1 TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers Commercial Horticulture April 6, 2012 In This Issue... - Cold weather impact - Boxwood blight - Powdery mildew and cold damage on turf - Asian longhorned beetle - Boxwood leafminer - Spring container and landscape fertility management - Japanese maple scale - Scale on willow oak - Euonymus leafnotcher caterpillar - Boxwood psyllid and cold damage - Aphids - Hemlock woolly adelgid - Ambrosia beetles Weed of the Week Plant of the Week Phenology Degree Days Contacts for Experts Conferences Integrated Pest Management for Commercial Horticulture If you work for a commercial horticultural business in the area, you can report insect, disease, weed or cultural plant problems found in the landscape or nursery to Coordinator Weekly IPM report: Stanton Gill, Extension Specialist, IPM for Nursery, Greenhouse and Managed Landscapes, (office) or (cell) Regular Contributors: Pest and Beneficial Insect Information: Stanton Gill and Paula Shrewsbury (Extension Specialists) and Brian Clark (Extension Educator, Prince George s County) Disease Information: Karen Rane (Plant Pathologist) and David Clement (Extension Specialist) Weed of the Week: Chuck Schuster (Extension Educator, Montgomery County) Cultural Information: Ginny Rosenkranz (Extension Educator, Wicomico/ Worcester/Somerset Counties) Fertility Management: Andrew Ristvey (Regional Specialist, Wye Research & Education Center) Design, Layout and Editing: Suzanne Klick (Technician, CMREC) Cold Weather Impact Felt This Week We are receiving reports of hydrangea, spirea, aucuba, and many other landscape plants that had flushed out new growth in the warmth of March and are now showing cold damage. The temperatures dipped from a low of F from the Eastern Shore to the Western Shore of Maryland on March 26, followed by temperatures in low the 30 F range on March 27th. The soft new growth on many plants are blackening and curling. Some people are mistaking this damage for Botrytis on tip growth. Prune out the dying tips. We may see more of this damage since on April 2 the temperature dipped down again into the low 30 F range in many parts of the state. New Host Reported For Boxwood Blight The Connecticut Agricultural Experiment Station recently identified Pachysandra terminalis (Japanese pachysandra/spurge) as a new host for Cylindrocladium pseudonaviculaturm, the fungus that causes Boxwood Blight. Healthy plants were inoculated with spores and lesions developed ten days later. More testing needs to be done to determine if other species are also susceptible to this pathogen. Boxwood and pachysandra are both in the Boxwood (Buxaceae) family. This information with photos is available at: Thus far, this disease has been confirmed in Ohio (the most recent find in March 2012), North Carolina, Connecticut, Virginia, Maryland, Pennsylvania, New York, Rhode Island, Massachusetts and Oregon.
2 Powdery Mildew On Turf Mary Kay Malinoski, HGIC, is reporting powdery mildew on turf in Catonsville. Conditions for the development of this pathogen are reduced air circulation, high relative humidity, low light conditions (such as shade or extended cloud cover) and temperatures between 60 and 70 F. It is not a big problem so control is usually not needed. Cold Damage On Turf Dave Young is seeing tips of turf blades turning black and dropping off after the first flush of growth this spring. Asian Longhorned Borer On Monday April 2nd, I (Stanton) went up to Longwood Gardens for the Sentinel Tree training session on the new pheromone traps for Asian longhorned borer. We will be trying out a couple of these traps at CMREC and another location this season. The bait is ground up maple leaves extracts mixed with male ALB pheromone sold by ChemTica company. Several Mid-West and East Coast arboretums are working with Dr. Melody Keena and Dr. Kelli Hoover on collecting data from these traps placed in arboretums and surrounding neighborhoods. They are also testing the trap out in China this summer. An ALB Update: In the Worcester, Massachusetts area they have quarantined over 110 square miles of area and identified 21,000 infested trees. In the fall of 2011, ALB was found in Ohio in a town called Bethol, which is in Clement County, Ohio. So far they have found ALB in an area covering 56 square miles and identified 7,056 infested trees. The infestation is thought to have arrived in wood packing crates delivered to a winery in Bethol, Ohio. The interesting part is an international law was passed back in 2002 that outlines standards that countries are supposed to follow in treating products and packing materials before shipping. The find in Ohio is thought to have occurred after Unfortunately something not properly treated must have slipped through. The Asian longhorned borer is known to feed on over 25 species of trees. American red maple, sugar maple, silver maple, Norway maple, and sycamore maple are their preferred hosts. Elm, birch, black willow, silk tree and Katsura are also favored by the beetles. They just found it infesting goldenrain trees in Ohio which is a new host to add to the list. The interesting thing is that even though the female beetle lays eggs into goldenrain tree, researchers found that the tree produces a huge amount of sap that drowns most of the larvae. Asian longhorned beetle exit hole Photo: Dennis Haugen, USDA Forest Service, Bugwood.org Researchers are working with detection dogs for ALB infested trees. They can detect the frass pushed out of the galleries but after 20 minutes they have to pull the dogs off or they become oversaturated with the smells and stop being effective. Asian longhorned beetle adult If you find damage or the beetle this year please get a sample to Extension faculty or the MDA. 2
