TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers Commercial Horticulture April 5, 2013 In This Issue... - Degree days - Warming trend? - Horticultural oil - Cherry laurels - Ambrosia beetles - Euonymus leaf-notcher caterpillar - Lawn damage - Eastern tent caterpillars - Tar spot on holly - Gymnosporangium rusts - Pests on fruit - Lawn fertilization certification training Beneficial of the Week Weed of the Week Plant of the Week Degree Days Contacts for Questions Conferences Integrated Pest Management for Commercial Horticulture ipmnet.umd.edu Conferences Publications Archived IPM reports 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 sklick@umd.edu Coordinator Weekly IPM report: Stanton Gill, Extension Specialist, IPM for Nursery, Greenhouse and Managed Landscapes, sgill@umd.edu. 301-596-9413 (office) or 410-868-9400 (cell) Regular Contributors: Pest and Beneficial Insect Information: Stanton Gill and Paula Shrewsbury (Extension Specialists) 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) Low Degree Days When you look at the end of the weekly IPM report you will see that the accumulated degree days are still relatively low with College Park at 31 and near our CMREC facility it is still around 8 accumulated degree days. It is staying consistently cool this spring and we are seeing very little insect activity so far. Mark Daughtrey, Chapel Valley Landscape, said he was looking at old records of late snow fall and he reported that back in 1944 there was over 30 of snow on April 15th. I guess you can count your blessings that at least it is not snowing yet. Warming Trend? Next week, it is finally predicted to warm up a bit. In Washington, they pushed back the peak cherry blossom bloom time to April 6th to the 10th. We should see local trees pushing out flowers in the next week or so. Daffodils in bloom on April 5, 2013
Horticultural Oil The good news is that most plants are still very dormant so you have plenty of opportunity to make dormant applications of horticultural oil to kill scale insects and mites that overwinter as eggs such as boxwood mites, southern red mites, locust mite, and European red mite. For the dormant oil applications to be effective, we need 4 or 5 days with daytime temperatures above 50-55 F so insect respiration rates are up. Boxwood are everywhere in the landscape and we are getting more reports of boxwood mite damage, especially if boxwoods are growing in full sun. The upright, columnar boxwoods also appear to be more prone to boxwood mite injury. The boxwood mite overwinters as eggs and they should be hatching sometime in April. If you observe hatching in your area contact Stanton at 410-868-9400 or sgill@umd.edu. Why Are There So Many Cherry Laurel? By: Stanton Gill Before I answer this question, let s look at one of the growing urban pests deer. Deer populations continue to be out of control in many urban areas which results in a limited landscape palate in many urban and suburban landscapes. Last Friday, I paused on a roadway in Howard County to let a deer run across the road. It was good that I hit the brakes because 15 additional deer crossed after the first one. I started forward and noticed another 7 8 deer trying to cross with the herd. The herd was heading right into a nursery field. At a talk for LCA in Chevy Chase in January, I showed a picture of cherry laurel that was heavily infested with white pruincola scale. This scale has really taken off in the last 3 years in landscapes and is causing a lot of damage. I suggested that people might want to consider using some other plant. The next speaker spoke about boxwood blight and they in-turn told the audience that they might want to consider not planting boxwood. During the break, several people came up to me to explain that the reason many landscape designers and architects are putting boxwood and cherry laurels into landscapes is that they are the most resistant to deer browsing. Since we cannot get rid of the deer in urban settings very efficiently, then we are going to have to closely monitor cherry laurel for white pruincola scale and main peach tree borer if they are going to continue to be used in landscapes. Both pests are growing in numbers of reported activity that we are receiving. For boxwood, you will have Cherry laurel in bloom Photo: Robert Vidéki, Doronicum Kft., Bugwood.org to monitor closely for symptoms of boxwood blight and destroy any plants that start to show symptoms. These solutions are not easy ones, but we meet the challenge with regular monitoring. Ambrosia Beetle Update We set traps out at the research center here in Ellicott City last week. As of today, there are no beetles in the traps. There are also traps being set out in Barnseville, Frederick, and Salisbury. Next week, with temperatures going into the upper 60s and low 70s, we will send out a special report earlier in the week if we see anything. When the ambrosia beetles are active, Onyx (bifenthrin) is labeled for use in the nursery and landscape, and Astro is labeled for landscape use. Let us know and send a photo (sgill@umd.edu) if you see wet areas on trunks. Ambrosia beetle activity is later this year, but with warmer weather next week, it won t be long before we see them. 2
