for Arborists, Landscape Managers & Nursery Managers

Commercial Horticulture July 21, 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

- A new sunflower- Crapemyrtle aphids- Mosquito control?- Fall webworms- Powdery mildew- White prunicola scale- Catalpa sphinx moth caterpillar- A caterpillar on boxwood (not in US)- Cicada killers- Brown patch in turf

Beneficial of the WeekWeed of the WeekPlant of the WeekPhenologyDegree DaysAnnouncements

Pest Predictive Calendar

IPMnetIntegrated Pest Management for

Commercial Horticulture

extension.umd.edu/ipm

A New Interesting and Long Flowering SunflowerBy: Stanton Gill

This week, I was at the Cultivate 17 conference in Columbus, Ohio. Syngenta was showing off its new sunflower called Sunfinity. The plants were loaded with blooms. They claim it will continue to flower through the summer into the fall. If this is so, it would be an interesting small sunflower for customers with sunny landscapes. The display plants certainly looked good. I am trying to obtain seed to trial this plant out in the later part of the summer. It is a pollenless sunflower.

Sunfinity SunflowersTM have a long season of bloom

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Crapemyrtle AphidsBy: Stanton Gill

Crape myrtles are coming into their glory in July and the crapemyrtle aphid is having a heyday. Check your customers’ crape myrtles this week and see if you find the distinct looking aphids. Many times you will find winged stages (alates) along with non winged forms. Two good control options are Endeavour and Altus. Both are stylet blockers and relatively easy on pollinators and beneficial organisms.

Crapemyrtle aphids produce both non winged and winged forms throughout the season

Bug Zappers – Made Popular?By: Stanton Gill

The Zika virus problem is rising up again in South America and the press is picking up on the mosquito issue and how people should control them. Proctor and Gamble is releasing Zevo, an indoor trap for insects, including mosquitoes, gnats and moths. You plug it in like the electric odor devices that were so popular a couple of years ago. It emits a combination of UV and blue light that attracts insects. They are hung up on a sticky cartridges. They sell for under $15 and replacement cartridges are just under $6/piece. The cartridge is supposed to last at least 45 days, and you can replace it. It is attractive looking from the outside and the blue light it emits is rather pleasing. I am sure it will be a big hit, but not sure how many actual mosquitoes it will catch, especially inside the typical house where people keep doors and windows shut.

Fall WebwormsMarie Rojas, IPM Scout, is reporting that second generation fall webworms are now hatching out and beginning to feed in their silken nests on Tilia tomentosa ‘Sterling’ in Frederick County this week. These webworms feed on a wide host range of deciduous trees. Look for webbing on the tips of branches. Caterpillars feed within the “tent” which they enlarge as they feed and grow. Control: There are numerous predators and parasitoids that attack and kill fall webworm. If possible, prune out webbed terminals. Bacillus thuringiensis (Bt), horticultural oil, or insecticidal soap can be used for early instars. Contact is difficult because caterpillars are inside the webbed terminals. Confirm or Conserve are also options for control. Second generation activity of fall webworm will continue

through late summer

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White Prunicola ScaleBy; Stanton Gill

I received a sample of white prunicola scale on Thursday and second gneration crawlers were active. They should still be active this week, but we are moving into the time of year when they become settled 1st insatrs. Distance and Talus still work on them. There is a third generation of crawlers that will be active in early September.

A braconid wasp has parasitized this catalpa sphinx moth caterpillar; there are wasp pupal cases on itPhoto: Brandon Rushing, B. Rushing Lawn and Landscaping

Check infested plants to see if the salmon colored crawlers of white prunicola scale are still active

Powdery Mildew

Marie Rojas, IPM Scout, is reporting powdery mildew on oaks, Magnolia ‘Ann’, and Physocarpus ‘Center Glow’ in Frederick County. A film of water on foliage is needed for powdery mildew infection. Several products are labeled for control of powdery mildew on ornamentals in the landscape, including sterol inhibitors such as Banner Maxx and Eagle, QoI products like Heritage and Insignia, chlorothalonil (Daconil and others) and combination products like Pageant and Spectro 90. Fungicides are most effective in managing powdery mildew when used preventively. Always follow all label instructions, as rates, timing and crops listed will differ between products.

High humidity creates favorable conditions for powdery mildew infectionPhoto: Marie Rojas, IPM Scout

Catalpa Sphinx Moth Caterpillar (Catalpaworm)Brandon Rushing, B. Rushing Lawn and Landscaping, found a catalpa sphinx moth caterpillar that has been parasitized by a braconid wasp. There are several generations a year of catalpa sphinx moth caterpillars which can be found from June through early fall. Coloration varies from yellow to mostly black. Look for parastic wasps which help keep these caterpillar populations in check. Bt can be used for small larvae and other labelled insecticides can be used for larger caterpillars if needed.

