for Arborists, Landscape Managers & Nursery Managers

Commercial Horticulture October 21, 2016Coordinator 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. Please

include location.

TPM/IPM Weekly Report

- Hercules beetles- Brown marmorated stink bugs- Velvet worms- Woolly apple aphids- Eggs in the fall

Beneficial of the WeekWeed of the WeekPlant of the WeekPhenologyDegree DaysAnnouncements

IPMnetIntegrated Pest Management for

Commercial Horticulture

extension.umd.edu/ipm

Big Beetles – Big Grubs!Stanton Gill

One of my students from the IPM and Entomology Class at Montgomery College brought in a container with the biggest white grubs you will see in Maryland. She also had two very large adult beetles, one male and one female, in the container. They are the larval and adult stages of the eastern hercules beetle, Dynastes tityus, which is the largest beetle in this part of the country. Adult eastern hercules beetles typically have green, gray, or tan elytra mottled with black spots. Adult male beetles have 2 large horns: 1 on the head and 1on the thorax. Adult females lack horns. The beetles and grubs were found in a rotting piece of firewood. You commonly find that the females will lay eggs in rotting tree stumps in the summer. The larvae overwinter and the adults emerge out in late summer to early fall. Adults are harmless to living plants. It one of the largest and most interesting beetles you will find in Maryland.

Hercules beetles are the largest beetles found in this area

Male

Female

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This predaceous velvet worm feeds on insects in soil and leaf litter

Pyracantha is one of the hosts of woolly apple aphidsPhoto: Ginny Rosenkranz, UME

Brown Marmorated Stink Bugs - Staging a Minor Comeback? Stanton Gill

Back in 2009 and 2010, homeowners were inundated with swarms of overwintering adult brown marmorated stink bugs. We saw feeding activity in nurseries, orchards, and vegetable production areas. They were driving everyone crazy. Fortunately, the populations crashed down in the following years until we barely saw any activity out of this beast. The weather, fall storms, feeding by birds, and increased predator and parasite activity all attributed to their massive decline in population numbers.

In the fall of 2016, the brown marmorated stink bugs are staging a small scale comeback. We are getting reports from Carroll County, Washington County and Northern Baltimore County of adults migrating into houses and other structures with the cool weather last week. Not in the numbers we saw back in 2009 – 2010, but they are still making their presence known. Once they are inside the easiest solution is to get out the shop vac or portable vacuum and suck the bugs up and dispose of them. So, BMSB have died down in numbers, but don’t count them as down and out quite yet.

Velvet WormsA few velvet worm larvae were found this week. The adults are soldier beetles that often visit goldenrod flowers late in the season feeding on nectar and pollen. The larvae feed on insect eggs, small caterpillars, fly larvae (maggots), other soft-bodied insects, and slugs and snails.

Paula Shrewsbury, UMD, covered velvet worms as the ‘Beneficial of the Week’ on September 25, 2014.

Woolly Apple AphidsGinny Rosenkranz, UME, found an infestation of woolly aphids on pyracantha this week. Common hosts include crabapple, alder, elm, mountain ash, hawthorne, serviceberry and pyracantha. Adults are reddish-purple and have a waxy covering. When monitoring, look for honeydew and sooty mold on trees. This aphid feeds on both roots and on new terminal growth which can cause the leaves to curl and form rosettes. Check to see if the aphids are dead since predators such as lady bird beetles, syrphid fly larvae and lacewing larvae feed on the aphids, leaving the waxy residue behind. There is also a parasitic wasp that feeds on these aphids. If control is warranted, horticultural oil and insecticidal soap can be used which have a reduced impact on beneficial insects if they are present.

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Look for barrel-shaped wheel bug eggs in clusters on woody plants

Eggs in the FallAt this time of year, as many insects and spiders are winding down their activity for the season, look for egg masses on plants and buildings at scouting sites.

An argiope spider laid eggs in this egg sac, right next to her web connected to our building

Praying mantids are laying egg masses at this time of year; look for eggs of the native Carolina mantid (left) and the introduced Chinese mantid (above)

2017 ADVANCED LANDSCAPE IPM PHC SHORT COURSE - JANUARY 3 – 6, 2017

We are pleased to announce the 2017 Advanced Landscape IPM PHC Short Course. This annual Short Course held in College Park, MD is a recertification short course for arborists, landscape supervisors, IPM monitors, advanced gardeners, and others responsible for urban plant management.

