TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers Commercial Horticulture October 10, 2014 In This Issue... - Brown marmorated stink bugs - Neonicotinoid update - Woolly bear caterpillar - Elm bark beetle Beneficial of the Week Plant of the Week Degree Days Announcements 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) and Nancy Harding, Faculty Research Assistant 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) IPMnet Integrated Pest Management for Commercial Horticulture extension.umd.edu/ipm 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 Brown Marmorated Stink Bug (BMSB) Update By: Stanton Gill Last week I requested emails on brown marmorated stink bug adult activity in Maryland. Thanks to all who responded to our request. We had reports of activity in Fallston (Anne Arundel County), Hampstead (Carroll County), Adamstown (Frederick County), Silver Spring (Montgomery County), Reisterstown (Baltimore County) and Keedysville (Washington County). We received no reported activity on the Eastern Shore or in Southern Maryland. When the cold weather came on Saturday and Sunday the adult BMSB activity dropped to almost nothing, but A wheel bug feeds on a BMSB adult. Photo: Charlie Dalton, Dalton Ventures, Inc. as it warmed up on Monday we started finding adults active on our building at the Central Maryland Research and Education Center in Clarksville. They are present, but fortunately not at the levels we saw 3 years ago. (See the Beneficial of the Week for more information on wheel bugs)
College of Agriculture and Natural Resources Open House October 11, 2014 (10 a.m. to 3 p.m.) Location: Central Maryland Research and Education Center - Clarksville Facility 4240 Folly Quarter Road, Ellicott City, MD 21042 Find out more at http://agnr.umd.edu/openhouse Come to our Open House at the farm and learn how our Academic, Research, and Extension programs benefit you. See the horses, cows, calves, and turtles... participate in birdwatching...see the beautiful butterflies...watch chicks hatch out of their eggs... check out the backyard poultry... take a hay wagon farm tour... visit the educational and interactive displays and exhibits on everything from nutrition to rural enterprise development... participate in the numerous hands-on activities... purchase some food from one of the student organization food tents... talk with an AGNR representative... and get your plant questions answered by a Master Gardener Update on Neonicotinoids By: Stanton Gill While attending entomology/pathology meetings last week in North Carolina, we discussed neonicotinoid use on ornamentals. Dave Smitley, Michigan State University, had conducted trials in 2014 to measure the impact on bumble bees. Dave had his students treat potted annual plants in flower with imidacloprid. The plants were placed in netted outdoor cages and treated with the neonicotinoid, imidacloprid. Commercially available bumble bee colonies were placed in the netted tents. The different colonies were placed in tents treated with imidacloprid the same day. Honey bee colonies were also placed at varying intervals between treatment such as 1, 3, 7, 14 day after treatment. Untreated tents with the same plants were used as a control. After exposure he retrieved the bumble bee colonies. Their state apiculturist suggested counting the bumble bees and marking their thorax with a colored pen so they did not double count the bumble bees. It was suggested to handle the bees in a darkened room with only red light since supposedly the bees cannot see red light. Dave said after being stung 6 times in the room under the red light he was ready to quit the trial. The apiculturist suggested he try counting them in a room lit with red light and with cold temperatures such as a walk-in cooler that was cooled to 38 F. This worked and they did not get stung. They compared the number of healthy bumble bees in each colony in the different treated intervals to the untreated control colony numbers. What he found is if plants were sprayed with imidacloprid and there was least a one week interval from time of spraying to time the bumble bees were exposed then there appeared to be not impact on the bumble bees. He suggests that a good safety margin would be to not apply foliar sprays of imidacloprid at least 2 weeks before the plants go outside. Woolly Bear Caterpillar Fall is a time of year when we often receive reports of woolly bear caterpillar sightings as they cross sidewalks, parking lots and driveways. There are two generations a year, and the caterpillars overwinter under leaf litter in the last instar. Brian Scheck, Maxalea, Inc., found one on October 9 in Baltimore County. The amount of orange banding is not an indication of how the winter will be. The amount of orange increases with each molt so older caterillars have a wider band of orange. It feeds on a variety of low growing herbaceous and woody plants. The wide orange band on this woolly bear caterpillar indicates it is a late instar. Photo: Brian Scheck, Maxalea, Inc. 2
Elm Bark Beetle Norm Brady asked an interesting question about the American bark beetle and Dutch elm disease that it vectors. We asked Bob Rabagalia to comment on the bark beetle and the relationship with DED. Comments from Bob Rabaglia, Acting Deputy Director, Forest Health Protection USDA Forest Service: You are correct that DED came to the US on infected elm wood but the European elm bark beetle was here about 30 years before the fungus arrived. The beetle was first found in the US in the early 1900s in Massachusetts (and probably was here sometime before that). The fungus that causes DED was introduced into the Cleveland area in the 1930s on elm logs. So, the beetle does not need the fungus and in fact in its native range it was not necessarily a vector. The fungus came to Europe from Asia (post WWI) and to the US from Europe. The fact that the European elm bark beetle feeds in the twig-crotches of healthy elms makes it an efficient vector (it attacks the bole of the tree to breed after the tree is dying). In Europe the larger elm bark beetle (same genus) is also a vector and has the same feeding habit. In the US the native beetle feeds on branches, has a 1 generation per year life cycle (the European has up to 3 per year), has a more limited distribution and lower populations which all make it a less efficient vector. As far as the galleries are concerned I think the direction (across the grain or with it) is a function of the condition of the tree when the beetle