Thursday, April 30, 2009

Landscape - Some Scales Being Found Currently in the Landscape

The following is a picture of some scales currently being found in Delaware landscapes.

Minute cypress scale and Maskell scale side by side. Photo by Nancy Gregory, Plant Diagnostician, Department of Plant & Soil Sciences, University of Delaware

Landscape - Seiridium Canker

The following is information on Seiridium canker, a disease that is being found more and more on Leyland Cypress.

Seiridium canker has been seen on leyland cypress. Stressed trees are more susceptible to this damaging fungal pathogen. Cankers are formed on main trunks, branches or twigs, and appear as sunken, dark areas. Resin flow or ooze will often be noticeable from the canker areas, but resin is not a diagnostic feature alone because it can be due to other factors. Affected branches often turn a reddish brown. Fruiting bodies may be found in the cankers with the aid of a hand lens or microscope. Spores are spread by water splash or mechanical means on pruning tools. There are no chemical controls for Seiridium canker in the landscape. Reduce drought and other stress on trees. As spores may be spread by pruning and wounding, take care in pruning out diseased areas. Prune at least one inch below cankered area and clean pruners in alcohol or 10% bleach. Remove and discard trimmings.

Photo by Tracy Wootten, Extension Horticulture Agent, UD, Sussex County.

Information from Nancy Fisher Gregory, Plant Diagnostician, Department of Plant & Soil Sciences, University of Delaware

Wednesday, April 29, 2009

Landscape - Cool Season Annual Grass Weeds in Landscape Beds.

The following is a short article on two common cool season grass weeds found in landscape beds in the spring.

Cool season annual grass weeds in landscape beds.

There are two cool season annual grass weeds that are commonly found competing in landscape beds during the spring. Annual bluegrass is easily identified this time of year by its compact growth and production of many seed heads low to the ground. When annual bluegrass infests ground covers and perennial beds it can form a dense mat that will stunt plantings. Downy brome is another common winter annual grass that is highly competitive in ground covers and perennial beds during the spring. It has a more upright growth and can be identified by its densely hairy leaves and sheaths and drooping oat-like seed heads when mature. Both these species will die out by mid-June. However, they will have reseeded leaving a seed bank for germination in late summer.

Effective control of these grass weeds can be obtained with the use of preemergence herbicides applied in late summer (such as prodiamine). Non selective herbicides such as glyphosate, glufosinate, and pelargonic acid can be used as spot treatments at any time but are most effective on young plants that are not fully tillered. If escapes are found in beds, it is important to control these species in late winter or early spring before they start to produce seed heads. Selective over-the-top postemergence grass herbicides for downy brome in landscape beds include sethoxydim, fluazifop-P-butyl, and clethodim. Only clethodim is effective on annual bluegrass. Large, well tillered plants or plants with seedheads may not be adequately controlled by these materials and may still reseed.

Gordon Johnson, Extension Horticulture Agent, UD, Kent County

Greenhouse - Thrips

In recent greenhouse visits, one pest that was found in many greenhouses was thrips. The following is a review of how to manage thrips using insecticides.

For growers using pesticides to manage thrips, plan to treat in the early evening. Thrips have two mass flights per day, so sprays in the early evening may contact more thrips. Small droplet sprays, repeated applications (two to three sprays about 5 days apart) and treating before you see a peak in adult numbers on yellow sticky cards are critical. Adult thrips numbers on cards tend to peak every two to three weeks. Apply insecticides before this peak, so adults will be killed before they lay eggs. A mass aggregretion pheromone or thrips lure is also available to be placed into sticky cards to aid in early detection of thrips.

To manage thrips, shorten spray intervals to 4-5 days and rotate pesticides with different modes of action. Some options for management (based upon grower feedback) include Avid (abamectin-group 6) tank mixed with Azatin (azadirachtin- Group 18B), Mesurol (methiocarb-group 1A), Pedestal (novaluron-group 15) tank mix with Pylon (chlorfenaphyr- group 13), Safari (dinotefuran Group 4A) and Conserve (spinosad-group 5). Overture (pyridalyl) (unknown mode of action) has contact, translaminar and some ingestion activity and can be added into your rotation program. It is labeled for thrips and caterpillars but may take from 7 to 14 days before you see control.

Horticultural oil (Pure Spray Green, Saf-T-Side, or Ultra fine oil) may also be an option provided label cautions regarding plant safety are followed. Note that Mesurol has a 24 hour REI plus it may leave an unsightly residue and Pedestal is an IGR labeled for immature stages. In addition, TriStar (acetamiprid - group 4A) or Aria (flonicamid - Group 9C) may help suppress thrips.

Information from the New England Greenhouse Update:
http://www.negreenhouseupdate.info/greenhouse_update/?p=2552

Tuesday, April 28, 2009

Landscape - Horned Oak Gall, Gouty Oak Gall

The following is information on two common gall problems on pin oaks.

Most galls pose little threat to tree health but horned oak and gouty oak gall infestations can be a significant problem on pin oaks - disfiguring them, weighing down the branches, and eventually even killing the trees. While several control approaches have been evaluated and others are in progress, there is no specific recommendation at present.

One confounding factor is the nearly 3-year life cycle of the tiny wasp that causes these galls; most of that time is spent in woody galls ranging from small and inconspicuous to mature galls the size of golf balls. It is very difficult to spray tall trees, and one would have to do this 3 years in a row, just before buds show green tips in spring in an attempt to break the life cycle. So far, there has been little success getting systemic (e.g, soil-applied or trunk injected) insecticides to translocate into the woody galls. When feasible, pruning out soft and alive (greenish-brown) galls from lightly-infested trees may be worthwhile. Dried up brown galls are already “spent” and pose no threat.

Gouty Oak Gall. Photo from Michael Masuik, Penn State University

Horned oak gall. Photograph by: USDA Forest Service, www.forestryimages.org

Reprinted from "Horned Oak Gall/Gouty Oak Gall - No Good Control Recommendation" By Dan Potter and Lee Townsend, University of Kentucky in the current edition of the Kentucky Pest News.

Landscape - Scale Insects: Obscure Scale

This is the 20th in a series on scale insects in the landscape. This post is on the Obscure Scale. Information is from the University of Maryland.

Obscure Scale (Melanaspis obscura), Family Diaspididae

Plants Damaged: Obscure scale is an armored scale found on many pin oaks in the landscape, but is also found on a few other species of oak such as white oak. It has been reported on grape, dogwood, walnut, Prunus spp, pecan and hickory.

Damage Symptoms: Yellowing of foliage and dieback. Life Cycle: The obscure scale has one generation per year in Maryland. Second instar male and females overwinter and mature in spring in May. Eggs are laid in late June and July. Crawlers are present from July through early September. Stoetzel and Davidson (1973) found that this scale on white oak was one month behind its development on red oak.

Monitoring: Adult female covers are circular and gray to black in color. The scales are usually crowded together and overlap each other on the branches and sometimes in the trunks of trees.

Control: Horticultural oil or Distance at crawler emergence. The crawlers should be active in central Maryland by the end of June.

Photo by James Solomon, USDA Forest Service, Bugwood.org

Information from "Scales Commonly Encountered in Maryland Landscapes and Nurseries" by Stanton Gill, Extension Specialist in IPM for Nurseries and Greenhouses,and Suzanne Klick and Shannon Wadkins, Technicians, Central Maryland Research and Education Center University of Maryland Cooperative Extension.

Monday, April 27, 2009

Landscape - IPM Services as a Business

Integrated Pest Management (IPM) programs can be offered as services to clients. The following are some considerations.

When initially introducing an IPM program to a potentially new client or to an existing client it needs to be determined how much they want to be educated on IPM. Obviously, not all landscape clients are the same and although some will express great interest in the IPM approach (they will probably be the most loyal clients), others will only desire that their landscapes are aesthetically pleasing and are not overly concerned how the desired results are achieved. Hence, less time should probably be devoted to attempting to educate this latter client on IPM methods. Ideally, a pre-written brochure that briefly explains the concept of IPM and gives an outline of the proposed program should be distributed to clients. The brochure can inform the client that landscape IPM programs provide monitoring services and knowledgeable decision- making abilities. The brochure can also state that IPM methods provide superior results over non-thinking traditional landscape management methods that rely exclusively on calendar cover sprays. During the initial visit, a rough site map can be prepared and later formalized if the customer purchases the IPM program. Site maps can be an excellent way to show off your knowledge to a potential client. Photocopied maps can also be a convenient method of maintaining monitoring records.

