for Arborists, Landscape Managers & Nursery Managers

Commercial Horticulture June 21, 2013Coordinator 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)

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

- Wet weather and weeds- Japanese beetles- Spittlebugs- Fire blight- Brown marmorated stink bugs- Bagworms- Scale updates- Slug sawfly- Powdery mildew - Tip dieback- Fall webworm- Saddleback caterpillar moth- Main peachtree borer- Lace bugs- Gypsy moth- Oak leaf skeletonizer

Weed of the WeekPlant of the WeekDegree DaysPhenologyAnnouncements

A New Address for IPMnet

Integrated Pest Management for

Commercial Horticulture

extension.umd.edu/ipm

Wet Weather – Lots of WeedsNursery managers are reporting an abundance of weed growth this spring. The heavy downpours leached many pre-emergents out of the soil profile and are helping grow a bumper crop of weeds in 2013. Two perennial vine weeds that are doing especially well this spring are Oriental bittersweet and poison ivy. Birds that feed on the seeds of these vines often land in nursery trees and shrubs and spread the seed in their fecal droppings just below the nursery plants.

Oriental bittersweet is susceptible to glyphosate applications, but it is best to get the plants when they are small. Poison ivy can be burned back with glyphosate, but it often grows back after an application. Garlon directed onto the poison ivy is effective, but it is best applied with a wick applicator to avoid it contacting other plants or being picked up by roots of the desired plants growing near the poison ivy.

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Japanese BeetlesMark Quesenberry, Damascus Enterprises, Inc., found his first Japanese beetles for the year in the Gaithersburg/Damascus area on June 19. We are receiving reports from a few others who so far have only seen one or two on a few plants.

SpittlebugsGinny Rosenkranz, UME, and Debby Smith-Fiola, IPM Scout, are reporting that native pine spittlebugs, Anphrophora parellela, are active on pine and leyland cypress. The twolined spittlebug is another species found in this area on herbaceous and woody plants. The nymphs feed on plant sap from under frothy, spittle-like foam which protects them from predators, parasites and dry weather. If you examine the spittle closely, you will find the nymphs within.Control: Usually not necessary for this pest.

Fire BlightThe wet weather is continuing to spread fire blight on apples, pears and some shadbush plants. When we have dry periods, prune out the damaged wood, cutting 12 – 18” below any discolored or cankered areas on the branches.

Recentlly hatched BMSB nymphsPhoto: Marty Heidel, Arader Tree Serivce

Brown Marmorated Stink Bugs (BMSB)This week, we received several e-mails reporting brown marmorated stink bug egg masses being found. The photos of the egg masses are helping several people recognize this life stage of BMSB. Jason Sersen found an egg mass and newly hatched nymphs on a hosta in a landscape in Baltimore County. We have had reports of egg masses on ornamental and fruit bearing cherry trees. They also like to lay eggs on peach and nectarine tree foliage. Your customers may find the nymphs feeding on their fruit this week. If your customers have vegetable gardens have them examine the foliage of pepper, eggplants, and sweet corn. Brown marmorated stink bugs prefer to lay eggs on these vegetable plants. If you detect an egg mass, remove the foliage with the egg mass before they hatch. The nymphs are fairly easy to kill with directed sprays of insecticidal soap. When they are small and susceptible is the time to treat these bugs.

Spittlebug on pinePhoto: Ginny Rosekranz, UME

BagwormsMarie Rojas, IPM Scout, is reporting that bagworms are just hatching out and blowing around on a variety of conifers in Beallsville and Adamstown this week. Debby Smith-Fiola, IPM Scout, is finding second instars in Keedysville (990 degree days at this site).Control: Applications of Bt or Spinosad (Coserve) should give good control of early instars.