Euonymus Leaf-notcher Caterpillar (Pryeria sinica) Activity of early instar euonymus leaf-notcher caterpillars was reported last week. Look for eggs and early instars of this caterpillar now. This caterpillar has been reported in Anne Arundel, Prince George s and Baltimore counties. If you see this caterpillar in other areas, please let MDA know. Control: Since the damage occurs early in the season, control is not always necessary. There is only one generation of this pest and plants can recoup. If you decide to treat, control options include Conserve (spinosad), Talstar (bifenthrin), and Orthene (acephate). Bt is effective only when the caterpillars are small. Note: There is another caterpillar, called the euonymus caterpillar (Yponomeuta cagnagella), that is active later in the season in May and June. Euonymus leaf-notcher eggs along stem (above) and caterpillars and damage (below) Photo: Eric R. Day, Virginia Polytechnic Institute and State University, Bugwood.org Tracks And Holes in the Lawn Last week when we had the surprise snow storm some areas had around 3-5 inches of snow. While the snow was on the ground, voles had a heyday, making shallow tunnels between the snow and the soft ground. There were several burrow holes that they started and then stopped making when the snow melted. They left unnatural looking serpentine half circle tracks through the soft soil. Your customers may ask what is making the tunnels and holes in their turf areas. Erik Goerner, Maxalea, sent us this photo of a China Girl holly stem with damage from probably either a vole or rabbit. The damage was on a holly in a customer s landscape. Eastern Tent Caterpillars Ginny Rosenkranz, UME, sent in a photo showing the recent hatch of eastern tent caterpillars on the Eastern Shore on April 3. Hatching activity will increase as temperatures warm up over the few weeks. Control: Remove and destroy the tents. Bacillus thuringiensis (Bt) can be used on young caterpillars. Other options include Confirm (tebufenozide), Acelepryn (chlorantraniliprole), and Conserve (spinosad). Eastern tent caterpillars Photo: Ginny Rosenkranz, UME 3
Tar Spot on Holly Chad Vrany, Bartlett Tree Exeperts, reported tar spot on American holly in Ruxton. The diagnosis was confirmed by Bartlett Labs. Leaf spots are yellow in spring, turn red-brown in summer and become the characteristic dark tar spot by fall. Management: Maintaining healthy plants, removing infeced leaves and pruning to increase air movement can help to reduce the incidence of this disease. Treatment is usually not necessary. Tar spot on holly Photo: Chad Vrany, Bartlett Tree Experts Gymnosporangium Rusts (Cedar-apple, Cedar-quince, and Cedar-hawthorn Rusts) David Clement checked rust galls on juniper late this week and reported that the galls are still tight and there are no signs of sporulation yet on the plants he scouted in Ellicott City. As it warms up next week, monitor galls on Juniperus spp. hosts and look for the start of the dry-looking, orange telial horns which will develop into the gelatinous horns containing the teliospores during cool, wet periods in spring. These teliospores germinate and produce the basidiospores which infect rosaceous plants (which rosaceous plant(s) infected is dependent on the particular gymnosporangium rust present). Management: Timing is critical for good control on the rosaceous hosts (apple, hawthorn, etc). If deemed necessary, fungicide sprays have to be applied when spores are being shed from the junipers, usually starting in mid-march, but this year it s occurring a bit later in many areas. No chemical control is usually advised to prevent infection of the junipers. Infection of the junipers is happening all summer and into the fall from spores produced on the roseaceous hosts which would require many sprays all season. The period during which the rosaceous plants are infected is short (March/early April through May). Spray susceptible crabapples, apples, quince and hawthorn with Mancozeb (Cleary Protect TO), Fore (Dithane, Mancozeb), Chlorothalonil (Daconil Ultrex), Triadimefon (Bayleton, Strike) or propiconazole (BannerMaxx). It is the user s responsibility to follow all label instructions on rates, spray intervals and safety. Fungicides suppress, but do not control this disease. It may not be feasible, but if you see the galls on junipers during the winter, pruning to remove the galls helps to reduce the spread of this disease. When planting trees, look for plants with resistance to these rust diseases. Rust gall in the tight stage (above) and one with the start of the telial horns (right) Cedar-apple rust gelatinous horns Photo: Joseph O Brien, USDA Forest Service, Bugwood.org 4