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The Poor Boxwood PlantBy: Stanton Gill

I received an email from Alan Jones. He was traveling in Europe and said the talk of the town was the boxwood moth. He sent me an email to see if we had this pest in the US. On checking – not so far. The boxwood pest he was inquiring about is actually called (in Europe) the box tree moth. Its Latin name is Cydalima perspectalis and is in the family Crambidae. It is from Asia (Japan, China, Taiwan, Korea, and Russian Far East) and showed up in Germany in 2006. It then showed up in Switzerland and the Netherlands in 2007. It was found in Great Britain and France in 2008, and in 2012 it was introduced from Italy to Sochi with the planting stock of Buxus sempervirens. In 2013, it was found new to Denmark at several sites in the island of Sjaelland.

How Does It Damage Boxwood? The larvae feed on the leaves and shoots of Buxus species. The young larvae only eat the upper part of the leaf. The leaves are not destroyed completely but appear as “pealed” or shredded almost completely. These pealed leaves eventually die. Older larvae are the most damaging: they massively and completely eat the leaves, sometimes leaving a thin part at the contour and center of the leaf, however. Green ball-shape frass (caterpillar poop) can usually be seen on host plants. Let’s hope this pest does not make it to the U.S. anytime soon.

Cicada KillersWe have been getting reports of cicada killer activity throughout the month. Only female wasps are capable of stinging and cicada killers are not aggressive to humans. Adult cicada killers feed on nectar. Female cicada killers hunt for cicadas to take back to their burrows to feed to their young. Males can be found in large numbers when defending their territory.

Paula Shrewsbury, UMD, has more details on these predators in the June 30, 2017 IPM report. Discourage females from building nests by keeping the soil moist and improving the density of the turf and soil quality.

Brown Patch DiseaseMark Schlossberg, ProLawn Plus, Inc., is finding brown patch disease in lawns now. The hot, humid weather with evening thunderstorms has been very favorable for this disease. Brown patch starts as circular spots and spreads out to turn whole areas brown. You may see grass blades with foliar mycelium in the early morning if it is warm and humid in the early stages of the infection process. Look for brown margins with tan centers on infected foliage. Although lawns turn brown they do recoup when the weather cools down. To reduce the incidence of brown patch in tall fescue lawns avoid applying nitrogen in the spring. Nitrogen promotes soft, succulent growth that is more susceptible to infection by the brown patch fungal pathogen, Rhizoctonia solani. Look for mycelium from the brown patch fungus

in the morningPhoto: Mark Schlossberg, ProLawn Plus, Inc.

Female cicada killers take cicadas back to their burrows to feed their young

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Beneficial of the WeekBy: Paula Shrewsbury, University of Maryland

Parasitic wasps can penetrate the bags of bagworms!In your travels and monitoring of plants you are likely seeing active bagworms, Thyridopteryx ephemeraeformis (common bagworm, Lepidoptera: Psychidae), and their feeding damage on a diversity of evergreen and even deciduous plants. Optimal suppression of bagworms (IPM) includes mechanical tactics whenever feasible. This would include hand removal of bags which contain the caterpillars. Be sure to drop the picked off bags into a bucket of soapy water or squish them. Do not just drop the bags to the ground or the caterpillars will crawl back (dragging their bags with them) onto the tree, or put them in a plastic bag which they are known to chew their way out of to escape (personal experience!). If there are only a few plants and the bags are within reach then hand removal is a feasible and cost effective approach. The next management approach on the list would be the use of a product containing the bacteria Bacillus thuringiensis (Bt) to target the early instars. It is too late for that approach now. Selection of other chemical controls used now when caterpillars are later instars should be selected by taking into account their impact on natural enemies. Products such as Conserve (spinosad), Acelepryn (chlorantraniliprole), or Confirm (tebufenozide) should have reduced impact on natural enemies and provide good control of bagworms (thorough coverage of the foliage is important; read the labels!). The reason for this selection is that there are a number of natural enemies that attack bagworm caterpillars and we want to conserve as many of them as possible.

There are over 11 species of parasitic wasps that attack bagworms. Today I will discuss a parasitoid that is commonly found attacking bagworms, Itoplectis conquisitor (Hymenoptera: Ichneumonidae). Just the name sounds powerful! Itoplectis is indigenous to North America and a generalist parasitoid known to attack and parasitize the pupal stage of many Lepidoptera (butterflies and moths) hosts, including bagworms. It has also recorded to attack some beetle and sawfly species. Itoplectis is considered to be a solitary endoparasitoid. This means the wasp larva develops within its host and only 1 wasp emerges from any given single host. Studies in Ontario found 5 generations per year to occur. Female Itoplectis insert their ovipositor through the protective bag of pre-pupal and pupal bagworms (and other host insects) and then inject an egg into the insect. The egg hatches and the wasp larva consumes the bagworm pupae. A study in northern VA by UMD researchers identified about 10 species of parasitic wasps attacking the pupal stage of bagworms. Itoplectis conquisitor accounted for 58% of bagworm parasitism. The researchers found that smaller “bags” were parasitized at a greater rate than larger “bags”. Since male bagworms are usually smaller than female, rates of parasitism of males was higher than females. Interestingly, the study determined that the ovipositor of Itoplectis was not long enough to penetrate the bags and reach the pupae of larger bags. Itoplectis combined with a suite of other parasitoids and predators can have a suppressing impact on bagworms. In another study, researchers demonstrated that the edition of flowering plant species to landscapes can increase parasitism by I. conquisitor, in addition to other parasitoids and predators. So, as usual, remember plant diversity and floral resources are important toward the conservation of natural enemies and their biological control services.