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Scale Updates

White prunicola scale (WPS, armored scale): Monitoring WPS populations on Tuesday June 18 in Laytonsville found 3rd instar females without eggs and emerged adult males. We will continue to monitor for the 2nd generation of crawlers which should be in July. The degree days according to weatherchannel.com in Laytonsville on June 18 were 945 DD. Japanese maple scale (JMS, armored scale): Monitoring JMS on cherry trees in Laytonsville, MD on June 18 found 3rd instar females with eggs and a high number of crawlers and settled crawlers. We are at the best point for control applications for Japanese maple scale since crawlers and settled first instars are present for the majority of the population. We suggest using either Distance or Talus insect growth regulators since they are effective and have the least negative impact on beneficial organisms. In 2012, we conducted a trial using Dinotefuran as a soil drench and it gave good control of Japanese maple scale.

Juniper scale: There are no more live adults or crawlers. All crawlers have settled now and first instars are secreting their covers.

Cottony maple scale: Marie Rojas, IPM Scout, found crawlers of cottony maple scale on Rose of Sharon in a landscape in Laytonsville. Gary Wisniewski, Scientific Plant Service, found this scale on red maple in Baltimore on June 15. Look for the yellow crawlers on the undersides of leaves.Control: Talus or Distance with 1% oil. This scale can be controlled with soil applications of dinotefuran (Safari, Transtect), imidacloprid (Merit - landscape, Marathon - nursery), or thiamethoxam (Flagship).

Indian wax scale: Monitoring Indian wax scale on holly in Columbia on June 17 found that this scale is now in the crawler stage at 854 degree days. Pyriproxyfen (Distance) or buprofezin (Talus) applied when crawlers are present works well.

Cryptomeria scale: Marie Rojas found cryptomeria scale immatures on Korean firs in Montgomery and Frederick Counties.

Cottony Camellia/Taxus Scale: Jean Scott, Rainbow Tree Care, reported this scale on plants on the Eastern Shore on June 14. Jon Cholwek, Bonifant Tree Service, is reporting seeing a lot of cottony camellia/taxus scale on holly trees and shrubs. Jon noted that the trees and shrubs with the highest scale populations are the ones that have been repeatedly sheared with gas hedge shears several times a year and that this creates an ideal environment for scale insects. Jon recommends that these trees and shrubs be pocket pruned to allow light and air inside the shrubs and trees. In the May 7, 2010 IPM report, Stanton Gill noted if you tightly shear holly, there is no way that you will be able to penetrate these plants with chemical sprays to contact the pest. Control can be applied now. Use either Distance or Talus or a soil drench of imidacloprid or dinoterfuran is effective.

Japanese maple scale: purple crawler on the left and later stages on the right

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Slug Sawfly on Nyssa sylvaticaMarie Rojas, IPM Scout, found a cool slug sawfly on Nyssa sylvatica ‘Wildfire’. Marie found a reference from 1971 of a sawfly, Caliroa nyssae, on Nyssa, but we have not confirmed the identification of the sawfly found. Spinosad products can be used for control.

Note: The black tupelo leafminer is a caterpillar that has been a problem on Nyssa sylvatica in previous years. It causes blotch mines in the leaves. Damage is usually seen starting in July.

Powdery MildewMarie Rojas, IPM Scouts, is reporting that powdery mildew is showing up on various cultivars of Cornus florida and on a fullmoon maple in a landscape. Bright, sunny days and cool nights promote powdery mildew infection.

Tip DiebackMarie Rojas is noticing that on plants plants that suffered tip injury during that late cold snap that there is a LOT of tip dieback. She noted that Cercis canadensis and Picea orientalis ‘Gracillis’ are showing quite a bit of damage.

Fall WebwormWe are starting to receive regular reports of fall webworm activty. Marty Adams, Bartlett Tree Experts, found early instars on June 17 on sweetgum in Baltimore County and Hamamelis ‘Pallida’ in Carroll County. Grady Reed, Thrive, Inc., is also finding webbing on trees. Damian Varga, Scientific Plant Service, found fall webworm on sweetgum in Ellicott City. We have seen the caterpillars on various plants in Howard County including on black tupelo here at the research center. Fall webworm has a wide host plant range. The larvae feed within the webbing they produce.Control: Bt, horticultural oil or insecticidal soap for early instars or prune out webbed branches. There are many predators and parasites that help keep this pest below damaging levels.