For further information and registration materials please click on the following link http://landscapeipmphc.weebly.com/ or contact Kiley Gilbert, IPM Short Course Coordinator, Phone: 301-405-3911, E-mail: kgilber4@umd.edu

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Beneficial of the WeekBy: Rebeccah Waterworth and Paula Shrewsbury

After writing the Beneficial of the Week on Sept. 30th (Maryland’s state insect, Baltimore checkerspot butterfly), we were curious about the identity of Virginia’s state insect. It is another butterfly species, the common Eastern tiger swallowtail, Papilio glaucus (Order Lepidoptera, Family Papilionidae). It was designated as the official insect of the Commonwealth in 1991 by the Virginia General Assembly.

These butterflies have two flight periods in this area, with the first in May. They overwinter as pupae (chrysalis) near the ground in protected, covered spaces. In fact, the last instar larvae (or caterpillars) are looking for pupation sites right now; there was a report of a tiger swallowtail caterpillar walking across a parking lot in the Oct. 7th issue of the IPM Weekly Report! These large butterflies (wingspan up to 6 ½ inches) emerge from their chrysalises in May and are common sights along roadside edges and within or near deciduous broadleaf forests. Larval host plants include sweetbay, tulip tree, and magnolia (Magnoliaceae), wild cherry, and ash. Adult females seek out any of these host trees and lay one large spherical egg at a time on leaves with an average of 120 eggs laid over her lifetime. Larvae hatch and develop, and by July, there is another flight of swallowtails during which time more eggs are laid. Caterpillars that hatched during this mid-summer period are the ones that are now preparing to pupate and overwinter.

Swallowtail butterflies, especially tiger swallowtails, are fascinating insects, both as larvae and as adults. During their first three instars (life stages), caterpillars mimic bird droppings! They openly rest on the upper surfaces of leaves, whereas many other caterpillars would only be found underneath to avoid predation by birds. No one wants to eat poop which allows these bird poop mimics to enjoy the sunshine on the top of leaves! After the third instar, caterpillars develop a lovely green coloration. Prominent yellow eyespots (not real eyes) are also visible on the top of the thorax. One of my favorite things to do when I encounter a swallowtail caterpillar is to “provoke” it until it everts its osmeterium, an orange, fleshy, horn-shaped organ that is found immediately behind the head. With a quick glance, this organ looks like a forked tongue of a snake. When an unsuspecting bird approaches a swallowtail caterpillar, the caterpillar quickly pushes the osmeterium out, and the bird is startled away because the eyespots and the osmeterium give the caterpillar the appearance of a small snake. Osmeterium not only look bad to a potential predator; the chemicals that are emitted smell horrendous and repel small predators, such as ants, wasps, small spiders, and mantids. These chemicals include isobutyric acid, a compound that smells like rancid butter. I should mention that all larval stages have osmeterium, not just older caterpillars.

An Eastern tiger swallowtail (yellow morph) nectaring on butterfly bush (Buddleia sp). Swallowtails get their name from the characteristic tail-like projection on the hindwings. Photo by: R. Waterworth, UMD

An Eastern tiger swallowtail (black morph)Photo by: Allen Bridgman, South Carolina Department of Natural Resources, Bugwood.org

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Life as an adult is really interesting, too. Tiger swallowtails have an enormous geographic range and are found everywhere south of the Canadian border to the Gulf of Mexico and from the Atlantic Ocean to just east of the Rocky Mountains. Male tiger swallowtail butterflies are always yellow with black bands. However, female tiger swallowtail butterflies are dimorphic which means that females can either be the “usual” yellow morph (dominant morph seen in our area) or a black morph, which is more common in the southern areas (Virginia and southward). We see both color morphs in MD. In the southern parts of its range, the distribution of tiger swallowtails overlaps with the distribution of pipevine swallowtails, Battus philenor (a black and blue species). Pipevine swallowtails are unpalatable to predators. Scientists have determined that the black morph of female tiger swallowtails is a mimic of the pipevine swallowtail. Predators that have experienced the bad taste of a big black butterfly (pipevine swallowtails) are unlikely to eat any additional black butterflies, even if they are edible black tiger swallowtails. This offers the tiger swallowtail a little protection while flying around in plain sight!

Next summer I plan to check leaves of cherry and magnolia trees more closely. I will not let bird poop, small snakes, or the smell of rancid butter deter me!