3 Boxwood Leafminer Paul Wolfe, Integrated Tree Care, called on Monday (4/2) to report adult flight activity of boxwood leafminer in the Chevy Chase Circle area of Montgomery County. Tony Murdock is also finding activity in Frederick and Walkersville this week. So far, adults are not active here at the research center Ellicott City (most are in the pupal stage and there are few larvae being found after breaking open the leaves to check the life stage). We are seeing more and more damage from leafminer show up as samples submitted to us. It seems boxwood plantings are increasing in urban landscapes. Boxwood leafminer adult Spring Container and Landscape Management, Andrew Ristvey This season has come early for all of us and we are scrambling to manage our plants a couple weeks earlier than expected and hoping that we are done with freezing temperatures that will harm our freshly budding plant material. And who knows what type of summer this is going to be? This is a good time to remind you about fertility management for both containerized plants and landscaping systems. Be mindful of the temperatures past and future. If you have overwintered containers that were top-dressed with fertilizer, those warm winter days would have promoted nutrient release. At this time, those top-dressed fertilizers may be out of charge or your media is full of salts if you had not been able to irrigate. You should start to monitor EC s if you have not already. If you have not done so already, dust off your EC meters and make sure they are working and calibrate them. Then, check to see if you have any salts in your pots with a pour-through or a saturated media extract. Roots are now actively growing in your containers so they may need some nutrients. For landscapers, you may want to get soil tests for your new beds and the old beds that you are maintaining. Do so for each bed where practical. Take several sub-samples within a bed at 6 to 8 inches, mix them in a bucket and take a sample. End them off to a reputable lab. Make sure that you ask for tests which include the full spectrum of analyses including organic content, ph, Cation Exchange Capacity (CEC), and all the essential nutrients. When developing new beds, note the species you are planting. Try to keep species of similar soil requirements in the same bed to make soil management easy. Fertilize with the correct nitrogen source. Ericaceous species do not use nitrate so there is no sense in fertilizing azaleas with nitrate based fertilizers. For the other species, your soil chemistry will determine your nitrogen form ratio. In low ph soils, the use of nitrate based fertilizer would help in bring soil ph up for plants that like soil a little sweeter. Do not use aluminum sulfate to acidify a soil unless you are trying to make the big leaf hydrangeas blue. Use an ammonium based fertilizer or sulfur coated urea, or an amendment like agricultural grade sulfur or iron sulfate for soils with low iron availability. If you have any questions about monitoring methods or the results of your analyses, feel free to call me at x 113. Japanese Maple Scale We were conducting a field trial on Japanese maple scale in College Park and were taking samples on Tuesday of this week. We dragged branches back to the lab to see what life stage the scale were in at this point. We found only 3rd instar females present. No evidence of eggs yet. Other Scales: As we move into later April please send me (Stanton Gill) scale samples from landscapes and nurseries so we can see what stage they are in and publish the findings in the weekly IPM Alert. Thanks. 3
4 Scale On Willow Oak Steve Frank, North Carolina State University, sent photos of Eriococcus quercus (oak felt scale) on willow oak. The crawlers were just coming out in his area. We are usually about 3 weeks behind this part of North Carolina so you can watch for this scale on willow oaks as we move into early May. Control: Distance or Talus can be used to control crawlers. Eriococcus quercus scale on willow oak (left); showing crawlers (right) Photos: Steve Frank, North Carolina State University Euonymus Leafnotcher Caterpillar (Pryeria sinica) Damian Varga, Scientific Plant Service, reported heavy infestations of the euonymus leafnotcher caterpillar at multiple sites in Severna Park this week. Craig Hudson, Evergreen Genes, Inc., received reports from his customers this week that they are doing plenty of damage on euonymus plants in Glen Burnie. Dick Bean, Maryland Department of Agriculture, sent an pointing out that this caterpillar was also found in Bowie in Please let Dick Bean know if you are seeing this caterpillar in areas beyond where it has already been reported. Control: Options include Conserve (spinosad) and Confirm (tebufenozide). Euonymus leafnotcher caterpillar Boxwood Psyllid We received additional reports of boxwood psyllid activity on boxwood plants in the area. Bernie Mihm, Fine Earth, found them active on Boxwood microphylla var. korena Winter Gem and Carol Allen is finding psyllids as well as cold damage on boxwood. Control: The damage is Boxwood psyllid (left) and cold damage very insignificant in that it only causes new growth to cup slightly (above) so control is usually not necessary. If you do decide to treat, any Photos: Carol Allen of the neonicotinoids such as imidacloprid (Merit) or dinotefuran (Safari) can be applied as a soil drench. The drench needs to be made 1 3 months before pest activity. At this point, TriStar as foliar spray or Orthene can be used. 4