Landscape IPM programs have a reputation of being more expensive to implement than do traditional landscape management methods. IPM programs do have a tendency to be more expensive primarily because of the greater emphasis given to cultural management strategies (pruning, mulching, irrigation, site amendments, IPM appropriate design/redesign, etc.). To keep IPM programs more price competitive, the IPM related services could be charged separately. Their cost would be in addition to the standard fee established for monitoring and decision-making. The price of an IPM program is generally based on how much time will be required for each monitoring visit. Monitoring time estimates are subsequently based on the size of the property and the number of key plants and key locations present at the site (e.g., there are specific time estimates that have been calculated and can be used as guidelines). Possible spray costs, the number of monitoring visits necessary and the travel time to the site all require consideration when estimating an IPM fee. Provide written records of this information for each site.

Information from "Developing an IPM Program for your Landscape Company" by Steven K. Rettke, Ornamental IPM Program Associate, Rutgers University in the April 2, 2009 edition of the Plant and Pest Advisory, Landscape, Nursery, and Turf edition.
http://njaes.rutgers.edu/pubs/plantandpestadvisory/2009/ln040209.pdf

Landscape - Scale Insects: Holly Pit Scale

This is the 19th in a series on scale insects in the landscape. This post is on the Holly Pit Scale. Information is from the University of Maryland.

Holly Pit Scale (Aterolecanium puteanum Russell), Family Asterolecandidae

Plants Damaged: American holly, Burford holly, and Japanese holly. Most of the infestations have been found on holly growing on the Eastern shore of Maryland.

Damage Symptoms: Pitting and distortion of woody tissue on branches and trunk of the tree. Heavy infestations cause dieback of the plant.

Life Cycle: Mature females overwinter in a pit. The pit is caused by the feeding damage to the plant tissue. Crawlers emerge over a long period of time during the summer. Once nymphs have settled on a place on the plant they do not move.

Monitoring: Examine twigs and trunk of tree for pit-like depressions with a scale insect in the middle of the pit.

Control: Horticultural oil or Distance and oil applied when crawlers are present.

Photo by Mike Raupp, University of Maryland

Information from "Scales Commonly Encountered in Maryland Landscapes and Nurseries" by Stanton Gill, Extension Specialist in IPM for Nurseries and Greenhouses,and Suzanne Klick and Shannon Wadkins, Technicians, Central Maryland Research and Education Center University of Maryland Cooperative Extension.

Sunday, April 26, 2009

Landscape - Summer Pest and IPM Walks

The following is information on summer pest and IPM walks offered by University of Delaware Cooperative Extension through the Ornamentals Short Course Program.

Pest Walk ­

Date: June 9
Time: 4 p.m.—6 p.m.
Location: University of Delaware Botanic Gardens, Newark, DE
Cost: $10
Registration: Call 302-831-2506 to register.
Credits: Pesticide and CNP

Tour the grounds of the UDBG to learn about common and (sometimes unusual) disease and insect problems occurring in the landscape.

Instructors: Brian Kunkel and Bob Mulrooney

IPM Walk ­

Date: July 15
Time: 6:30 p.m.—9:30 p.m.
Location: Fischer Greenhouse & University of Delaware Botanic Gardens, Newark, DE
Cost: $10
Registration: Call 302-831-2506 to register.
Credits: Pesticide and CNP

Start in the Fischer Greenhouse with a brief discussion of “What is IPM” and then tour the grounds of the UDBG in search of both insect pests and beneficial insects in the landscape.

Instructors: Brian Kunkel and Carrie Murphy

Landscape - Scale Insects: Elongate Hemlock Scale

This is the 18th in a series on scale insects in the landscape. This post is on the Elongate Hemlock Scale. Information is from the University of Maryland.

Elongate Hemlock Scale (Fiorinia externa Ferris), Family Diaspididae

Plants Damaged: Hemlock is the predominant tree we see this scale damaging in Maryland but it also attacks spruce, pine and Taxus yew.

Damage Symptoms: This scale feeds on the needles and leaves of infested plants. Feeding causes chlorosis of foliage and needle drop and dieback of the plant.

Life cycle: There are two generations per season of hemlock elongate scale. Crawlers are active in May. The nymphs settle on the foliage of the plant where they spend their whole life cycle. The generations overlap for this scale which makes it somewhat challenging to control. Crawlers can be produced throughout the summer and into the fall.

Monitoring: Examine needles on the undersides for the presence of this scale

Control: Distance can be applied to the crawlers. Horticultural oil can be used to control overwintering females. Soil applications of dinotefuran (Safari) are effective in control of this scale.


Information from "Scales Commonly Encountered in Maryland Landscapes and Nurseries" by Stanton Gill, Extension Specialist in IPM for Nurseries and Greenhouses,and Suzanne Klick and Shannon Wadkins, Technicians, Central Maryland Research and Education Center University of Maryland Cooperative Extension.

Saturday, April 25, 2009

Landscape - Scale Insects: Gloomy Scale

This is the 17th in a series on scale insects in the landscape. This post is on the Gloomy Scale. Information is from the University of Maryland.

Gloomy Scale (Melanaspis tenebricosa (Comstock)), Family Diaspididae

Plants Damaged: This armored scale is commonly found on maples. It is also reported on several woody plants including dogwood, sweet gum, poplar, catalpa, black locust, willow, and grape.

Damage Symptoms: The heaviest damage is reported on maples with dieback of terminal growth on heavily infested trees.

Life cycle: Fertilized females overwinter. Egg laying occurs in early July and continues through August. Crawlers are present a short time after egg laying. Adult males are present in August.

Monitoring: Female covers are circular and brown to gray in color. Shed skins in the center appear to be shiny black.

Control: A mixture of 1% horticultural oil and Distance could be used on small trees. Dinotefuran (Safari) applied as a soil drench may control this pest


Information from "Scales Commonly Encountered in Maryland Landscapes and Nurseries" by Stanton Gill, Extension Specialist in IPM for Nurseries and Greenhouses,and Suzanne Klick and Shannon Wadkins, Technicians, Central Maryland Research and Education Center University of Maryland Cooperative Extension.

Greenhouse and Nursery - Monitoring Soluble Salts

The following is a good article on monitoring soluble salts in greenhouse or nursery media.

Once again another growing year is upon us and I want to remind all of you who are growing plants in containers the importance of routine monitoring for soluble salts and pH. It is the easiest way to check the fertility status for your plants and can save you $’s when you catch problems early. While electrical conductivity (EC) does not tell you exactly which nutrients are available, it can help you make decisions about your fertility and irrigation programs. Additionally, a pH test will aid in determining nutrient availability and will alert you as to whether potential problems may show up.

The PourThru procedure is easy. You simply wait about an hour after irrigation when containers are at water holding capacity. Simply find three to five containers randomly from a block or irrigation zone within the nursery and tilt them at an angle sufficient enough to have water come out the bottom of the container. Sample each container individually. Collect the released water from each container in a small cup. You need only enough water to cover the EC and pH probes for an accurate reading. If you cannot retrieve a sample, simply pour a small amount of water evenly over the top of the container. You need just enough to get that sample out the bottom of the pot. You are only trying to displace the water at the bottom of the pot so you may only need a few ounces. You could use distilled water, but it’s not necessary.

North Carolina State University recommendations from Dr. Ted Bilderback suggests EC’s around 0.5 dS/m if you are using controlled release fertilizer and around 1.0 dS/m if you are using soluble fertilizer through your irrigation. Don’t forget to check the EC’s of your irrigation water and subtract that value from your PourThu EC readings. For example, if you have an EC reading of 0.5 dS/m and your irrigation water is 0.2 dS/m, then your actual reading is 0.3 dS/m, or the EC contribution of the fertilizer. If you are lower than 0.2 dS/m, you may be over-watering or you may need to apply more fertilizer. However if your EC’s are far above the suggested value, you may need to irrigate. A sustained level of 4.0 dS/M will cause root damage. You will need to irrigate and dilute the salt build-up in your containers. An EC of 1 dS/m in the morning can easily jump to 4 dS/m in the afternoon as plants pull more water than nutrients (salts) out of the potting medium, especially during high temperature days. Remember to try and keep your leaching fractions (fraction of applied water that comes out the bottom of the pot) to less than 15% whenever possible.

Remember that the following EC units all mean the same thing: mmhos/cm (milli-mhos per centimeter) = mS/cm (milli-siemens per centimeter) = dS/m (deci-siemens per meter) = 1000 μS/cm (micro-siemens per centimeter).

