

To avoid ethylene injury, unit heaters need proper ventilation and intake of fresh air from the outside. One square inch of vent cross section (of outside air) for every 2,500 Btu’s of heater output is recommended. Consider using a laundry dryer vent hose as a fresh air intake. Thus, if you have a 125,000 Btu heater, you would need an 8-inch diameter fresh air inlet pipe that would give you the 50 square inches you need.

Also, unit heaters need to be maintained so that the heater itself is running properly, and the distribution tube, vent stack, ventilation louvers, and fuel line are all functioning correctly.

Reprinted from "Malfunctioning unit heaters can lead to greenhouse crop problems -- check your furnaces!" by Thomas Dudek, District Extension Horticulture Agent, in the January 28, 2005 edition of the Greenhouse Alert Newsletter from Michigan State University Extension.

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 for the full factsheet with photos.

Friday, November 21, 2008

Landscape - Girdling Roods

We often see girdling roots in woody plants and this can lead to plant decline. The following is an article on the subject.

Encircling roots due to production methods, poor soil conditions, excessive mulch and narrow planting sites have contributed in one form or another to the problem of girdling. A distinction is sometimes made between two forms of girdling roots. "Girdling roots" refers to the condition that occurs when roots encircle upon themselves. Stem-girdling roots encircle the tree stem above the trunk/root collar. Both of these conditions affect the structural stability and anchoring of the plant and restrict the roots system's ability to adequately mine the soils. Stem-girdling roots compress the conductive tissue in the trunk, restricting translocation and eventually leading to trunk decay. Each situation causes a slow but progressive decline in plant performance. Treatment for girdling and stem-girdling roots consists of the selective removal of root sections. The extent of the removal varies with the condition and the length of time that the plant has been in place. Root removal may span several seasons to minimize stress to the plant. To eliminate or reduce the incidence of this problem, use proper planting procedure and long-term mulching practices. At planting, encircling roots should be cut or removed to ensure proper movement of new and existing roots into the surrounding soils. Excessive mulch layers around the bases of plants cause new roots to work their way upward to capitalize on optimal aeration, moisture and nutrient levels. Roots remain in the mulch layers and encircle as continued mulching maintains the preferred environment. Mulch layers should be removed periodically and problem roots cut and redirected.

Girdling roots (excavated and painted white) on declining Linden tree. Photo by Linda Haugen, USDA Forest Service,

Girdling roots on maple. Photo by Linda Haugen, USDA Forest Service,

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 for the full factsheet with photos.

Thursday, November 20, 2008

Nursery and Greenhouse - Challenges and Opportunities I

This is the first in a series on challenges and opportunities for nursery and greenhouse businesses. The information is from a presentation at a conference I recently attended.
  • Nursery and greenhouse businesses will need to focus on productivity, resource efficiency, and market visibility to remain profitable in the future.
  • Challenges are labor costs and availability, increased energy costs in production, increased transportation costs, and increased input costs such as containers and fertilizer.
  • The key in this economic downturn is to try to maintain cash flow. Working with your accountant and banker to analyze your cash flow situation and restructure debt if necessary is critical.
  • For the short term the credit crunch may limit your businesses ability to borrow money. If you have cash on hand, this is the time to use it
  • Inventory control will be critical. Common plants in the trade have been overproduced and are not moving well in this economic downturn. Do a lot of research before chosing plants to produce in the future. Consider producing those plants in demand but in shorter supply.

Gordon Johnson, Extension Horticulture Agent, UD, Kent County

Landscape - Problems Associated with Poor Planting Procedure

Many of our failing plants in the landscape are due to poor planting procedure. The following is an article on the subject.

The planting process involves the preplanting examination and evaluation of the plant stock type (bare-root, container, balled and burlapped [B&B], mechanical tree spade), the actual physical process of planting and the follow-up maintenance. Problems related to the planting process can originate within each of these.