species attacks. As I said, the European beetle was not always associated with the fungus and after it feeds on twigs (some think they do this for maturation or maybe just to get energy and water) it then normally attacks dying, stressed trees that have little resistance. The native beetle feeds in and attacks branches that may offer more resistance. By cutting across the grain they sever the vessels and reduce the response by the tree. That s why the galleries of the emerald ash borer zig zag across the grain too. The European beetle can go with the grain since the trees they attack for breeding are usually much weaker. That s the way I understand this anyway, and if you look at bark beetles across the different hosts and species of beetles you will see many different gallery types and orientations. Beneficial of the Week By: Paula Shrewsbury These heavily armored predators are fierce. We (Shrewsbury and Raupp labs, UMD) are conducting a study to determine the extent of damage that brown marmorated stink bugs cause when feeding on the bark of ornamental trees. In this study, we wrap cages made of screening around tree trunks and infest the cages with stink bugs. Last week when a research assistant, Chris, went out to check the cages she found predatory wheel bugs on the outside of the screen cages. But what really made it interesting was that it was a mating pair of wheel bugs, and not only were they mating but the female kept poking her long sharp mouthpart through the holes in the screen trying to pierce into a stink bug inside the cage. I guess you could call that multi-tasking! Wheel bugs, Arilus cristatus, are true bugs (Hemiptera: Heteroptera) in the family Reduviidae which include a group of predators known as assassin bugs. Assassin bugs are very important predators of a diverse array of pest insects in our ornamental systems. This particular assassin bug gets its common name, wheel bug, because of the spoke bearing, wheel-like structure on the pronotum (section behind the head) of the adults. They are large bugs with adults reaching 1-1.5. Immature wheel bugs are smaller, their abdomens seem to curl up at the back end and often have a red/orange coloration of their abdomen. They have long thin antennae and legs with black and orange bands. Most importantly both adults and nymphs have a long, dangerous looking proboscis (mouthpart) that they use to suck the life out of their prey - literally. Wheel bug adults and immatures are generalist predators that feed on insects such as caterpillars, plant hoppers, sawfly larvae, aphids, Japanese and other beetles, and stink bugs. The wheel bug approaches its prey, quickly grabs it with its front legs, and then impales the insect with its beak. Through its beak the wheel bug injects 3
digestive enzymes which liquefy the body tissues of the prey making it possible for the predator to suck up its food. There is one generation per year of wheel bugs. At this time of year you will see mostly adults. The female wheel bugs will soon be laying clusters of 10-40 eggs on the bark of trees. The eggs hatch the following spring. Nymphs and then adults are active through most of the growing season adding to the complex of generalist predators that help to suppress herbivore insect populations. Once the female wheel bug has feasted on a stink bug meal it will then lay eggs in a mass on the trunk of trees which is how it overwinters. Photo: P. Shrewsbury, UMD The predatory wheel bug adult with its large sucking mouth part stuck into a brown marmorated stink bug adult resulting in its death. Photo: M. Raupp, UMD This wheel bug is standing over a recently laid egg mass; the black and red nymphs will hatch next spring. Photo: Dave Keane, Howard County Recreation and Parks 4
Plant of the Week, Ginny Rosenkranz Hydrangea paniculata Fire Light is a new Proven Winners ColorChoice flowering shrub. It is a hardy hydrangea, growing from USDA zones 3-9. Like many hydrangea, Fire Light blooms on new wood so the plants should be pruned either in late fall or early spring to ensure lots of new foliage and flowers. Fire Light grows 4-6 feet tall and wide with beautiful flowers that can produce blooms 12-16 inches tall on strong upright red stems that resist flopping or drooping similar to the upright blooms of Two views of Hydrangea paniculata Fire Light TM Photos: Ginny Rosenkranz, UME Limelight. The flowers are the main attraction. The florets start out pure white and shift to shades of pink, rose and red so that at any one time all colors are showing on the plant. Fire Light starts early, blooming in mid-summer and continues to bloom into the coolness of autumn. The faded blooms last through the winter. Organically rich, moist, well drained soils are preferred and the flowers grow true to color in many soil phs. Hydrangea paniculata Fire Light grows well in full sun to part shade. The plants can be used in the landscape in foundation plantings, in shrub borders, at the back of perennial borders and even in a cutting garden as the flowers are excellent as fresh or dried flowers. Pests include bacterial wilt, leaf spot, rust, mildew, aphids and mite. Degree Days (As of October 9) 2014 2013 2012 2014 2013 2012 Baltimore, MD (BWI) 3517 3730 4218 Dulles Airport 3341 3705 4071 Frostburg, MD 2218 2313 2591 Martinsburg, WV 3353 3414 3763 National Arboretum 4341 4285 4781 Reagan National 4341 4285 4781 Salisbury 3908 4080 4385 St. Mary s City 3695 3857 4451 To check degree day (DD) accumulations in your local area go to: http://www.weather.com/outdoors/agriculture/growing-degree-days/usmd0100. Note: degree days reported in this newsletter use a base temperature of 50 F, a start date of January 1st, and the date of monitoring as the end date. 5
Upcoming Conferences: Advanced Landscape Plant IPM PHC Short Course January 5-8, 2015 For registration information contact: Avis Koeiman Department of Entomology 4112 Plant Sciences Building University of Maryland College Park, MD 20742 Tel: 301-405-3913 Email: akoeiman@umd.edu The 2014 to 2015 Conference Listing is posted on-line. Schedules and registration information will be added as it becomes available. Trees Matter Symposium: Trees and the Built Environment November 5, 2014 Silver Spring Civic Center, Great Hall montgomeryparks.org/trees 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 David Clement Plant Pathologist hgic.umd.edu Andrew Ristvey Extension Specialist aristvey@umd.edu Ginny Rosenkranz Extension Educator rosnkrnz@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.