PourThru’s should ideally be performed weekly or even biweekly, however that may be impractical. At the very least, test before you top dress with controlled release fertilizer (CRF). If your EC’s are in range you may not need to fertilize. Also, a good rule of thumb is to monitor during hot dry periods.

Don’t forget to keep an eye on your pH. The pH range for soilless potting media is between 5.4 and 6.3 for optimum nutrient availability. Some say that since you apply fertilizers in soluble form, pH is not very important for nutrient availability in organic potting media, but monitoring for large swings in pH is wise, regardless.

Electrical Conductivity and pH meters can be purchased through nursery supply businesses, catalogs and via internet orders where you can shop for the best prices. You can even purchase combination meters that read both EC and pH. You want an EC meter with a range of 0 to greater than 4 dS/M or 0 to 4000 μS/cm. It is extremely important to purchase pH and EC standard solutions to calibrate your meters and an electrode holding solution for the pH electrode.

Monitoring your container root zone EC and pH goes a long way for preventing nutrient related problems including deficiencies and toxicities. Even pathogen and insect infestations may be kept in check, all by keeping your roots healthy.

Article by Andrew Ristvey, Extension Nursery Specialist, University of Maryland.

Friday, April 24, 2009

Landscape - White Pine Weevil

The following is information in whige pine weevil, a common pest in Delaware landscapes.

WHITE PINE WEEVIL (Pissodes strobi).

I have almost missed the opportunity again to address white pine weevil (WPW). With one of the earliest seasonal habits of all landscape pests, control of WPW is difficult or missed entirely. WPW feeds on spruces (Colorado Blue, Norway, etc.) firs, and white pines. Damage is a very characteristic “burning out” of the branch terminals that looks like a “shepherd's crook”. Unfortunately, this damage is apparent in early summer, after the insect has completed its development for the year. Affected trees are robbed of their dominant central leaders and over time grow to be uncharacteristically bushy.

WPW overwinters as an adult in the soil near hosts. On sunny spring afternoons they'll fly/climb to the tops of trees, feed on current season terminals, and lay eggs into them. Egg hatch occurs 1-2 weeks later and larvae (grubs) tunnel into the terminals. They'll feed for a month or two, eventually forming a “chip cocoon” (pupal chamber) and emerging after 2 weeks pupation. Adults feed on host plants before going dormant until next year. Scout closely NOW for the signs of WPW. Feeding leaves small droplets of resin/pitch flow on the terminals and infestations can be detected while damage is minimal. Chip cocoons left behind after adults emerge can be detected but terminal dieback is well underway by that time.

Chemical control is directed on younger, developing trees where proper branch structure is critical. Resin/sap flow is also a good indicator for when to time adult flight sprays of pyrethroids two applications 3-4 weeks apart. Another control option is neonicotinoids drenches/sprays. If using Merit, it must be applied ASAP in the spring because it takes around a month to get up into the terminals and it may be too late already. Faster translocated neonicotinoids such as Safari may still have some use this year if the weather stays cool. For cultural control, prune out the damaged central leader and select a new one. Some growers select the Northwest leader preferentially prevailing winds will allow this branch the greatest success of forming a straight leader.

Information from Casey Sclar, IPM Coordinator, Longwood Gardens

Landscape - White Pine Weevil Pictures

The following are pictures of the white pine weevil and its damage.

Terminal demonstrating characteristic "shepherd's crook" on pine from white pine weevil. Photo by USDA Forest Service Archive, USDA Forest Service, Bugwood.org.

Close-up of two white pine weevil adults. Photo by Dave Powell, USDA Forest Service, Bugwood.org.

White pine weevil larvae. Photo by Joseph O'Brien, USDA Forest Service, Bugwood.org

Newly emerged adult white pine weevil and exit holes on a pine terminal. Photo by Steven Katovich, USDA Forest Service, Bugwood.org.

Drooping leaders which eventually die on white pine or Norway spruce are the familiar symptoms of white pine weevil attack. Photo by John A. Weidhass, Virginia Polytechnic Institute and State University, Bugwood.org.

Thursday, April 23, 2009

Turf - Red Thread Disease

The following is information on red thread disease of turfgrasses.

Laetisaria fuciformis, the causal agent of Red Thread, is now infesting susceptible perennial ryegrass and fine fescue turf. Infections are characterized by the appearance of short red threads (1/8” to 1/4” long) emerging from tan-colored leaf blades. Affected patches are typically pink in color and range from 1 to 6 inches in diameter. Kentucky bluegrass and tall fescue may also be affected in the spring. Red thread is typically found on “hungry” (low fertility) turf during cool, wet weather. Well-fertilized turf may also be attacked but to a lesser extent than nitrogen deficient turf. To obtain optimum disease control, maintain adequate fertility levels, keep turf properly irrigated, avoid excessive thatch, and apply Armada, Banner, Bayleton, Chipco 26GT*, Compass, Curalan*, Eagle, Endorse, Headway, Heritage, Insignia, Prostar, Rubigan, Tartan, Trinity or Touche* per manufacturer’s recommendations. (*Not for use on home lawns)

Red thread disease on bluegrass. Photo by Mary Ann Hansen, Virginia Polytechnic Institute and State University, Bugwood.org.

Information from Bruce B. Clarke, Ph.D., Specialist in Turfgrass Pathology, Rutgers University.

Landscape - New Technologies for Pine Wilt Nematode

The following is information 0n new technologies for protection against pine wilt nematode in susceptible pines.

Pine wilt nematode (PWN) is the cause of pinewilt of Japanese black pine, Austrian pine and Scots pine in our region. We have known for years that there has been no effective control and reducing stress has been the best recommendation for reducing the incidence of disease. This recommendation has been pretty ineffective and we continue to see more tree death following drought periods. There has been some new research into the control of PWN with trunk injections of the insecticide abamectin which is also the active ingredient in Avid. This injection with the two labeled insecticide/nematicides Pinetect or Greyhound provides protection for up to 2 years for valuable landscape trees. This treatment appears to be very effective if applied before the long horned beetles that transmit the nematodes emerge in the spring. There are two applicator technologies that have been tested for pinewilt control with success (1) systemic tree injection tubes (STIT) now referred to as Pine Infusers and (2) the Wedgle injector (Arbor Systems Inc., Omaha, NE). Pines are especially difficult to inject because of the resin produced from wounding the trees. Any system that can successfully deliver the product to the pine should work.

Information from Bob Mulrooney, Extension Plant Pathologist, UD.

Wednesday, April 22, 2009

Reminder - UBDG Annual Spring Plant Sale Coming Up

The 2009 Spring plant sale to benefit the University of Delaware Botanic Gardens is coming up this Friday and Saturday. The following is more information.

2009 Spring Plant Sale

This year’s sale will feature a wide array of plants native to the Eastern United States (in addition to a selection of non-invasive exotic perennials, shrubs and trees). Incorporating natives in your backyard plantings can help preserve the diversity of local landscapes by providing nutrition and shelter for wildlife—especially insects, the foundation of the food web. Learn more about the benefits of “going native” in this year’s plant sale catalog with the article “Why We Need Native Plants” by Dr. Doug Tallamy, author of Bringing Nature Home: How Native Plants Sustain Wildlife in Our Gardens.

The University of Delaware Botanic Gardens are located on South Campus at the College of Agriculture and Natural Resources.

Plant Sale General Admission - Friday, April 24, 4 – 7 pm
Plant Sale General Admission & AG Day - Sat., April 25, 9:30 am – 4 pm

For more information go to the catalog at the following web address:

Greenhouse and Nursery - Moving Plants Outdoors

With greenhouses full and rain delaying plant sales, many Delaware greenhouses and nursery growers are moving cold tolerant plants outdoors to free up space. While risk of frost diminishes after April 20, it is not entirely risk free. The following is an article on the subject.

Growers can free up greenhouse space, by safely moving cool tolerant plants outdoors. This space can be then be refilled with another crop. In addition to saving growing space, plants grown at cool temperatures “harden off” or acclimate allowing retailers to display plants safely outdoors.

How well plants finish outdoors depends on the genetic cold tolerance of the plants, the air movement around plants, how well plants are acclimated and how well the plants are maintained, once outdoors. Tropical and subtropical warm crops such as alternanthera, angelonia, New Guinea impatiens, lantana, vinca, celosia, cleome, coleus, cosmos, gomphrena, ipomoea, melampodium, portulaca, sunflowers, zinnias, tomatoes, peppers and squash plants are naturally sensitive to cool temperatures and are not a good choice for early spring outdoor yards.