Consider the idiosyncrasies with each of the previously mentioned stock types, for example, the depth of the trunk/root collar on B&B trees, encircling roots in container- grown plants, root desiccation on bare-root plants and glazing in mechanical tree spade plantings. Each one of these factors can contribute to the success or failure of the plants.

Improper handling and planting procedure contribute significantly to abiotic consequences, especially when they’re combined with soil or environmental limitations at the planting site. Symptoms related to poor planting procedures are similar to those of drought and flooding: shoot dieback, reduced leaf size, minimal shoot growth, root injury and poor root regeneration. If plant excavation is possible, examine the root system for white root tips and signs of root regeneration. Under drought or water deficits, white root tips will be absent, and existing roots will be dried and shriveled. Under excessive moisture and poor drainage, the root system will also lack white root tips and exhibit signs of anaerobic conditions. The blackened outer surface of the roots will slough off, exposing inner gray and water-soaked, stained tissue.

In addition to the obvious plant symptoms, evidence of twine around the base of the trunk, scars from staking or other signs of mechanical injury may lead to conclusions on the causal factors and required treatment. Problems caused by poor planting procedures can be due to marginal plant stock quality; poor soil ball or container media moisture prior to planting or during establishment; improper planting depth, either too high or too low; compacted planting sites and poor drainage through the soil profile; improper irrigation scheduling following planting; and improper mulching practices.

This tree was planted too deeply. The palnting depth is marked by the darkened area. Trees planted too deeply may be drought stressed and often have poor root development. Photo by Joseph LaForest, University of Georgia,

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 for the full factsheet with photos.

Wednesday, November 19, 2008

Landscape - Galls and Burls on Woody Plants

Galls and Burls sometimes grow on woody plants. The following is an article on these abnormal growths.

Galls and burls are abnormal growths on woody plants. They can occur on branches, trunks and, in some cases, on roots of woody plants. Galls may be caused by an insect or disease; however, the origin or causal factors for burls and other callus outgrowths are unknown. Abnormal growths form through a proliferation of cells. These cells continue to develop and do not differentiate into normal tissue types. In some cases, the outgrowth results from a cluster of shoots. Each year, new shoots are initiated and increase the layers of the mass.

Burl on elm. Photo by USDA Forest Service - Ogden Archive, USDA Forest Service,

Cottonwood tree with a very large crown gall (Agrobacterium tumefaciens) high on the trunk. Photo by William Jacobi, Colorado State University,

Oak galls, photo by James Solomon, USDA Forest Service,

Gall caused by a wasp. Pennsylvania Department of Conservation and Natural Resources - Forestry Archive,

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 for the full factsheet with photos.

Tuesday, November 18, 2008

Landscape and Nursery - Snow and Ice Damage

With the potential for the first snowfall soon at hand, the topic of ice and snow damage to woody plants is very timely. The following is a short article on the subject.

Ice and snow accumulation on branches can cause internal splits or cracks, bark tearing and/or breakage. Plant architecture, branching structure and wood strength can be predictors of damage from excessive snow or ice load. Unfortunately, hidden cavities in the wood or flaws in branch attachment can increase the damage potential. Plants with multiple stems can be tied to provide support. This may be especially helpful on upright narrow-leaved evergreens. Excessive amounts of snow can be carefully removed to alleviate the stress on lateral branches. Ice should be allowed to melt naturally. Branches become extremely brittle when laden with ice. Mechanically removing the ice may increase the amount of injury. Once the ice has melted, the branches will usually return to their normal positions.

Ice damage to tree. Photo by Joseph O'Brien, USDA Forest Service,

Heavy snow load can break branches. Photo by Joseph O'Brien, USDA Forest Service,

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 for the full factsheet with photos.

Greenhouse - Plant Temperatures vs Air Temperatures

If the temperature of your greenhouse plant is lower than the air temperature, it will develop more slowly. The following is a good article on plant temperatures versus air temperatures.