For more information and photos on bagworm biology and management go to: http://entnemdept.ufl.edu/creatures/ or OSU Extension Bagworm (includes a photo of a female wasp on the outside of the bag).

An adult female Itoplectis conquisitor, an ichneumon wasp that is a generalist parasitoid, attacks a wide range of Lepidoptera speciesPhoto: Gerald J. Lenhard, Louisiana State University, Bugwood.org

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Weed of the WeekBy: Chuck Schuster, University of Maryland

During the last two weeks, this weed has been noticed a great deal. Sticking up above low growing annuals and perennials, it is unsightly. Eastern black nightshade, Solanum nigrum, is an annual weed which has an erect growth pattern. This plant grows primarily east of the Rocky Mountains. It is found in many settings including nurseries, landscapes, and some agronomic crops. This summer annual grows to about 14 inches and has a tap root with diffuse fibrous root hairs extending form the taproot.

The leaves of this weed are simple, alternate, and usually ovate. The leaf margin may be entire and will most often be slightly pubescent (hairy). The stem below the cotyledons will have slight hairs that can be purple to maroon. The upper surface of the leaves will be green, and the lower surface will be maroon or purple. It will germinate from seed and can be distinguished from bitter nightshade as bitter nightshade will spread from creeping stems that root at the nodes. The fruit of eastern black nightshade is a berry which can measure from 5-14 mm in diameter and will be purplish black in color at maturity and green when immature. Each berry can contain from 50-100 seeds.

Control of this weed can be obtained through the use of mulch to prevent germination. Many pre-emergent broadleaf products designed for the landscape, simazine based products, and post emergent applications of glyphosate products will control this plant. Always use caution with any herbicide as they do have the potential of harming desired species of plants.

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

Populus tremuloides, quaking aspen or American aspen, has the largest area where it grows as a native deciduous tree, from New Mexico to Alaska, from the Pacific Northwest to the Northeast. Quaking aspen is dioecious, meaning that each tree is either a male or a female tree, and they grow from a huge underground root system creating clones. In the west, quaking aspen is one of the first to regrow after forest fires, and the root system that produces the clones can live for a very long time. The oldest clone is from Minnesota and is estimated to be over 8,000 years old. They thrive from USDA zone 1-6, growing best in full sun with acidic, moist, well drained soils. If grown in hot summer areas they become very susceptible to many diseases and insect pests. Quaking aspen grows in a tall, slender silhouette with a narrow rounded crown, growing 20-50 feet tall and 20-30 feet wide. Like many in the poplar family, quaking aspen can grow up to 24 inches a year. The

Eastern black nightshade has a taproot with fibrous root hairsPhoto: Howard F. Schwartz, Colorado State University, Bugwood.org

Each Eastern black nightshade berry can contain 50-100 seedsPhoto: Phil Westra, Colorado State University, Bugwood.org

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Degree Days (As of July 19)Annapolis Naval Academy (KNAK) 2240 Baltimore, MD (KBWI) 2112 College Park (KCGS) 2084 Dulles Airport (KIAD) 2139Ellicott City (E247) 2041 Fairfax, VA (D4092) 2310Frederick (KFDK) 2084 Greater Cumberland Reg (KCBE) 1958 Gaithersburg (KGAI) 2032 Martinsburg, WV (C1672) 1959Natl Arboretum.Reagan Natl (KDCA) 2541 Rockville (C2057) 2263 Salisbury/Ocean City (KSBY) 2156 St. Mary’s City (St. Inigoes, MD-KNUI) 2366 Westminster (KDMW) 22217

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

bark when young is a creamy white to light green, which matures to a bright chalk white with black streaks and warty patches. The slightly rounded leaves are a bright, glossy dark green from spring to late summer when they turn a clear golden yellow. The leaves also provide movement and music in the landscape as they flutter with each tiny breeze, due to the flattened petioles. In its habitat, quaking aspen provides food for rabbits, deer, elk and beaver as well as many birds and butterflies. Like all fast growing plants, quaking aspen is prone to many diseases including dieback, leaf spot, rust, powdery mildew and cankers, while insect pests include caterpillars, borers, aphids and scale. However, in the right setting quaking aspen can become a beautiful specimen or a lovely grove of trees.

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

LOCATION

Eutrochium fistulosum (Joe pye weed) Buds with color Ellicott City (July 21)Hibiscus moscheutos (perennial hibiscus) First flower Ellicott City (July 19)

Phenology

A quaking aspen root system produces clones that live for a very long timePhotos: Ginny Rosenkranz, UME

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

Green Industry Summer PicnicAugust 19, 2017Location: Just This Side of Paradise Farm, Woodbine, MD

Cut Flower Tour - Eastern ShoreSeptember 12, 2017

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