Diseases on Home Fruit Some of you have reported that your customers want to know about disease activity on home fruit plantings. Next week, many apple varieties will move into the green tip stage. If you are planning on applying a protective fungicide for rust or apple scab such as Manzate or Captan (both labeled for home fruit), then make an application in the next couple of days. Control of Brown Marmorated Stink Bug on Home Fruit Plantings: Susan Trice, Master Gardener Coordinator, Frederick County, asked about what homeowners can use on home fruit plantings to control brown marmorated stink bugs. Jon Traunfeld, HGIC, researched this information and found the following is labeled for home fruit: Do It Best Lawn and Garden Insect Control Concentrate (tree fruit only); a.i.: permethrin Ortho Basic Solution Lawn and Garden Insect Killer Concentrate (tree fruit only); a.i.: permethrin Ortho Fruit & Vegetable Insect Killer Ready-Spray II - tree fruit, blueberry, strawberry; a.i.: acetamiprid *There are also several homeowner products with neem or pyrethrins labeled to control pests on specific types of fruit. Training for Lawn Fertilization Certification in Maryland Maryland s new Fertilizer Law is designed to protect the Chesapeake Bay from excess nutrients entering its waters from a variety of urban sources, including golf courses, parks, recreation areas, athletic fields, businesses and hundreds of thousands of suburban and urban lawns. Nutrients, primarily nitrogen and phosphorus, are key ingredients in lawn fertilizer. When it rains, excess nutrients can wash off the land and into the streams and rivers that feed the Chesapeake Bay. Once in our waterways, excess fertilizers fuel the growth of algae blooms that block sunlight from reaching Bay grasses, rob the water of oxygen and threaten underwater life. Lawn fertilizer now accounts for approximately 44% of the fertilizer sold in Maryland. While certain restrictions on fertilizer use have been in place for farmers since 2001, additional stakeholder involvement is needed if Maryland is to meet the new nutrient reduction goals outlined in its Watershed Implementation Plan (WIP) to restore the Bay. Maryland s new lawn fertilizer law affects fertilizer manufacturers and distributors, lawn care professionals and homeowners. Beginning October 2013, all lawn care professionals must be certified in order to apply fertilizer in Maryland. Once the exam is taken and passed, then the license will be good for a calendar year. Re-certification conferences will be offered so people can renew their license. At this point you must obtain 2 nutrient management credits to renew the license. MDA has information posted on this law at: http://mda2.maryland.gov/resource_conservation/pages/fertilizer.aspx The University of Maryland Extension, Montgomery County is offering a 4 hour program for Lawn Fertilization Certification in Maryland on April 16, 2013 at the Montgomery County UME Office from 9:00 am 1:00 pm. Cost will be $20.00 per person Contact Chuck Schuster at cfs@umd.edu or call 301-590-2807 to register 5
Beneficial of the Week, Paula Shrewsbury An interesting parasitoid found by graduate students. While searching the UMD campus this week for larval insects for her Larval Identification course collection, Ashley Jones came across an interesting insect on holly foliage. Her classmate, Chris Taylor, helped to identify what turned out to be a pretty interesting parasitoid. One I had never observed before. First, let us start with the host (or food item), an herbivore in the family Flatidae (order Hemiptera). Flatids are a family of planthoppers. They have sucking mouthparts and produce abundant amounts of white wax. Flatids have a wide host range, though I most often see them lining the stems plants such as hosta and other perennials. The parasitoid, a wasp (order Hymenoptera) in the family Dryinidae, was found on holly leaves that also had exo-skeletons of flatid insects. We saw flat, oval, clear cocoon-like structures on the underside of the holly leaves and when we pulled apart the cocoons we found live larvae of the Dryinid parasitoid. The life cycle of Dryinids is interesting. Many overwinter as diapausing (similar to hibernation) larvae inside the silky cocoon as the ones we found. The adults emerge in June where males feed on sugar sources (likely nectar or honeydew) and only live a few days but long enough to mate with females. The females live longer and they may feed on planthopper nymphs directly, this is referred to as host feeding and usually results in death of the planthopper, or they may parasitize planthopper nymphs, also ultimately resulting in death of the planthopper. These parasitoids are what are referred to as ecto-parasitoids. The adult wasp lays an egg in a