for Arborists, Landscape Managers & Nursery Managers

Commercial Horticulture August 25, 2017Coordinator 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 AssistantDisease 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 (Extension Specialist, Wye Research & Education Center)Design, Layout and Editing: Suzanne Klick (Technician, CMREC)

In This Issue...

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

TPM/IPM Weekly Report

- Pollinator program- Saddleback caterpillars- Barberry webworm- Bagworms- Giant silk moth- Dogwood sawfly- Pear trellis rust

Beneficial of the WeekWeed of the WeekPlant of the WeekDegree DaysAnnouncements

Pest Predictive Calendar

IPMnetIntegrated Pest Management for

Commercial Horticulture

extension.umd.edu/ipm

Pollinator ProgramBy: Stanton Gill

Last week, I traveled down to Raleigh, North Carolina to meet with Bayer Company to go over current and future research efforts. During my visit, I had a chance to visit their bee lab in Raleigh. The bee team at Bayer has set up a program called Feed a Bee. The objective is to increase the food for honey bees and other pollinators across the United States by planting more flowers and increasing the diverse forage and habitat for the pollinators to thrive. They are looking for collaboration with individuals and organizations. You can visit Feedabee.com and click on impacts to find out how to apply for a grant to help with this effort.

Mountain mint (Pycnanthemum muticum) attracts many pollinators such as honey bees (above) and digger wasps (below)

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Stinging CaterpillarBy: Stanton Gill

This week I received an email from David Titman. His wife, Trish Steinhilber, and he were picking aronia fruit in Howard County. Trish was stung on the hand and arm. She was stung four times, but she could not find a flying insect. They finally noticed a bright green caterpillar feeding on the aronia foliage. They described it in the email as the caterpillar from hell.

It is the saddleback caterpillar, one of the several stinging caterpillars we have active on foliage in Maryland in August. Every year, we receive calls and emails about this stinging caterpillar. It is one of the most photographed caterpillars we receive pictures of at this time of year. Saddleback caterpillars, Acharia stimulea, belongs to a family called the slug caterpillars, Limacodidae. The bright green color on the dorsal side (upside) of the caterpillar is very eye catching. The oval-shaped brown patch encircled by white catches many people’s eye. For some reason, many people feel they have to touch this oval shape on the back. Bad mistake - be ready to be stung.

It has a pair of fleshy horns at either end. These horns and most of the rest of the body bear urticating hairs that secrete an irritating venom. The spines or hairs causes a painful, swollen rash. The best thing to do is watch out and avoid contact with the caterpillar while it is feeding in late August through early September. Control is really not necessary. It is a good opportunity to get a few photos of an interesting caterpillar.

Barberry webworms tie together leaves and shoot tipsPhoto: Steve Shaffer, Premium Lawn and Landscape

Keep an eye out for saddleback caterpillars which have stinging hairsPhoto: David Titman

Barberry WebwormSteve Shaffer, Premium Lawn and Landscape, found barberry webworm on August 23 in Midland VA. Look for the barberry webworm caterpillar in webbed cases covered with fass and leaves. It is a dark caterpillar with many small, white spots. Japanese barberry, one of its host plants, is invasive in Maryland woodlands and forests.

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Polyphemus moths overwinter in the pupal stagePhoto: Jean Scott

Giant Silk MothJean Scott found a polyphemous moth (one of the giant silk moths) this week. The large, bright green caterpillar of this moth feeds on a variety of woody trees and shrubs, but is not found in high numbers to be a problem.

BagwormsSteve Clancy, Country Springs Landscaping, found bagworms defoliating Thuja ‘Green Giant’. We have had some growers state that Thuja ‘Green Giant’ is not bothered by bagworms. This is obviously not so.

Bagworms are heavily infesting Thuga ‘Green Giant’ trees and causing significant damagePhotos: Steve Clancy, Country Springs Landscaping

Dogwood SawflyElaine Menegon, Good’s Tree and Lawn Care, is reporting that they are finding dogwood sawflies on red twig dogwoods in Hershey, PA. Dogwood sawfly will eat all but the midrib of the leaf. These sawflies overwinter in the last instar stage. After the second molt, the bodies of the larvae become covered with a white powder-like material to mimic bird droppings which helps to protect them from their enemies. At their final molt they have a spotted pattern to camouflage them as they crawl over leaf litter. It is fairly late in the season so the damage does not really impact the health of the tree. There is only one generation per year. Control: Options include Conserve, synthetic pyrethroids, and carbaryl.

As dogwood sawflies molt, their coloring and patterns change. The spotted pattern in the last instar helps camouflage them in the leaf litter where they pupate.