Temperature controls plant development (leaf numbers, time to flower) and height (DIF). The temperature of the plant is determined by air temperature, light intensity, humidity, air movement, media temperature and water status. In the past growers were comfortable measuring just air temperature since it’s easy to monitor and is “close enough” to the real temperature of the plant. However, high fuel bills have made “close enough” not very comfortable anymore.

Measuring plant temperature isn’t easy. The growing point (meristem) is where the plant senses temperature so that’s where we need to measure. But growing points are small and often buried under leaves so they’re hard to reach reliably. During research it’s OK to carefully put small thermocouples into the growing points, but that wouldn’t work in production ranges. For under $100 (more likely less than $60) you can buy a small infrared thermometer that will quickly and accurately measure growing point temperatures. The units are about the size of a small (not a universal) remote control and have a red laser pointer that shows where the thermometer is reading. The closer to the surface the more accurate the reading. It takes no time at all to uncover the meristem, target the laser pointer and get a reading. Infrared thermometers are available from greenhouse suppliers or can be found on the Internet.

It’s fun to shine laser beams around and measure infrared temperatures, but does it really mean anything? Ever have an early New Guinea Impatiens crop that just didn’t grow? They looked healthy, had good roots but just sat in the pot for weeks. Dr. Royal Heins found the temperature of New Guinea growing points could be up to 15 degrees colder than air temperature. The cold growing point was caused by large amounts of water evaporating from the surrounding leaves due to low relative humidity in the house. The solution: increase the relative humidity. The effect: the plants started to grow. How much could you increase your profits if your early New Guinea’s started to grow immediately after planting? A lot more than you invested in the infrared thermometer.

Reprinted from "Air temperature doesn’t always equal plant temperature" by Dean Krauskopf, MSU Greenhouse Agent in the February 17, 2006 edition of the Greenhouse Alert newsletter from Michigan State University.

Monday, November 17, 2008

Turf - Brown Grass Areas

Brown grass areas this time of year in cool season turf are commonly because of undesirable species and weeds that have gone dormant or have been killed by frost. The following are common problem weeds in lawns that brown out this time of year.
  • Bermudagrass, also called wiregrass, will be going winter dormant this time of year leaving straw colored areas in lawns. Zoysiagrass and other warm season perennial grasses will also go winter dormant.
  • Nimblewill is a common perennial grass weed that will go winter dormant this time of year.
  • Annual grass weeds such as crabgrass and goosegrass are killed by frosts and straw colored areas will be seen where they were heavy.

Dormant burmudagrass is turning straw colored in turf areas now.

Gordon Johnson, Extension Horticulture Agent, UD, Kent County

landscape and Turf - Frost Heaving

Frost heaving occurs in winters with significant freeze and thaw cycles. The following is an article on the subject.

Frost heaving results from the alternate freezing and thawing of soils. Heaving exposes the roots to cold and desiccation and is especially a problem on newly planted or shallow-rooted plants. Fall planted ground covers, perennials and small container shrubs are highly vulnerable (as is late planted turf grass). Ground cover plugs and small container plants should be fully planted in soil. This may sound obvious, but with a tendency to plant high, these plants are often found planted in the mulch rather than completely surrounded by soil. In addition, a uniform mulch layer aids in preventing rapid soil temperature fluctuations. In larger container plants, planting high in the mulch layer may expose the upper level of the root system enough to influence plant quality the following spring. Proper planting technique is the best defense against frost heaving. In turf, timely planting so that the grass puts on good fall growth and the use of straw over grass seedings will reduce frost heaving.

Perennials that frequently frost heave:
Pincushion Flower (Scabiosa)
Coral Bells (Heuchera)
Shasta Daisy (Leucanthemum)
Blanket Flower (Gaillardia)
Pigsqueak (Bergenia)
Coreopsis (Coreopsis)
Seathrift (Armeria)
Whirling Butterflies (Gaura)
Foamflower (Tiarella)
Foamy Bells (Heucherella)
Garden Mum (Chrysanthemum)
Painted Daisy (Tanacetum)

Frost heaving in Heuchera exposing roots to dessication.