Slug sawfly larvae infesting Nyssa sylvatica leavesPhoto: Marie Rojas, IPM Scout

Powdery mildew starting on maplePhoto: Marie Rojas, IPM Scout

Fall webworm infesting black tupelo

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Hawthorn lace bug on cotoneasterPhoto: Mark Schlossberg, ProLawn Plus, Inc.

Main Peachtree BorerWe continue to find adult main peachtree borers in our baited pheromone trap this week. Monitor cherry, peach, plum and cherry laurel for oozing at the base of the plants. This oozing is a good indicator of main peachtree borer activity. Protectant sprays of Permethrin (Astro) or Bifenthrin (Onyx) can be made to the trunks of susceptible plant material.

Saddleback Caterpillar MothOn Monday, we had an interesting little moth on our front door. It was the moth of the saddleback caterpillar. The moth has some of the green and brown color pattern as the caterpillar stage which is usually the stage people report finding. Remember, avoid touching the caterpillar when you find it since it has has stinging hairs. The saddlbeback caterpillar should be active in July and August.

Gypsy MothDamian Varga, Scientific Plant Service, reported finding gypsy moth larvae on blue spruce in Syksville on June 14.

Lace BugsMark Schlossbergy, ProLawn Plus, Inc., is finding hawthorn lace bug on cotoneaster this week. Hawthorn lace bug also feeds on pyracantha. Examine newer foliage for stippling damage on upper leaf surface, dark colored frass spots and active lace bugs on underside of leaves.Control options include: acetamiprid (TriStar), acephate (Orthene) or a foliar treatment of dinotefuran (Safari, Transtect).

Oak Leaf SkeletonizerDamian Varga, Scientific Plant Service, reported finding oak leaf skeletonizer larvae feeding on white oak in Annapolis on June 18.Control: Not necessary, but Bt or Conserve would work well.

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Plant of the Week, Ginny RosenkranzSyringa reticulata, Japanese tree lilac, is a compact small tree growing 20-30 feet tall and 15-20 feet wide with beautiful, creamy, white, fragrant lilac blooms from May to June. Each flower is combined with others to form a 6-12 inch panicle creating large candles of color in the tree when in bloom. These fragrant flowers attract hummingbirds, butterflies and other pollinators, but are often ignored by browsing deer. If the flowers are pruned after blooming, no seeds will be created and better flowering will be enjoyed the next year. The dark, deciduous, green leaves are arranged in an opposite fashion on the reddish brown bark and are very powdery mildew, scale and borer resistant compared to the common lilac bush. Since it is a small tree, it is ideal for small courtyard gardens, street trees planted under power lines, as a boundary marker or as a specimen. There are a number of cultivars including ‘Ivory Silk’ which has very deep green leaves and flowers heavily, ‘Chantilly Lace’ with yellow to cream margins on the green foliage and ‘Summer Snow’, again a heavy bloomer. They are cold hardy from USDA zone 3-7 and like many flowering plants do best in full sun with moist well drained soils. Once established, the plant is moderately tolerant of drought conditions and has fair salt tolerance. Even in the winter the branching pattern of the tree adds interest to the outdoor gardens. Insect pests include lilac borer, especially in drought stressed trees, lilac leafminer and scale. Disease pests include Verticillium wilt, Phytophthora blight and frost injury to early expanding leaves.