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Beneficial of the WeekBy: Paula Shrewsbury, University of Maryland

Long-legged flies (Diptera: Dolichopodidae)

We often see these small (~ ¼”) metallic long-legged flies zipping around our woody and flowering ornamental plants. Dolichopodid flies are very diverse with over 6,600 named species worldwide, and about 1,300 in North America. It does not seem like they are really doing much else but flying around. However, these beautiful little flies are actually predators. The adults of these “true flies” are often metallic green, blue or copper-colored. As true flies they have only 1 pair of wings and a pair of structures referred to as halteres where the second pair of wings would be on other insects. Halteres help flies with balance when they are flying. Long-legged flies are abundant in many managed and natural habitats, especially near swamps, streams, and in woodlands and meadows.

The legless larvae, which are maggets, are whitish and cylindrical. Larvae are found in varied habitats such as water, mud, decaying wood and grass stems. Little is known about the feeding habits of larvae but some are believed to be predaceous, others are leaf miners in grass stems. I have only been fortunate enough to actually see an adult long-legged fly feeding on prey a few times, once feeding on an azalea lace bug adult, the other time the prey was beyond recognition. Adults are known to feed on an assortment of small insects. There are reports of dolichopodid adults feeding on other flies, hoppers, Collembola, mites, thrips, dragon fly eggs, termites, bark lice, beetle larvae, and small caterpillars. Some dolichopodids have been seen feeding on honeydew, and a few species are known to feed on nectar from flowers. In addition to being beautiful (for a fly anyway) they also contribute to biological control in our managed ecosystems, even if we don’t see them eating other insects very often.

Note the characteristic long legs, metallic coloration, and single pair of wings of this adult long-legged fly. Photo: P. Shrewsbury, UMD

Pear Trellis RustBy: David Clement,UME

Marie Rojas, IPM Scout, is still seeing pear trellis rust infection this week. She found it on Pyrus calleryana ‘Blake’s Pride’. Pear trellis rust symptoms are very visible now on pear trees. This disease is caused by the rust fungus, Gymnosporangium sabinae, and has a complex life cycle between several species of juniper (Juniperus sp.) and ornamental (Pyrus calleryana) and orchard pears (Pyrus communis). Leaf spots on pear turn bright reddish orange by mid-summer. By late summer, brown, blister-like swellings form on the lower leaf surface just beneath the leaf spots. These spores are blown by wind to susceptible juniper species from late summer through fall where they cause infections on young juniper shoots.

Pear trellis rust infects both landscape and orchard pearsPhoto: David Clement, UME-HGIC

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Weed of the WeekBy: Chuck Schuster, University of Maryland Extension

Broomsedge, Andropogon virginicus, is found in nursery, landscape and low maintenance turf settings. Broomsedge is a clump forming perennial that is found in the mid Atlantic area. This weed is often not noticed until the mature reddish brown broom-like leaves appear later in the season. The leaf blades are keeled or folded, one eighth to one quarter inch wide and up to twenty four inches in length. Hairs are present near the leaf base. The sheath has long hairs on the overlapping margin. The flower is a panicle on the upper portion of the stem. This panicle will not be noticeable until the spikelets start to emerge and open. As the plant matures, the sheaths change color to a reddish brown. Broomsedge has a fibrous root system with very short rhizomes. Broomsedge prefers a lower pH, but once established will survive in a wide pH range. Broomsedge may also have an allelopathic effect to prevent other plants from being competitive with it.

Control of broomsedge is often obtained with appropriate nutrient fertility management. In areas where no plant growth is desired, under trees in a nursery, landscape areas, sethoxydim, (Vantage) can be used in many landscape and nursery settings. Nonselective translocated herbicides also work well, but caution needs to be used when considering use of these products as damage to nursery and landscape trees and shrubs is being noted.

Broomsedge is often not noticed until the mature reddish brown leaves appear later in the seasonPhoto: Chuck Schuster, UME

Plant of the WeekBy: Ginny Rosenkranz, University of Maryland Extension

Cedrus atlantica ‘Glauca Pendula’ or weeping blue atlas cedar can grow from 15 feet to 20 feet tall and wide or wider and makes a beautiful and dramatic living sculpture when it is planted as an accent piece in full sun with loamy, moist but well drained soils. The growth habit of the tree is upright, then pendulous or weeping and cascading in many directions if the plant is not supported. The ultimate size can be increased by training the central leader to its full height and then allow it to cascade. Plants can be trained as an espalier in a formal setting, but they do best when allowed to cascade like a waterfall. Winter hardy in USDA zones 6-9, weeping blue atlas cedar is tolerant of high humidity and summer heat. Once established, the plants are very drought tolerant. The evergreen ½ inch needles are a soft silvery blue-green and are held in whorled clusters along the stems, helping to create the waterfall effect. Plants are very slow growing, expanding only about 1 to 1 ½ feet per year. Pests include bagworms, scale, Deodar weevil, scale, tip blight, and root rot. Spring migrating sap suckers can be attracted to the tree to drill parallel lines in the bark.