5 Aphids On Landscape Plants Richard Anacker, A&A Tree Experts, Inc., reported spiraea aphids on spirea this week in Clarksville. There are melon aphids on sedum plants here at the research center in Ellicott City. One sign that aphids are present is high ant activity on the plant. The ants protect the aphids from predators and feed on the honeydew secreted by the aphids. Control: Be sure to check for predator activity on these plants. Monitor aphid populations to determine if control is necessary. Control materials include insecticidal soap and horticultural oil. Consult the Extension perennial manual at for additional options. Spirea aphids Melon aphids on sedum Hemlock Woolly Adelgid Hemlock woolly adelgids are in the egg stage here at the research center. The eggs are found within the white cottony sacs that are on the plants. Monitoring: Look for eggs under this wax and then the reddish brown crawlers. Crawlers are usually active in this area starting in late April or early May. With the recent warm weather, they might become active a bit earlier this year. Control: Small trees (under 20 ft) that can be thoroughly covered with a spray can have an application of 2% horticultural oil or insecticidal soap applied to crawlers or newly settled crawlers. Acetamiprid (Tristar) can be applied as a foliar spray. Imidacloprid (Merit) can be applied as a soil drench or soil injection. It takes 60 days for imidacloprid to become toxic in the plant before controlling the pest. Make sure the soil has adequate soil moisture Cottony eggs sacs of hemlock woolly adelgid at the time of application. Do not apply imidacloprid during drought conditions unless the area is thoroughly irrigated after an application. Applications can be made in the fall or early spring. Dinotefuran (Safari) can be applied as a soil drench. It takes about 2-3 weeks for uptake of dinotefuran. Ambrosia Beetles Ambrosia beetles continue to be active drilling into trees. No Xylosandrus species were found in insect samples from a trap sent by Tony Murdock, Fine Pruning, from Frederick this week. Marie Rojas, IPM scout, is reporting them drilling into a crabapple. 5
6 Weed of the Week, Chuck Schuster Correction from March 30th report: I made a mistake in the Latin name last week. The name should have been Viola rafinesquii, named after the botanist Rafinesque. Thanks to Alice for catching that and keeping me accurate. Our weed of the week this week is roughstalk bluegrass, Poa Trivialis. This perennial weed is found in turf and has been appearing in some of our well managed turf areas this spring. It is classified as a fine textured, cool season turf with a prostrate spreading growth habit. Roughstalk bluegrass will spread quickly by way of stolons which can be a problem for the desirable turf species. It reaches a total height of up to three feet, and has a panicle seedhead which is typical of other bluegrass species. As weather gets hotter it will go into a dormant stage, returning to active growth when the temperature moderates and then it will grow through the cooler months. The stems have bands of purple at each node and small hairs. Leaves have the boat-shaped tip found in most bluegrass species, are a shiny light green color, and may discolor to a bronze when stressed by heat or drought. Each leaf blade can grow up to seven inches in length and one quarter inch wide. Leaf blades are covered with small hairs. It also has a large, membranous ligule. This weed can be infected with dollar spot and brown patch disease. Control of this weed is difficult in established turf. Velocity herbicide is labeled for it. It should be noted that in some stands of established turf, recent weather conditions has caused it to show some frost damage or bleaching of the blades. Plant of the Week, Ginny Rosenkranz Quercus palustris, pin oak or swamp oak, is a native tree with a distinctive branching habit. The lower branches bend down towards the ground, the middle branches grow level to the ground and the top third of the branches grow upwards toward the sun. A true forest tree and a very fast growing tree, pin oaks can grow feet tall and spread from feet wide. The branches are small compared to the white oak, and dense, and with the upright, level and downward sloping branches, it creates a silhouette of a green pyramid. The bark of pin oak is thin, smooth and gray brown in color that develops shallow ridges and furrows as it ages. The glossy dark green leaves are arranged in an alternate fashion and have a deep u-shaped sinus and slender pointed lobes. The fibrous root system prefers moist, 6 Roughstalk grass Photo: Penn State Turfgrass Pin oak showing lower branch habit Photo: Ginny Rosenkranz, UME rich, and well drained acidic soils, but the tree will grow in wet soils and is slightly tolerant of dry sandy soils, city conditions and sulfur dioxide pollution. New cultivars like Crownright and Sovereign have a more level branching system that doesn t allow the lower limbs to sweep to the ground. Oak galls can be a problem when the trees are stressed by drought, but at this time the emerald ash borer and the Asian longhorned beetle are not among the pests.