DodderPhoto: VT Weed ID Guide

Syringa reticulata ‘Ivory Lace’ in bloom at Waverly Farm, Adamstown, MD, during the June 20th MNLA Field Day

Weed of the Week, Chuck SchusterDodder, Cuscuta spp., is an unusual weed often found in the landscape. Unlike most other plants, this plant is a parasitic vine that is able to derive its nutrients from other plants. The seedling can only survive a few days away from a host plant, but a mature dodder plant can survive for several days when removed from the host. It does not have the ability to penetrate tree bark, but will attach itself to leaves of trees and shrubs. Dodder vines continually attach to the host plant as it grows and will move to new host plants that are in close proximity which will allow the plant to form a dense mat of yellow to reddish-brown vining stems that twin in a counterclockwise direction. The plant has small, almost unnoticeable, leaves and will produce a white to pink cluster of flowers. The seeds are extremely hard and require some form of scarification before germinating in soils once temperatures reach 60 °F. Seed is often spread by human contact, plant movement and sometimes water.

Control of dodder starts with proper identification. The dodder plant may have roots for a few days after germination until it can find a host plant. The use of mechanical removal will require several attempts as seed can germinate over a long period of time. Post emergent herbicides are not suggested as they generally will also damage the host plant. Pre-emergent herbicides can be effective if applied in the early spring when known infestations have been noted. Trifluralin (Treflan) does provide good control. Watch the site for several years as seeds will remain viable for long periods of time.

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Degree Days (As of June 20)Baltimore, MD (BWI) 1092 College Park 1334Dulles Airport 1152 Frostburg, MD 646 Martinsburg, WV 1038 National Arboretum 1334 Reagan National 1334 Salisbury 1275

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 for various pests use the Weather.com web site, a base temperature of 50 °F, a start date of January 1st, and the date of monitoring as the end date.

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

LOCATION

Agastache foeniculum Full bloom Ellicott City (June 21)Asclepias tuberosa First bloom Ellicott City (June 17)

Plant Phenology: What is in bloom

A New Address for the IPMnet WebsiteUniversity of Maryland Extension made changes to its website this spring. Now, the IPMnet site is at a new address which is http://extension.umd.edu/ipm. The IPM alerts and conference information will be posted at this new location. The old address of ipmnet.umd.edu will be up for a little longer, but new information will not be added to it.

MDA Pesticide Container Recycling Program

MDA is once again conducting a pesticide recycling program. For a list of dates and locations of collection sites, go to

http://mda.maryland.gov/plants-pests/Documents/recycle.pdf

Stanton GillExtension Specialist

sgill@umd.edu

Paula Shrewsbury Extension Specialistpshrewsb@umd.edu

Ginny RosenkranzExtension Educatorrosnkrnz@umd.edu

Chuck SchusterExtension Educator

cfs@umd.edu

Karen Rane Plant Pathologistrane@umd.edu

Brian Clark Extension Educator bpclark@umd.edu

Andrew RistveyExtension Specialistaristvey@umd.edu

David ClementPlant Pathologist

hgic.umd.edu

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.

Upcoming Programs

The Maryland Christmas Tree Association (MCTA) Summer Christmas Tree MeetingJune 22, 2013Location: Jarrettsville Nurseries, 1121 Holy Cross Road, Street, Md 21154. Agenda and registration: gavertreefarm@aol.com.

Nutrient Management Plan Writing – Nursery and Greenhouse ProductionJuly 10, 2013, 9 a.m. to 3:30 p.m.Location: CMREC, 11975 Homewood Road, Ellicott City, Contact: Andrew Ristvey, aristvey@umd.edu, 410-827-8056 x113

IPM Pest WalkJuly 11, 2013Stanton Gill, David Clement and Ginny Rosenkranz will lead a pest walk at the Salisbury University campus. The program starts at noon with lunch at Fratelli’s Restaurant. Cost: $25.00Contact Ginny Rosenkranz, 401-749-6141, ext 106, for registration details

Flower Trial Field Day - Penn State ExtensionJuly 25, 2013Location: Manheim, PAhttp://agsci.psu.edu/flower-trial

Summer Cut Flower TourAugust 6, 2013

Eastern Shore: Salisbury and FederalsburgFor the brochure: extension.umd.edu/ipm