Some 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 for the full factsheet with photos. Other information and photo from an article by Cindy Haynes, Extension Horticulturist, Iowa State University.

Sunday, November 16, 2008

Greenhouse, Landscape, Turf, and Nursery - Understanding Systemic and Translaminar Insecticides

Often, we choose an insect control chemical without really knowing how it works or how it is best used. The following is an article on systemic and translaminar insecticides and where they work best.

While many insecticides kill pests by contact activity, some insecticides have either systemic or translaminar properties. Systemic insecticides are pesticides in which the active ingredient is primarily taken up by plant roots and transported throughout the plant, such as the growing points where it can affect plant-feeding pests. Many of our neonicitinoid insecticides such as imidacloprid fall in this catagory when used as a soil drench. Systemics move within the vascular tissues, either through the xylem (water-conducting tissue) or phloem (food-conducting tissue) depending on the characteristics of the material. The water solubility of systemic insecticides determines their movement within plants. Very water soluble materials are readily taken up by plant roots or leaves. Systemic insecticides are most effective on insects with piercing- sucking mouthparts, such as aphids, whiteflies, mealybugs and soft scales because these insects feed within the vascular system. Most of the systemic insecticides have minimal activity on spider mites because spider mites remove chlorophyll and don't feed within the vascular tissues. Systemic insecticides should be applied when plants have an extensive, well-established root system and when they are actively growing.

Translaminar insecticides penetrate leaf tissues and form a reservoir of active ingredient within the leaf. This provides residual activity against certain foliar-feeding insects and mites. Because the active ingredient can move through leaves, thorough spray coverage is less critical to control spider mites, which normally feed on leaf undersides. Insecticides/miticides with translaminar properties include but not limited to abamectin (Avid), pyriproxyfen (Distance), chlorfenapyr (Pylon) and spinosad (Conserve). In general, these types of materials are active against spider mites and/or leafminers.

Adapted from an article by Tina Smith in the December, 2006 section of the New England Greenhouse Update Newsletter.

Turf - Top Complaints From Your Turf Grass if It Could Talk 16-20

This is a continuation of the series on top complaints you would hear from your turf if it could talk (from a presentation I recently gave).

Saturday, November 15, 2008

Greenhouse - Whiteflies in Poinsettias

Whiteflies can be late season problem in poinsettias in some greenhouses. The following is an article on the subject from the University of Maryland.

Late Season Whitefly Control

Most greenhouses are reporting very low whitefly activity this fall but there are a few exceptions. Some people let the weeds grow under the benches which served as epicenters for whitefly populations. If you treated with imidacloprid (Marathon) or dinotefuran (Safari) as soil drenches after pinching then you should have pretty good control of whitefly on the foliage that expanded after the application. John Speaker is noting that if whiteflies are present in a greenhouse the adults are having the most success establishing populations on the lower foliage where the systemic did not move into the foliage that was already expanded before a systemic insecticide was applied to the substrate.

Many of the poinsettia varieties are showing bract color so foliar insecticide applications get tricky at this point. Most of the pesticides will state on the label “do not apply when bracts are in color”. In past years we have observed that Abamectin (Avid), pyridaben (Sanmite), chlorfenapyr (Pylon), acetamiprid (TriStar) and dinotefuran (Safari) applied as foliar sprays in bract stage without causing any noticeable damage on poinsettia varieties such as ‘Freedom’, ‘Prestige’ and ‘Monet’. If you try late season whitefly control try out a spray on a few plants before treating the whole crop.

Article and picture from the November 7, 2008 edition of the Greenhouse TPM/IPM Weekly Report from the University of Maryland Cooperative Extension, Central Maryland Research and Education Center