7 Plant Phenology: What s in bloom PLANT PLANT STAGE (Bud with color, First LOCATION bloom, Full bloom, First leaf) Berberis thunbergii First bloom (March 31) Columbia Erythronium americanum (trout lily) First bloom (April 2) Columbia Podophyllum peltaum (mayapple) First leaf (March 24) Columbia Degree Days (As of April 5) Baltimore, MD (BWI) 228 Dulles Airport 240 Frostburg, MD 137 Martinsburg, WV 220 National Arboretum 288 Reagan National 321 Salisbury 403 Who can you contact for help with plant problems? Diseases: Karen Rane: Go to for information on how and where to submit suspected disease samples to her lab. Insects: Stanton Gill: (cell) or (office) Paula Shrewsbury: Brian Clark: (Brian covers Prince George s County) Weeds: Chuck Schuster: Soil Substrates Plant Fertility: Andrew Ristvey: Horticulture: Ginny Rosenkranz: ext 106 (Wicomico, Worcester and Somerset counties) NURSERY and GREENHOUSE Grower Nutrient Management Plan Certification Training Wednesday, April 11, 2012, 9am - 3pm. Attend this session if you need to become certified to write and update your own Nutrient Management plan. Location: Wye Research and Education Center, 124 Wye Narrows Drive, Queenstown, MD For registration information, please contact Debby Dant X115, For program information, contact Andrew Ristvey, or John Lea-Cox, NOTE: There is no cost for this program, but you need to confirm attendance since Extension will provide lunch. 7
8 Upcoming Programs May 23, :30-3:15 Invasive Species Identification and Management Seminar Location: Government Center Parkway, Fairfax, VA Cost: Free, but registration is required. To register please go to: Contact: Jack Baggett , fairfaxcounty.gov ASCFG Mid-Atlantic Regional Meeting June 18, 2012 Roost Flowers and Design Location: Virginia Beach, Virginia ascfg.org 2012 Perennial Plant Symposium July 4-10, 2012 Location: Boston, Massachusetts perennialplant.org OFA Short Course July 14-17, 2012 Location: Columbus, Ohio ofa.org OFA Perennial Production Conference September 10-12, 2012 Location: Grand Rapids, Michigan ofa.org CONTRIBUTORS: Stanton Gill Extension Specialist Paula Shrewsbury Extension Specialist Karen Rane Plant Pathologist Chuck Schuster Extension Educator Ginny Rosenkranz Extension Educator David Clement Plant Pathologist hgic.umd.edu Andrew Ristvey Extension Specialist Brian Clark Extension Educator Thank you to the Maryland Arborist Association, the Landscape Contractors Association of MD, D.C. and VA, the Maryland Nursery and Landscape Association, Professional Grounds Management Society, and FALCAN for your financial support in making these weekly reports possible. Photos are by Suzanne Klick or Stanton Gill unless stated otherwise. The information given herein is supplied with the understanding that no discrimination is intended and no endorsement by University of Maryland Extension is implied. University of Maryland Extension programs are open to all citizens without regard to race, color, gender, disability, religion, age, sexual orientation, marital or parental status, or national origin.