specific location on the outside of the planthopper (between the wing pads of the nymphs). Within a few days the egg hatches and the larva attaches itself to its host with its mouthparts and feeds. The larvae actually develop externally of the host, looking like a cyst protruding from the planthopper. When ready to pupate the larvae removes itself from the host and spins a silky cocoon under the dead body of the planthopper. Here it completes its development and then goes into diapause for the winter. Some species of Dryinid parasitoids have 2 generations a year. A related species of Dryinid parasitoid native to North America has been used in a classical biological control program in several countries in Europe where it was successfully released in several urban areas to control a flatid planthopper pest. The Dyinid A Flatid planthopper nymph and the wax it produces on a plant stem Photo: Paula Shrewsbury, UMD parasitoids in this biological control program were originally collected from Connecticut and Texas. It is nice to see that Dryinid parasitoids are doing their job here in Maryland too. Information for this article came from: Trivellone, V., C. Nali, and A. Lucchi. 2006. ENTOMOLOGICAL NEWS 117 (2): 125. 6 The Dryinid parasitoid larva under its cocoon. Note you can see the eyes (left side of larva) Photo: Paula Shrewsbury, UMD Flatid planthopper exoskeletons and the silky cocoons of the Dryinid wasp larvae Photo: Paula Shrewsbury, UMD
Weed of the Week, Chuck Schuster Blue mustard, Chorispora tenella, is becoming a concern in some nursery settings. Not native to this area, it may arrive with nursery liners. It is a fall germinating winter annual, and a prolific seed producer. A native of the Soviet / Asian continent, it entered this country in the late 1920 s, most likely in small grain seed. Blue mustard germinates in the late fall; produces a rosette that has deeply lobed leaves, similar to that of a dandelion. Leaves are alternate, oblong in shape with a small petiole on the lower stem leaves. Upper stem leaves are sessile. Leaves that are produced on the flowering stem are coarsely toothed with wavy margins. It has a shallow taproot, and grows to about eighteen inches in total height. It will grow in a wide range of moisture and soil fertility conditions. The flowers have four petals and are blue to purple in color. Viable seed will be produced within ten days of the flowers opening. Control of this weed is important. It is considered invasive in certain states, but not in Maryland. The best time for post emergent control of blue mustard is in late winter to early spring when growth resumes. Control methods Photos: Chuck Schuster, UME should be used before mid-april at the very latest. In open settings, a 2, 4D product will work very well. Cultivation prior to the production of flowers is also useful. Dicamba as a selective post emergent is also labeled and works well. Pre emergent control can include Surflan (oryzalin) and Snapshot (trifluralin and Isoxaben) products, but need to be applied in late summer. Clopyralid (Lontrel) has been shown to have effect on this weed and can be used over the top in nursery settings. Use caution, as it will create some plant damage. Casoron (dichlobenil) has been shown in some areas to be effective and can be used in the nursery setting. In the non selective areas, gramoxone is a good contact defoliant, and glyphosate products will also work. When using glyphosate products, do not allow product to come into contact with exposed roots, suckers or trunks and stems. An area of blue mustard in bloom 7
Plant of the Week, Ginny Rosenkranz Phlox subulata, moss pinks, are native evergreen groundcovers that have thin pale green leaves in the winter that brighten up to a medium green in the summer. The plant expands and carpets the ground especially if they are planted in a full sun site with welldrained soil. Moss pinks are not picky about the soil ph, thriving in both mildly acidic and alkaline soil. Once established, the plants are very drought tolerant and slightly salt tolerant, making them a good candidate for sidewalk and driveway plantings. Moss pinks bloom for almost 4 weeks in the cool spring weather, less if the spring season heats up. Candy Stripe is an eye catching Phlox subulata with fragrant pure white flowers striped with bright pink down the center and darker pink near the center. Like Phlox subulata Candy Stripe all other Phlox subulata, Candy Stripe grows in USDA planting Photo: Ginny Rosenkranz, UME zone 3-10 and is susceptible to spider mites, rabbits, root and stem rot, powdery mildew, impatiens necrotic spot viruses and anthracnose. Plant Phenology: What is in bloom PLANT PLANT STAGE (Bud with color, LOCATION First bloom, Full bloom, First leaf) Acer rubrum First bloom Columbia (March 24) Camelia japonica First bloom Salisbury (April 3) Chaenomeles speciosa First bloom Salisbury (April 