Herbaceous perennials and cool tolerant annuals, however, can be grown outdoors, but need to be acclimated or hardened off first. Cool tolerant crops include pansy, annual phlox, alyssum, osteospermum, nemesia, calibrachoa, verbena, diascia, bidens, antirrhinum (snapdragon), mimulus, lobelia and petunias.

Plants will adapt best to cooler temperatures when they have been started at optimum growing tempertures and have a well-established root system. Once plants get to their desired size they should be exposed during the day to colder temperatures and moved back inside if frost is a risk. Monitor the weather forecast and avoid moving plants outdoors if a hard frost (colder than 28°F) is predicted at any point within at least three nights of when plants would be put outside. Avoid placing plants in low-lying areas because frost will more likely settle in these areas.

Botryis blight and lack of fertilizer are two common problems which occur with outdoor growing. To prevent Botrytis, water plants in the morning and let the foliage dry before night. Plants growing outdoors may require less water and less frequent irrigation and this means that plants are fertilized less often. Although plants are being grown cool, it is important to continue to fertilize plants and maintain proper fertility. Pay particular attention during rainy periods and monitor plants for both Botrytis and nutrient leaching.

Cool media temperatures also increase the risk of root rots caused by Pythium, Rhizoctonia and Thielaviopsis. Regularly monitor roots for disease and apply fungicides early. Fungicides will work more slowly in cool media. It may take longer to see results of an application or an application may be less effective.

Be prepared to cover plants if temperatures go below 28°F. An over-wintering thermo blanket such as polyethylene or polypropylene foam can be used for this purpose.

Adapted from the current edition of the New England Greenhouse Update. http://www.negreenhouseupdate.info/greenhouse_update/index.php

Tuesday, April 21, 2009

Landscape and Nursery - Juniper Webworm

The following is information on juniper webworm. You may be seeing signs of this insect already this spring. Information is from the University of Maryland.

Juniper Webworm, Dichomeris marginella, Family Gelechidae

This caterpillar usually damages Juniperus species, especially J. horizontalis, J. depressa, J. aurea, J. stricta, and J. squamata. The moths laid the eggs on the junipers last summer. The eggs were laid on the leaves near the base of the current season’s growth. The eggs laid in summer are white to yellow and turn red just before hatch. The larvae web together leaves into silken tubes. The larvae put out silk from their mouth to create this webbing. Since the webbing is small and the caterpillars feed in this small webbed space they often go unnoticed. Also, they tend to web the thick inner growth of the juniper making it harder to detect. In the spring when the webbed branches start to turn brown they become noticeable in the landscape. The larvae in the spring produce a lot more webbing and it is much more noticeable. The larvae themselves are buried deep inside the webbing and dead branches.

Monitoring: Look for the larvae and webbing together of juniper branches in April. Larvae will pupate in a month or so and adults will be active in May to June.

Control: In April and May the easiest control is to prune out the infested foliage. In mid to late summer you should examine junipers and look for the young larvae and webbing of the needles. In the late summer or early fall you can apply Conserve to the foliage to kill the caterpillars or the new Acelepryn from Dupont.

Juniper webworm larvae. Photo from the Connecticut Agricultural Experiment Station Archive, Connecticut Agricultural Experiment Station, Bugwood.org.

Juniper webworm. Photo from the Connecticut Agricultural Experiment Station Archive, Connecticut Agricultural Experiment Station, Bugwood.org

Information from the April 17, 2009 edition of the TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers from the University of Maryland Cooperative Extension.

Turf - Brown Turf Areas in Spring

You may still be seeing brown areas in lawns that have greened up this spring. These are places where warm season grasses were dominant last year. The following is an article on the subject.

Cool season turfgrasses have greened up across the state. However, there will often be distinct areas of turf that remain brown or straw colored. These are areas where warm season weeds died out or went dormant last fall. It is important to take note of these areas and determine what control measures will be necessary this season. Crabgrass is the most common weed that winter kills leaving large browned out areas. Goosegrass could also be the culprit, especially in compact areas. Crabgrass and goosegrass are annual species that will come back from seed. Crabgrass is germinating in turf now, goosegrass will be germinating as we go into May. If you have missed the timing for crabgrass preemergence applications, dithiopyr (Dimension) is an option now as it has both preemergence and early postemergence activity on crabgrass. However, it is not safe for areas that have been or will be seeded this spring. For new seedings, quinclorac (Drive) would be the best option as a postemergence herbicide once all the crabgrass has germinated (May). Quinclorac will not control goosegrass.

Brown areas may be patches where perennial warm season grasses grew last year. These grasses will begin to regrow again in May. Bermudagrass (or wiregrass) is the most common warm season perennial grass weed that appears brown in dormancy throughout the state. Zoysiagrass is possible but usually restricted to areas near to where it was planted. Another possibility commonly found in Delaware is nimblewill which will appear as fuzzy looking patches. Both Bermudagrass and zoysiagrass spread by underground rhizomes whereas nimblewill does not. Control of these three perennial warm season grasses is difficult. Total renovation with several applications of glyphosate herbicide is often needed. Post emergence suppression of Bermudagrass can be accomplished with multiple applications of fenoxaprop (Acclaim Extra) in tall fescue turf.

Gordon Johnson, Extension Horticulture Agent, UD, Kent County

Monday, April 20, 2009

Landscape - Scale Insects: Fern Scale

This is the 16th in a series on scale insects in the landscape. This post is on the Fern Scale. Information is from the University of Maryland.

Fern Scale (Pinnaspis aspidistrae (Signoret)), Family Diaspididae

Plants Damaged: In Maryland this scale is found mainly on liriope, Rohdea and mondo (Ophiopgon) grass and ferns but it is a general feeder and has been reported on camellia, persimmon, peony, and Prunus.

Damage Symptoms: When feeding on liriope and mondo grass the scale causes yellow spots on the foliage at the feeding sites.

Life cycle: On liriope the scale has been observed overwintering as late instar females in the crown of the plants. Crawler emergence coincides with new growth emerging form the liriope in May. A second generation has been observed with crawlers present in August and September. The second generation scale appear to establish in the base of the mondo grass and liriope plants.

Control: Cut off infested foliage in early spring and remove it from the landscape. Treat with a systemic insecticide or apply Distance and oil when the crawlers emerge in May.


Information from "Scales Commonly Encountered in Maryland Landscapes and Nurseries" by Stanton Gill, Extension Specialist in IPM for Nurseries and Greenhouses,and Suzanne Klick and Shannon Wadkins, Technicians, Central Maryland Research and Education Center University of Maryland Cooperative Extension.

Turf and Landscape - Compaction

Compaction by equipment can have long-term effects on a soil. This spring planting season has seen limited periods where the soil was in perfect condition. Landscapers and turf managers should avoid the tendency to try to get on soils that are too wet. You need to wait until they are dry enough to avoid compaction. The following is a short article on the subject.

Compaction has the effect of re-arranging the soil aggregates to form a denser, less porous soil. Severe compaction will destroy these aggregates further reducing porosity. The denser soil has fewer large pores to conduct water, so increased runoff and ponding in depressions are common symptoms of compaction. The smaller pores hold water tighter resulting in a a wetter soil that dries more slowly. Soil gas exchange is slowed and oxygen can become limiting to roots. In compacted soil, the soil strength increases impeding root growth. Roots cannot easily penetrate dense compacted areas in soils. This leads to more water stress on plants and reduced ability to take up mineral nutrients.

Compaction is most severe when heavy equipment passes over the soil when it is wet because water acts as a lubricant between soil particles. This is why wet soils are more easily compacted. The problem is also worsened as the clay content of the soil increases. This is one of the issues with new developments where soils were handled when wet.

It has been estimated that over 70 percent of the compaction effect occurs in the first pass across the soil. The heavier the equipment, the more severe the effect. Factors such as increased tire size, proper inflation pressure, and the addition of tracks, duals, or tandem axles can offset some of the effect, but in many cases with very heavy construction equipment there will be a limited reduction in compaction.

In a compacted soil, tillage can help to loosen the soil and the use of an aerator can help over time. However, tillage and aeration tools will not re-create structure or the biopores from roots and earthworm activity. These redevelop over time once the site is planted. Natural forces, such as wetting/drying, freezing/thawing, and biological activity will take many years to restore a severely compacted soil. It is interesting to note that the compaction caused by covered wagons in the 1880’s in the West could still be detected over a century later.