A late instar Eastern tiger swallowtail caterpillar. Note the protruding osmeterium (orange horns) behind the head and the prominent yellow eyespots. This larva is mimicking a snake! Larvae can reach 2.2 inches in length. Photo by: Howard Ensign Evans, Colorado State University, Bugwood.org

An early instar Eastern tiger swallowtail caterpillar mimicking bird poopPhoto by: Jerry A. Payne, USDA Agricultural Research Service, Bugwood.org

Weed of the WeekBy: Chuck Schuster

Chicory, Cichorium intybus, is a perennial plant that some consider a weed, and others utilize it in coffee and in some foods. It can be found in turfgrass and landscapes as well as pastures throughout the United States. This weed can be misidentified as dandelion, but when flowering is easy to tell the difference. The root system is a taproot, and is brown in color; the initial plant is a rosette similar to the dandelion. The stems are branched and appear later in the season. Blue to purple flowers help in the proper identification of this plant. The flowers are produced in clusters of one to three with each flower being about one inch in diameter. Flowers are squared on the tips and toothed. The leaves of chicory are initially produced to form a basal rosette making it appear similar to the dandelion. Leaves produced later will be on a flowering stems. All leaves are alternate with stiff hairs on both upper and lower surfaces. Leaves have toothed margins, are

With the recent warm weather, chicory is still actively growingPhoto: Chuck Schuster, UME

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lobed and are not opposite like dandelion. Rosette leaves are coarsely toothed, three to eight inches in length and three inches wide. Flowering stem leaves are much smaller. The flower stems are very different from dandelion; the stem of chicory produces leaves, is stiffer and will have leaf bases surround the flowering stems. Chicory prefers sites with low fertility, and will survive extreme droughts.

Control of chicory can be obtained in the landscape and turf through fertility management. Chicory prefers poor soils. Mowing will not eliminate it, but prevents seed formation. This is a perennial weed so other methods will need to be considered. Glyphosate products only provide fair control, and the later in the season the less success will be gained. In turf, post emergent broadleaf herbicides, including triclopyr, 2,4D and dicamba work very well. Late season applications have been less than successful. With the recent warm weather the plant is still actively growing.

Plant of the WeekBy: Ginny Rosenkranz

Iris germanica ‘Summer Olympics’ is an early spring blooming, clump forming herbaceous perennial that also re-blooms in the fall. It was named to honor the Olympic games held in Los Angeles, CA in 1984 and has become an excellent addition to herbaceous gardens ever since. The standards or the upright flower petals are a translucent yellow with ruffles at the edge and the falls or cascading flower petals are also ruffled around the edge, yellow with a white throat and bright yellow beard. Each flower stalk holds 8 - 10 blooms that are slightly fragrant. The sword straight, evergreen leaves spike up to over a foot tall and the flowers stalks grow up to 2 ½ feet tall. Cold hardy from USDA zone 3-9, ‘Summer Olympics’ prefers full sun for best flowering and will grow in moist, very well drained soils with a pH of 6.1-7.8. Once established, ‘Summer Olympics’ is very drought tolerant. After flowering, the stalk should be trimmed off to promote new growth. Rhizomes should be cleaned of dead foliage and plant debris in the fall to prevent overwintering borers and mulch should be kept off the iris crown to prevent rot. They are resistant to deer damage, but will be damaged by slugs and snails. Iris rhizome rot and grey mold are potential diseases.

Iris germanica ‘Summer Olympics’ produces bright yellow flowers in spring and fallPhoto: Ginny Rosenkranz, UME

Degree Days (As of October 12)Annapolis Naval Academy (KNAK) 4287 Baltimore, MD (KBWI) 4056 College Park (KCGS) 3926 Dulles Airport (KIAD) 4095Ellicott City (E3247) 3964 Fairfax, VA (D4092) 4325Frederick (KFDK) 3786 Greater Cumberland Reg (KCBE) 3857 Gaithersburg (KGAI) 3751 Martinsburg, WV (C1672) 3835Natl Arboretum.Reagan Natl (KDCA) 4721 Rockville (C2057) 4440 Salisbury/Ocean City (KSBY) 4074 St. Mary’s City (St. Inigoes, MD-KNUI) 4425 Westminster (KDMW) 4070 Important Note: We are now using the Online Phenology and Degree-Day Models site.

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

Commercial Horticulture Conferences

New Location for 2016 December 2016 ConferenceHoward Community College in Columbia for December 16, 2016. Look for the schedule in late October.

Advanced Landscape Plant IPM PHC Short CourseJanuary 3rd to January 6thWebsite: landscapeipmphc.weebly.comFor registration information vist our website or contact:Kiley Gilbert, University of Maryland, Dept of EntomologyTel: 301-405-3911, Monday-Friday 8-4:30Email: kgilber4@umd.edu