3) Cornus mas (cornelian cherry) First bloom Ellicott City (March 28) Corylopsis spicata Bud with color Silver Run (April 1) Daphne odora Marginata First bloom Silver Run (April 1) Dirca palustris (Eastern leatherwood) Bud with color Silver Run (April 1) Forsythia Full bloom Salisbury (April 3) Heleborus Phedar strain First bloom Silver Run (April 1) Lamium purpureum (purple deadnettle) First bloom Ellicott City (April 1) Osmanthus americanus Bud with color Silver Run (April 1) Phlox stolonifera First bloom Columbia (March 31) Pyrus calleryana Bradford First bloom Salisbury (April 3) Sarcoccoca orientalis First bloom Silver Run (April 1) Degree Days (As of April 4) Baltimore, MD (BWI) 8 College Park 31 Dulles Airport 19 Frostburg, MD 14 Martinsburg, WV 12 National Arboretum 31 Reagan National 31 Salisbury 47 To check degree day (DD) accumulations in your local area go to: http://www.weather.com/outdoors/agriculture/growing-degree-days/usmd0100 8
Operator Certification for Writing Nursery Nutrient Management Plans April 17th, 2013 Wye Research and Education Center 124 Wye Narrows Road, Queenstown, MD 21658 July 10th, 2013 Central Maryland Research and Education Center 11975-A Homewood Road, Ellicott City, MD 21042 Nursery Operator Certification for writing nursery nutrient management plans will be offered in two separate programs to accommodate growing season schedules. These training programs will assist you in writing a nutrient management plan for your nursery or greenhouse operation. You must write a nursery nutrient management plan if you use fertilizers and you gross over $2500 per year in sales. With this certification, you will be able to sign-off and submit your own plan. Each program consists of a Training Day and an Exam/Signoff Day. The Training Day will consist of learning the plan-writing process. After the Training Day you will have about 4 weeks, during which time you will study the Nursery Nutrient Management Training Manual and develop your plan. The Exam/Signoff Day will be for taking the exam and going over your newly developed plan. The process is relatively simple for small (or low-risk) operations, so if your operation size is less than 5 acres, we would strongly encourage you to think about becoming a certified operator. If your operation is larger than 5 acres, we would still encourage you to become a certified operator, even though the nutrient management process may be a little more complicated. Drs. John Lea-Cox and Andrew Ristvey will be happy to help you write your water and nutrient management plan. The first Training Day will be April 17th, 2013 at Wye Research and Education Center. We have scheduled the Exam/Signoff Day for May 15th at Maryland Department of Agriculture in Annapolis, MD. After passing the exam, you will be able to sign off on your plan and submit it. The second program s Training Day will be July 10th, 2013 at Central Maryland Research and Education Center just outside Ellicott City. We will schedule an Exam/Signoff Day for this program on the 10th of July. To express your interest in taking this training, please contact Mike Webster, Maryland Department of Agriculture at (410) 841-5957. Call Andrew Ristvey (410) 827-8056 x113 for directions to Wye Research and Education Center and the Central Maryland Research and Education Center. 9
Commercial Horticulture Industry Contact for Help With Plant Problems Diseases: Karen Rane: rane@umd.edu, 301-405-1611 Go to www.plantclinic.umd.edu to find out how and where to submit suspected disease samples to her lab. Insects: Stanton Gill: sgill@umd.edu, 410-868-9400 (cell) or 301-596-9413 (office) Paula Shrewsbury: pshrewsb@umd.edu, 301-405-7664 Brian Clark: bpclark@umd.edu, 301-868-8780 (Brian covers Prince George s County) Weeds: Chuck Schuster: cfs@umd.edu, 301-590-2807 Soil Substrates Plant Fertility: Andrew Ristvey: aristvey@umd.edu, 410-827-8056 Horticulture: Ginny Rosenkranz: rosnkrnz@umd.edu, 410-749-6141 ext 106 (Wicomico, Worcester and Somerset counties) For questions from homeowners and master gardeners, contact the Home and Garden Information Center, http://hgic.umd.edu or 800-342-2507, or your local Extension office. Upcoming Programs Brown Marmorated Stink Bug Conference April 10, 2013 Location: Carroll Community College, Westminster, MD Contact: Suzanne Klick, 301-596-9413 or sklick@umd.edu MNLA Nursery Field Day June 20, 2013 Location: Waverly Farm, Adamstown, MD Contact: MNLA, 410-823-8684 CONTRIBUTORS: Stanton Gill Extension Specialist sgill@umd.edu Paula Shrewsbury Extension Specialist pshrewsb@umd.edu Karen Rane Plant Pathologist rane@umd.edu Chuck Schuster Extension Educator cfs@umd.edu Ginny Rosenkranz Extension Educator rosnkrnz@umd.edu David Clement Plant Pathologist hgic.umd.edu Andrew Ristvey Extension Specialist aristvey@umd.edu Brian Clark Extension Educator bpclark@umd.edu 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.