The best advice for managing compaction is to avoid compaction. When possible stay off wet soils, operate with lighter loads, and use tracked or high floatation vehicles when possible.

Gordon Johnson, Extension Horticulture Agent, UD, Kent County

Sunday, April 19, 2009

Landscape and Nursery - Needlecast Diseases

The following is information on two common needlecast diseases of evergreens in Delaware that are now showing up.

Two major needlecast diseases have been observed this past week. Rhabdocline needlecast infects Douglas fir especially in Christmas tree plantations and nurseries where trees are planted close together. In spring needle spots are yellowish to reddish brown. Sometimes spots coalesce to discolor the entire needle. Discolored needles are cast in spring after spore discharge. Infections of newly emerging needles persist until the following spring when infected needles drop. It is usually not a serious disease in the landscape but Christmas tree growers and nurserymen should be checking trees for symptoms. If found, prepare to spray with chlorothalonil (Bravo, Daconil) when the first buds break and again 2-3 more times at 2-3 week intervals depending on the weather.

Rhizosphaeria needlecast, like Rhadbocline, infects spruce needles in spring and infected needles turn brown in fall to early spring. The first sign of infection occurs in late fall or in spring one year after infection. At that time, the fruiting bodies (pycnidia) of the fungus emerge from the stomata or "breathing" pores of infected needles--visible with a hand lens. Fruiting bodies resemble tiny black dots in neat, even rows. The second summer after infection, symptoms appear as yellow needles, which later turn purplishbrown and drop from the tree. A few of these infected needles may persist on the tree over the winter and drop off the following spring. Because of the long delay between infection in spring and needle drop the following summer, the ends of infected branches appear green and healthy. Branches appear to lose their needles from the trunk outward. Branches that repeatedly lose needles for three or four years may die. Norway spruce is more resistant than Colorado spruce, but both are affected. If control is needed, spray with chlorothalonil when the needles are half grown and repeat 2-3 times.

Information from Bob Mulrooney, Extension Plant Pathologist, UD.

Landscape and Nursery - Needlecast Disease Pictures

The following are pictures of two needlecast diseases of evergreens being found in Delaware at this time.

Close-up view of Douglas-fir needles showing symptoms of infection with Douglas-fir needlecast fungus (Rhabdocline pseudotsugae). Photo by Mike Schomaker, Colorado State Forest Service, Bugwood.org.

Rhabdocline needlecast. Photo by John W. Schwandt, USDA Forest Service, Bugwood.org. Rhabdocline apothecia are released when flaps of leaf epidermis fold back on either side of the midrib.

Symptoms of Rhizosphaera needle cast, which can be a component of the spruce decline syndrome. Photo by Joseph O'Brien, USDA Forest Service, Bugwood.org.

Rhizosphaera needle cast close up of infected needles with pycnidia (top) and healthy needle (bottom). Photo by Michael Kangas, NDSU - North Dakota Forest Service, Bugwood.org.

Saturday, April 18, 2009

Landscape and Nursery - Plants for Delaware Landscapes Featured at the 2009 UDBG Spring Plant Sale #19

This year, the University of Delaware Botanic Garden spring benefit plant sale features those plants that add to the biodiversity of the landscape and offer food and habitat for wildlife, especially insects and the birds that eat them. Many native plants are featured. This is the 19th in a series on plants being offered at the UDBG spring plant sale that are recommended for Delaware landscapes.


Photo from the Dow Gardens Archive, Dow Gardens, Bugwood.org.


Photo by Richard Webb, Self-employed horticulurist, Bugwood.org


Photo by Richard Webb, Self-employed horticulurist, Bugwood.org.




For more information on the 2009 UDBG Spring Plant Sale go to http://ag.udel.edu/udbg/events/annualsale.html

Nursery and Greenhouse - New Jersey Accepts DE Farm Tagged Vehicles

Greenhouses and nurseries in Delaware should be happy to note that New Jersey is now accepting Delaware Farm Tagged Vehicles. The following is more information.

DE and NJ Sign Reciprocity Agreement for Farm Vehicles to Cross State Line

It’s been an issue discussed at New Castle County Farm Bureau meetings and an issue on the minds of Delaware agriculture producers who haul their products across the Delaware state line into New Jersey. Until this past February, producers hauling agricultural products into NJ were required to have commercial vehicle registrations to cross the state line, which can cost significantly more than the Farm Vehicle registration (’FT’ tag) that is offered to Delaware ag producers who haul their own products within the state. Thanks to the efforts of Delaware Department of Agriculture, Delaware Department of Transportation, New Jersey Department of Agriculture and the New Jersey Motor Vehicle Commission, with this reciprocity agreement DE ag producers who haul their own products in their own properly State of Delaware-registered Farm Vehicles may now transport their product across the state line into New Jersey without a special permit or commercial tag (and vice versa).

I’ve talked to several producers who haul over the state line, and this agreement is a welcome one. In theory, this agreement allows properly tagged and licensed DE ag producers to drive across state lines without being stopped by law enforcement and being cited for violation. However, you can still be pulled over and cited for violation of New Jersey or Delaware transportation laws if you are out of compliance with current transportation regulations/requirements or your vehicle load is overweight. The truck enforcement units are out there.

It is a good idea to carry the reciprocity agreement with you when transporting across state lines. Until this agreement becomes well-known, you may still be stopped in NJ for having DE “FT” registered tags, and it’s a good idea to have the agreement in hand. The agreement can be found at: http://www.nj.gov/agriculture/divisions/md/pdf/mvcdelfarm.pdf

Along with the Farm Vehicle registration reciprocity, Delaware and New Jersey also signed a separate agreement so that now both states recognize each others’ commercial driver’s license exemption regulations for farmers. Meaning, if you have properly and legally acquired a valid driver’s license in Delaware and transport your own agricultural commodity in your own properly and legally registered farm vehicle, you are now exempt from obtaining a commercial driver’s license to haul into the state of New Jersey. This agreement may be found at: http://www.nj.gov/agriculture/divisions/md/pdf/delcdlfarmers.pdf

For more detailed information and specific information on NJ farm vehicle regulations see the following links: http://www.nj.gov/agriculture/news/press/2009/approved/press090218.html
www.nj.gov/agriculture/divisions/md/prog/farmermotorvehicles.html#8 .
For more detailed information on Delaware Department of Transportation code relating to farm vehicle regulations see the following link: http://regulations.delaware.gov/register/february2009/final/12%20DE%20Reg%201114%2002-01-09.htm

Anna Stoops, Extension Ag Agent, New Castle Co., email stoops@udel.edu

Friday, April 17, 2009

Landscape - Eastern Tent Caterpillar

The following is information on Eastern Tent Caterpillar, and insect pest you should be watching for in the landscape.

Our cool spring means that larvae are emerging from egg masses now (13-160 [59 peak] GDD ) and 50 migrating to tree branch forks to form tents. Caterpillars lay a trail of webbing down as they make their way to young leaves to feed. Eastern tent caterpillars are black with tan-colored hairs, irregular blue markings, a white stripe with a yellowish-tan stripe on either side down their back. They prefer to feed on wild cherry, but also readily eat crabapple, ornamental apple, plum, peach, and occasionally birch or ash. Caterpillars feed from 2-598 GDD or while Cornus florida is in full bloom before they mature 50 and leave the tree to search for a suitable location to pupate. The adults emerge in two to four weeks, mate, and females lay eggs in gray foam-like masses with about 150 350 eggs in a mass. Eastern tent caterpillars egg masses are usually laid on twigs or small branches and there is only one generation per year. A number of natural enemies such as assassin bugs, parasitoids, and birds help keep the insect under control. Pruning out egg masses and destroying the eggs in the fall or late winter before egg hatch is an effective cultural method to control eastern tent caterpillar. Some compounds used to control eastern tent caterpillar include: insecticidal soap, B. thuringiensis (Dipel), spinosad (Conserve), chlorantraniliprole (Acelepryn), or pyrethroid products such as bifenthrin. Apply when the larvae are small to increase efficacy and cover both the foliage and the tent.

Information from Brian Kunkel, Ornamental IPM Specialist, UD.

Landscape - Scale Insects: Indian Wax Scale

This is the 15th in a series on scale insects in the landscape. This post is on the Indian Wax Scale. Information is from the University of Maryland.

Indian Wax Scale (Ceroplastes ceriferus), Family Coccidae

Plants Damaged: This soft scale feeds on Chinese and Japanese hollies, azaleas, pyracantha, euonymus, boxwood, flowering quince, camellia, pear, azalea, persimmon, plum, barberry, and magnolia.