The pendulous growth habit of Cedrus atlantica ‘Glauca Pendua’ makes it a good choice for a specimen plant in the landscapePhoto: Ginny Rosenkranz, UME

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Degree Days (As of August 23)Annapolis Naval Academy (KNAK) 3231 Baltimore, MD (KBWI) 3022 College Park (KCGS) 2976 Dulles Airport (KIAD) 3033Ellicott City (E247) 2922 Fairfax, VA (D4092) 3250Frederick (KFDK) 2983 Greater Cumberland Reg (KCBE) 2784 Gaithersburg (KGAI) 2894 Martinsburg, WV (C1672) 2824Natl Arboretum.Reagan Natl (KDCA) 3565 Rockville (C2057) 3333 Salisbury/Ocean City (KSBY) 3083 St. Mary’s City (St. Inigoes, MD-KNUI) 3320 Westminster (KDMW) 3165

Important Note: We are now using the Online Phenology and Degree-Day Models site. Use the following information to calculate GDD for your site: Select your location from the mapModel Category: All models Select Degree-day calculatorThresholds in: Fahrenheit F Lower: 50 Upper: 95Calculation type: simple average/growing dds Start: Jan 1

PLANT PLANT STAGE (Bud with color, First bloom, Full bloom, First leaf)

LOCATION

Allium tuberosum (garlic chives) First flower Ellicott City (August 24)Helianthus microcephalus First flower Columbia (August 23)

Phenology

Cut Flower Field Day/Tour

We worked with the Maryland Cut Flower Growers Associaton and the Association of Specialty Cut Flowers to set up a three farm visit (Honeybee Flower Farm, Smokey Cat Lavender Farm, and Seaberry Farm) for September 12, 2017. This year, we will be on the Eastern Shore of Maryland visiting some of the outstanding small to large cut flower operations. See the brochure for details. To register using a credit card, go to:http://2017cutflowertour.eventbrite.com

PGMS DC Branch Meeting Pope Farm NurseryProgram: Tour of Pope FarmSeptember 7, 2017Gaithersburg, MDFor information: http://pgms.org/pgms-branches/dis-trict-of-columbia-branch/

Top Native Plants for the Mid-Atlantic RegionPresenter: Holly ShimizuOctober 11, 2017Location: Johns Hopkisn University, Rockville, MDRegistration Information

Trees Matter SymposiumNovember 1, 2017Location: Silver Spring Civic Center, Silver Spring, MD

December Pest Management ConferenceDecember 15, 2017Location: Howard Community College, Columbia, MD

MANTSJanuary 10-12, 2018Location: Baltimore Convention Center

Advanced IPM Short CourseJanuary 8 - 11, 2018Location: University of Maryland, College Park, MD Contact: Kiley Gilbert, 301-405-3911, kgilber4@umd.edu http://landscapeipmphc.weebly.com/

FALCAN Pest Management ConferenceJanuary 19, 2018Location: Frederick Community College, Frederick, MD

Biological Control ConferenceFebruary 1, 2018 Location: Carroll Community College, Westminster, MD

Eastern Shore Pest Management ConferenceFebruary 7, 2018Location: TBD

The information given herein is supplied with the understanding that no discrimination is intended and no endorsement by University of Maryland Extension is implied.

CONTRIBUTORS:

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.

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.

Stanton GillExtension Specialist

sgill@umd.edu410-868-9400 (cell)

Paula Shrewsbury Extension Specialistpshrewsb@umd.edu

Ginny RosenkranzExtension Educatorrosnkrnz@umd.edu

Chuck SchusterExtension Educator

cfs@umd.edu

Karen Rane Plant Pathologistrane@umd.edu

Andrew RistveyExtension Specialistaristvey@umd.edu

David ClementPlant Pathologist

clement@umd.edu

Nancy HardingFaculty Research

Assistant

Courses Taught by Chuck Schuster and Stanton Gill at Montgomery College

LNTP 190 Pesticide Use & Safety 2 semester hours (Class ends on Oct. 16)Prepare for the pesticide application certification exam through a thorough understanding of the principles of pest control, including pesticide labeling, regulations and proper handling.Wednesday 6:00 - 9:30 p.m. CRN 23220 Instructor: Chuck Schuster

LNTP 215 Pest Management*, ** 3 semester hoursHone your pest management skills with Stanton Gill. Explore the identification of key pests, their life cycles and control methods, with emphasis on integrated pest management strategies.Thursday, 6:00 - 9:30 p.m. CRN 23226, CRN 23228 Lab Instructor: Stanton Gill

For further information about the program or courses, contact Stephen Dubik (240) 567-7803 steve.dubik@montgomerycollege.edu