Damage Symptoms: This scale is large enough that its mere appearance is aesthetically unpleasing. Heavy populations can cause dieback of the infested plant.

Life Cycle: Females overwinter and eggs are laid in May in Maryland. Crawlers are active in early June. When crawlers emerge they will be yellow to pink in color and will excrete white wax that gives the scale a “cameo” appearance.

Monitoring: The adult females are red and covered with bright white gummy wax. Look for the large, very noticeable females overwintering on the stems.

Control: Horticultural oil does not work well on this scale. Distance applied when crawlers are present works well. Imidacloprid can also be applied as a soil drench in April. It takes 30 - 60 days for uptake into the stems of the plant. Soil application of dinotefuran (Safari) is uptaken in 2 – 3 weeks and should give good control.


Information from "Scales Commonly Encountered in Maryland Landscapes and Nurseries" by Stanton Gill, Extension Specialist in IPM for Nurseries and Greenhouses,and Suzanne Klick and Shannon Wadkins, Technicians, Central Maryland Research and Education Center University of Maryland Cooperative Extension.

Thursday, April 16, 2009

Nursery, Greenhouse, Turf, and Landscape - Soluble Salts

The following is information problems related to high soluble salts in landscapes, greenhouses, nurseries, and turf.

Each year we see plant damage in turf, landscapes, greenhouses, and nurseries due to high levels of soluble salts in soils or media. High soluble salts can come from a number of sources: deicing materials used in the winter; excessive fertilizer, manure, or compost use; “dumping” of fertilizer salts from certain slow release fertilizers; and irrigation water that is high in salts. Excessive soluble salts can result in reduced growth, loss of vigor, root death, yellowing of leaves, wilting, marginal leaf burn, or plant death. This occurs because soils or media with high salt levels make it more difficult for plants to take up water, or if very high will cause loss of water from roots. Foliage exposed to high salt levels will show symptoms similar to leaf scorch. There is also a potential for certain elements to become toxic in high salt conditions: examples would be sodium or ammonium.

A common problem is over application of fertilizers. This can occur with miscalculation of fertilizer rates or dilutions, poorly calibrated or malfunctioning fertilizer applicators or injectors, or excessive overlapping during application. All soluble fertilizer nutrients (nitrate, ammonium, potassium, calcium, magnesium, chloride, sodium, or sulfate ions), contribute to the soluble salt content of the soil or media. However, some soluble fertilizers have greater chance for salt injury than others. Refer to the salt index of a fertilizer to evaluate the potential to cause salt injury. Certain manures and composts can also contain high salt levels. In greenhouses or nurseries, salt levels often build up in media due to inadequate leaching or poor pot drainage. Dumping of salts from coated slow release fertilizers can also occur in greenhouse and nursery production, especially if fertilizer coatings were damaged in handling or by exposure to excess heat.

If you suspect high salts in soil or media, a soluble salt test should be done (the UD soil testing lab and other soils labs can do this test). Soluble salt content is determined with an electrical conductivity meter using a specified dilution of soil or media. An electrical conductivity meter is a useful instrument for growers, turf professionals and landscapers to have on hand for troubleshooting salt related problems.

Gordon Johnson, Extension Horticulture Agent, UD, Kent County

Landscape - Scale Insects: Winged Euonymus Scale

This is the 14th in a series on scale insects in the landscape. This post is on the Winged Euonymus Scale. Information is from the University of Maryland.

Winged Euonymus Scale (Lepidosaphes yanangicola (Kuwana)), Family Diaspididae

Plants Damaged: Mainly found on winged euonymus (Euonymus alatus), but the scale is reported feeding on maples, ash, lilac and willow.

Damage Symptoms: Yellowing of foliage and dieback of branched in heavy infestations. Heavily infested plants have been defoliated during the growing season.

Life cycle: Third instar females overwinter. Eggs are produced from late May to early June and are present through July. Females produce ‘crawler flaps’ (white edge) 2 - 3 weeks before crawlers emerge.

Monitoring: This scale tends to blend in with the corky ridges on the winged euonymus branches making detection more challenging until your eye is trained to pick up the scale covers.

Control: A mixture of 1% horticultural oil and Distance does a great job of controlling this scale. Dinotefuran (Safari) applied as a soil drench also works well.


Information from "Scales Commonly Encountered in Maryland Landscapes and Nurseries" by Stanton Gill, Extension Specialist in IPM for Nurseries and Greenhouses,and Suzanne Klick and Shannon Wadkins, Technicians, Central Maryland Research and Education Center University of Maryland Cooperative Extension.

Wednesday, April 15, 2009

Landscape - Scale Insects: Cryptomeria Scale

This is the 13th in a series on scale insects in the landscape. This post is on the Cryptomeria Scale. Information is from the University of Maryland.

Cryptomeria Scale (Aspidiotus cryptomeriae Kuwana), Family Diaspididae

Plants Damaged: This scale is found on many conifer species including fir, Cedrus, Chamaecyparis, rarely this scale is found on Cryptomeria, pine, spruce, Taxus and hemlock.

Damage Symptoms: As the scale draws out sap from the needles it causes a yellowing spotting of the foliage. Heavy infested plants are chlorotic. Dieback occurs when populations are high.

Life Cycle: This scale overwinters as second instar females. Adults occur in spring in March and April. Females lay eggs in June with crawlers appearing in June through early July. There are two generations per year. Adults of the second generation are present in July and crawlers are present in late August through September. Immatures overwinter on the needles.

Monitoring: Look for chlorotic foliage with yellow spotting or banding on the needles. Look for overwintering scale on the needles.

Control: A mixture of 1% horticultural oil and Distance does a great job of controlling this scale. Dinotefuran (Safari) applied as a soil drench also works well.


Information from "Scales Commonly Encountered in Maryland Landscapes and Nurseries" by Stanton Gill, Extension Specialist in IPM for Nurseries and Greenhouses,and Suzanne Klick and Shannon Wadkins, Technicians, Central Maryland Research and Education Center University of Maryland Cooperative Extension.

Tuesday, April 14, 2009

Greenhouse - Botrytis

Botrytis is a common problem in crowded greenhouses, especially during cloudy weather when plants are in bloom. The following is more information.

The extended period of cloudy weather has resulted in Botrytis Blight on closely spaced, tender spring annuals and herbs. Growers are all too familiar with the fuzzy grayish-brown spores (Gray Mold) that are easily spread on air currents and by water splash. Sometimes, less obvious symptoms show as tan colored cankers on stems that can cause entire branches of plants to wilt, such as Fuchsia hanging baskets, while the rest of the plant appears healthy. If left alone, more branches wilt one by one. Fuzzy spores will eventually form on stems deep inside the canopy.

Botrytis blight is best managed by combining environmental and cultural controls with chemical controls.

Environmental controls If you see active fungal sporulation, begin by first reducing the humidity in the greenhouse. Heat and vent in the evening (3x) and early in the morning to exhaust the moist, humid air and replace it with cooler, drier air.

Cultural controls Promptly removing severely infected plants, such as tender herbs, helps to reduce the disease pressure. Place severely infected plants that are covered with the grayish spores, in a plastic bag before removing from the greenhouse. This will help reduce potential spread of the easily airborne spores. Keep garbage cans covered so spores are not released into the greenhouse via air currents. Water early in the day, so foliage can dry rapidly. As plants are sold, provide more space to your existing crops to reduce humidity levels within your crops.

When Botrytis blight develops on herbs, cultural and environmental management is especially crucial because many of the fungicides labeled for ornamentals are not labeled for herbs.

Chemical Controls
Apply preventative fungicides before cutting back plants so the fungal spores are not released onto open wounds as workers handle plants. On ornamental crops, a number of fungicides are labeled for use against Botrytis Blight. The following are some of the fungicides listed under Botrytis management in The New England Recommendation Guide:

Azoxystrobin (Heritage), Bacillus subtillis (Rhapsody, Cease), chlorothalonil(Daconil, Echo and others), copper salts (Camelot), copper sulfate pentahydrate (Phyton 27), fenhexamid (Decree), fludioxonil (Medallion), iprodione (Chipco, 26GT and others), mancozeb (Dithane, Protect), polyoxin D zinc salt (Endorse), trifloxystrobin (Compass), and triflumizole (Terraguard). Combination products are also available containing some of these active ingredients.

Growers often rely on fenhexamid (Decree) which is a non-systemic fungicide with both protective and curative activity, chlorothalonil (Daconil) or iprodione (Chipco, 26 GT). Rotate among mode of action groups to delay the buildup of resistant strains. There are reports of widespread resistance to the benzimidazole fungicides (Cleary’s 3336 and Fungo Flo) as well as resistance to iprodione.

From the current issue of the New England Greenhouse Uptdate http://www.negreenhouseupdate.info/greenhouse_update/index.php

Landscape - Scale Insects: Calico Scale

This is the 12th in a series on scale insects in the landscape. This post is on the Calico Scale. Information is from the University of Maryland.

Calico Scale (Eulecanium cerasorum), Family Coccidae

Plants Damaged: Calico scale is a general feeder and can be found on many nursery and landscape plants including dogwood, honeylocust, magnolia, maple, sweet gum, tuliptree and ornamental fruit trees.

Damage Symptoms: Calico scale covers the branches and leaves of the host plant and feeds on the phloem tissue. The plant may be covered in sooty mold as a result of the large quantities of honeydew produced by the calico scale. In large numbers, feeding can result in branch dieback.

Identification: This white and dark brown calico scale is about 1/4 inch in diameter and is brightest when it reaches maturity and then darkens. First-instar nymphs start out pinkish and become yellowish as they enlarge. Overwintering Immature females are oval, flattened, and light to dark brown and have a hard waxy coating. Just before egg hatch the covering is white with gray-blue patterns.

Life Cycle: This scale overwinters as second instars and molts and matures to 3rd instars in early spring. The nymphs of this scale will migrate out onto the foliage in June and feed through the summer. In the fall the immatures will migrate back to the twigs where the females overwinter.

Monitoring: Look for copious amounts of honeydew in late May and early June. Look for the oval-shaped, yellow-bodied crawlers in June.

Control: Apply horticultural oil in March to early April to kill overwintering females. When crawlers are out, use 1% horticultural oil or Distance. Another option for controlling soft scale is to use a soil injection or soil drench of a systemic insecticide, such as imidacloprid or dinotefuran. This material takes 30 - 60 days to be taken up by the plant before it begins to control the scale. It is very effective against soft scale insects such as calico scale.



Information from "Scales Commonly Encountered in Maryland Landscapes and Nurseries" by Stanton Gill, Extension Specialist in IPM for Nurseries and Greenhouses,and Suzanne Klick and Shannon Wadkins, Technicians, Central Maryland Research and Education Center University of Maryland Cooperative Extension.

Monday, April 13, 2009

Landscape - Scale Insects: White Prunicola Scale

This is the eleventh in a series on scale insects in the landscape. This post is on the White Prunicola Scale. Information is from the University of Maryland.

White Prunicola Scale (Pseudaulacaspis prunicola), Family Diaspididae

Plants Damaged: This scale is commonly found on Prunus species but can also be seen on magnolia, ligustrum, rhododendron, forsythia, boxwood, and lilac.

Damage Symptoms: Dieback of twigs and yellowing of foliage

Life Cycle: Crawlers are present in May. A second generation occurs in July and a third in September. Crawlers appear about 2 weeks earlier than white peach scale. Crawlers are out in early May to June. Second generation crawlers are out from mid-July to mid-August. The third generation crawlers are out in September.

Monitoring: Both male and female crawlers are salmon colored.

Control: When crawlers are out, Distance mixed with 1% horticultural oil gives excellent control.

Information from "Scales Commonly Encountered in Maryland Landscapes and Nurseries" by Stanton Gill, Extension Specialist in IPM for Nurseries and Greenhouses,and Suzanne Klick and Shannon Wadkins, Technicians, Central Maryland Research and Education Center University of Maryland Cooperative Extension.

Sunday, April 12, 2009

Landscape - Rose Rosette Disease

The following is information on Rose Rosette disease which is thought to be a virus transmitted by the eriophyid mite.

Symptoms of rose rosette disease vary, but some of the more recognizable symptoms include rapid elongation of new shoots and witches' broom on small branches. Leaves are small, distorted, and may have a conspicuous red pigmentation. The red pigmentation is not a consistent symptom. Canes can develop excessive growth of unusually soft and pliable red or green thorns which may stiffen later. This excessive thorniness on the stems is diagnostic for rose rosette disease. Flowers may be distorted with fewer petals than normal, and flower color may be abnormal. Diseased plants may not exhibit all of these symptoms, especially in the early stages of the disease, so diagnosis can be difficult. The red pigmentation may be subtle and hard to distinguish from the normal reddish tinge of new leaves in spring. Monitor roses closely for symptoms to catch this disease as early as possible to help prevent its spread to nearby plants.

Control: Once a plant is infected there is no cure. The plant will die over the next 2 – 4 years. Plants that are showing all of the symptoms should be destroyed immediately. Some people try to control the eriophyid mite that spreads the disease. This involves applying Avid to the foliage every two weeks from May through October. This is obviously a lot of spraying. Forbid does have eriophyid mites on the label. It should provide control for at least 2- 3 weeks. You might be able to extend the spray intervals.

Rose rosette disease symptoms on leaves. Photo by James W. Amrine Jr., West Virginia University, Bugwood.org

Information from the April 10, 2009 edition of the TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers from the University of Maryland Cooperative Extension.

Landscape - Scale Insects: San Jose Scale

This is the tenth in a series on scale insects in the landscape. This post is on the San Jose Scale. Information is from the University of Maryland.

San Jose Scale (Quadraspidiotus perniciosus), Family Diaspididae

Plants Damaged: This armored scale can be found on apples, crabapples, and ornamental and edible plums, peaches and pears. It will also feed on cherry laurel, cotoneaster, pyracantha, rose, and other plants in the rose family.

Damage Symptoms: It feeds on the twigs and small branches and weakens the plant.
Yellowing of foliage and dieback of branches

Life Cycle: San Jose scale has three generations per year. The 3rd generation crawlers are still active in October. On apples the crawlers will move out onto the fruit in the first crawler emergence in May and during the second crawler emergence in July. The 3rd generation crawlers tend to be found on the twigs and branches and less on the fruit. On apples you will see round red circles on the fruit.

Monitoring: The female covers are light brown and round with a raised center. Examine
branches and twigs for the presence of overwintering female covers. Use a hand lens to examine foliage for presence of bright yellow crawlers which emerge in May and June.

Control: Target the crawler stage for the best control. Apply Distance and 1 % horticultural oil.


Information from "Scales Commonly Encountered in Maryland Landscapes and Nurseries" by Stanton Gill, Extension Specialist in IPM for Nurseries and Greenhouses,and Suzanne Klick and Shannon Wadkins, Technicians, Central Maryland Research and Education Center University of Maryland Cooperative Extension.

Saturday, April 11, 2009

Greenhouse - Geranium Pointers and Troubleshooting

The following are some pointers and troubleshooting hints for geranium production from the University of Maryland.

Sudden pH Drops:

Your geraniums may be humming along but make sure you are maintaining a correct pH level. If you let the pH fall off the plants will go downhill rapidly. Check your pH level at least weekly to detect any downward turns. There is a condition called sudden pH decline (SPD) where geranium crops growing at the optimum pH rapidly (1- 2 weeks) have the substrate pH shift downward 1 to 2 units. Taylor et al., 2008, reports that this occurs when phosphorus is deficient in the substrate and high temperatures cause stress of the geranium crops.

Proper pH:

The optimal pH varies by the type of geranium and root medium used. For zonal geraniums, the range for a soilless root medium is 5.8 to 6.2 and for a soil-based medium is 6.0 to 6.5. The optimal range is up to 0.3 units lower for ivy and regal geraniums (5.5 - 6.2). If modifications are required, the pH can be lowered with an acid-based fertilizer or acid injection. The pH can be increased with dolomitic limestone or hydrated lime.

Electrical Conductivity (EC):

The optimal EC range is 1.5 to 2.5 mS/cm for zonal and regal geraniums. Slightly lower levels are required by ivy geraniums, usually 1.0 – 2.0 mS/cm. Aphids on Geraniums: Monitor ivy geraniums for melon aphids and green peach aphids. We are seeing populations increasing in some greenhouses this week.
Control: Imidacloprid (Marathon), dinotefuran (Safari), Acetamiprid (TriStar), Endeavor, Aria, insecticidal soaps.

Diseases to watch out for on Geraniums:

One disease to watch out for on geraniums is bacterial leaf spot. This disease is caused by the bacterium Xanthomonas pelargonii and is especially prevalent in warm, wet weather where plants are grown in crowded conditions. Disease symptoms include small (pinhead size), circular or irregular, brown, sunken spots on older or lower leaves. Large numbers of spots will occur on a single leaf, these will coalesce and can kill a large portion of the leaf which will then drop off. As the disease moves through the plant, the lower leaves wilt and yellow. In severe cases, the stem will possess black stem cankers killing the upper portion of the stem. Leaves infected with bacterial leaf spot should be removed as soon as it is noticed. Severely infected plants should be removed.

Monitor for Botrytis leaf spot or blossom blight. It is caused by Botrytis cinerea. Botrytis is favored under cool, moist conditions or where plants are watered frequently. Leaves develop zonate, brown leaf lesions which develop a grayish brown mass of fungal spores. The lower leaves will yellow and rot. Flowers may also become infected. They show discolored petals which wilt and fall. Remove affected leaves and flowers. Maintain good air circulation in the greenhouse.

Reprinted from the April 3, 2009 edition of the Greenhouse TPM/IPM Bi-Weekly Report from the University of Maryland Cooperative Extension, Central Maryland Research and Education Center http://www.ipmnet.umd.edu/09Apr03G.pdf

Landscape - Scale Insects: Pine Needle Scale

This is the ninth in a series on scale insects in the landscape. This post is on the Pine Needle Scale. Information is from the University of Maryland.

Pine Needle Scale (Chionaspis pinifoliae (Fitch)), Family Diaspididae

Plants Damaged: Pine is the main host, but it has been observed on Abies (Spruce), Pseudotsuga, and Tsuga (hemlock).

Damage Symptoms: Yellowing of foliage and dieback of branches. This scale often exists in low levels on white pines but rarely reaches damaging levels.

Life Cycle: This scale overwinters as females and eggs. Crawlers are present in May. The secondgeneration occurs in mid summer with crawlers present from July through August.

Monitoring: When Sargent crabapple is in full bloom we can expect to see crawlers on pine needle scale. The reddish nymphs hatch in May and there is a second generation in July.

Control: Horticultural oil or Distance at crawler emergence. Dinotefuran (Safari) is reported to control this scale.


Information from "Scales Commonly Encountered in Maryland Landscapes and Nurseries" by Stanton Gill, Extension Specialist in IPM for Nurseries and Greenhouses,and Suzanne Klick and Shannon Wadkins, Technicians, Central Maryland Research and Education Center University of Maryland Cooperative Extension.

Friday, April 10, 2009

Turf - Fertilization in the Spring

The following is information on spring fertilization in turf from Virginia Tech.

There is no better money spent than to have a soil test done on the turf areas at least every third year. A soil test is the only way to determine if the soil needs lime, phosphorus (P) or potassium (K). Apply nutrients as recommended by a soil test and you’ll be taking a huge first step towards protecting water quality.

Nitrogen gets the most attention. The one nutrient that won’t be analyzed in a soil test is nitrogen (N). That is surprising since N is the focal point of turf fertility programs. The reason is that N levels change rapidly in a soil and test results usually have little meaning by the time you receive the report. The test results will provide recommendations on appropriate N application levels suitable for the grass and location.

Spring is one of the trickiest times to optimize N fertility. Cool-season grasses such as tall fescue or Kentucky bluegrass have their most significant period of root development in the spring, so some N is beneficial. High rates of N promote a lush, dark green lawn, but there is too much emphasis on shoot growth rather than roots, and this often leads to serious problems with disease, insects, or drought later in the year.

Warm-season grasses like bermudagrass or zoysiagrass don’t initiate much root growth until after shoot greening is complete, so the ideal scenario is to wait at least until 50-75% green-up before applying N. Excessive spring N fertilization that promotes a lot of warm season grass shoot growth can be disastrous to the turf if there is a late freeze.

Choosing a N source.

When selecting a fertilizer for the spring take a close look at the fertilizer label. It tells exactly what nutrients are contained in the product on a percent by weight basis and indicates the N release rate. Most garden fertilizers typically contain large amounts each of N, P, and K (e.g. 10-10-10, 19-19-19, etc.). The N in these sources is almost always entirely water soluble (WSN) and provides quick plant response. Specialty turf fertilizers contain high N percentages and lower levels of P and K (e.g. 29-3-7). This doesn’t mean the P and K aren’t needed by the plant, but history and experience show that repeated applications of garden fertilizers over the years results in soils testing high to very high in P and K. Unnecessary applications of P and K over time can ultimately result in water quality concerns (from excessive P) and nutrient imbalance (likely from excessive K).

Specialty turf fertilizers also often contain different forms of N that provide varying N-release rates and the label indicates the percentages of both WSN and water insoluble N (WIN) making up the total % N in the product. Organic fertilizers are usually very low N analyses (6-10% by weight) and are mostly WIN (often up to 85% of the total N). The higher the % WIN the more slowly available the N is to the plant by way of chemical and microbial reactions in the soil. Any source containing 50% or more WIN can be safely applied at higher application rates with minimal concern for nutrient leaching. However, understand this -- the plant does not care what the source is, only that its needs are met with appropriate application levels and timing.

N rates

The level of N depends on the fertilizer source, the grass, and area of the state. However, here are some basic guidelines. Fertilizer sources that contain more than 50% WIN can be applied up to 1.5 lbs N/1000 sq ft; those that are predominantly WSN should be applied at no more than 1 lb N/1000 sq ft. Recommended N levels from now through the end of May on cool-season grasses should not exceed a total of 1.5 lbs/1000 sq ft for Kentucky bluegrass, tall fescue, or perennial ryegrass, and no more than 1 lb for fine-leaf fescue. The rest of the recommended seasonal N fertility shouldn’t be applied until this fall. For warm-season grasses, allow some greening to occur before applying N, and resist the temptation to initiate standard N fertility programs of up to 1 lb N/1000 sq ft until the average last frost date has passed. Finally, consider that zoysiagrass performs best at 1-2 lbs N/1000 sq ft total per year, whereas bermudagrass can safely receive up to 3-4 lbs total.

Adapted from "Spring Lawn Fertilization—Getting it Right!" by Mike Goatley, Extension Turf Specialist/Associate Professor Crop & Soil Environmental Sciences, Virginia Tech. Go to http://www.weblogs.cals.vt.edu/lawn_garden/ for the podcast.

Landscape - Scale Insects: Oystershell Scale

This is the eighth in a series on scale insects in the landscape. This post is on the Oystershell Scale. Information is from the University of Maryland.

Oystershell Scale (Lepidosaphes ulmi (Linnaeus)), Family Diaspididae

Plants Damaged: This scale is a general feeder (polyphagous) and is reported on 85 host plants in 33 families. We have observed it commonly on Acer (maples), Amelanchier (serviceberry), Cercis (redbud), Crataegus (hawthorn), Quercus (oak), and Prunus spp., but is found on many additional species.

Damage Symptoms: Yellowing of foliage and dieback of branches.

Life Cycle: There are univoltine and bivoltine forms found in Maryland. Bivoltine forms have crawlers present in April. Crawlers of the univoltine form are present from May through June.

Monitoring: The adult females of this armored scale look like elongated oysters.

Control: Horticultural oil or Distance at crawler emergence.


Information from "Scales Commonly Encountered in Maryland Landscapes and Nurseries" by Stanton Gill, Extension Specialist in IPM for Nurseries and Greenhouses,and Suzanne Klick and Shannon Wadkins, Technicians, Central Maryland Research and Education Center University of Maryland Cooperative Extension.

Thursday, April 9, 2009

Landscape and Nursery - Plants for Delaware Landscapes Featured at the 2009 UDBG Spring Plant Sale #18

This year, the University of Delaware Botanic Garden spring benefit plant sale features those plants that add to the biodiversity of the landscape and offer food and habitat for wildlife, especially insects and the birds that eat them. Many native plants are featured. This is the 18th in a series on plants being offered at the UDBG spring plant sale that are recommended for Delaware landscapes.

Elderberry. Photo by Richard Webb, Self-employed horticulurist, Bugwood.org.


Carolina Rose. Photo by John D. Byrd, Mississippi State University, Bugwood.org.


Lowbush Blueberry. Photo by R.A. Howard. ©Smithsonian Institution. Courtesy of Smithsonian Institution, Richard A. Howard Photograph Collection. United States, ME.




For more information on the 2009 UDBG Spring Plant Sale go to http://ag.udel.edu/udbg/events/annualsale.html