for Arborists, Landscape Managers & Nursery Managers

Commercial Horticulture July 19, 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

- Heat and humidity- Cut flower tour- Lawn fertilizer law manual- Japanese beetles- Brown marmorated stink bugs- Scale update- Southern blight- Gypsy moth- Mimosa webworm- Ambrosia beetles- Squash bugs- Yellowing of Kousa dogwood foliage- Caterpillars and moths- Bagworm- Bald cypress twig gall

Beneficial of the WeekWeed of the WeekPlant of the WeekDegree DaysPhenologyAnnouncements

A New Address for IPMnet

Integrated Pest Management for

Commercial Horticulture

extension.umd.edu/ipm

The Heat and Humidity Are Almost Unbearable This Week!The high temperatures this week should stress plant material and any plants with compromised root systems will likely start to show scorching or dieback in the weeks following this heat. We have had several comments from turfgrass companies that most of the lawns in the area that are made up of fescue are heavily impacted by brown patch disease. The high moisture levels, high temperatures and humidity are making perfect conditions for the Rhizoctonia fungus that causes brown patch.

Cut Flower Tour - University of Maryland ExtensionAugust 6, 2013Locations: Long Season Statice Farm, Salisbury, MD, and Seaberry Farm, Federalsburg, MD

Our cut flower farm tour on August 6th offers the unique opportunity for current and potential cut flower growers to learn about new growing methods and unusual cultivars to help develop and diversify their own operation.

A brochure is available at https://www.extension.umd.edu/ipm/conferences

2

Japanese BeetlesLast year we predicted it would be a big Japanese beetle year. Several people are emailing in pictures of plant material covered with adult beetles. The beetles are hammering cherry trees, plum trees, roses, linden trees, grapes, blackberries, zinnias, sunflowers, hibiscus and crabapples. These plants are just some of the worst hit this season. One manager noted that they seem to start on dark leaf varieties first, and then fan out to green foliage plants. Back in 2003 and 2004, we had record amounts of summer rains. The egg and larval survival rate for Japanese beetles was excellent during this wet period. As a result during the seasons of 2004 – 2006, we had almost ridiculous numbers of adult Japanese beetles defoliating a wide range of plant material. Unfortunately, since the numbers are high in 2013 and we are having a wet period in July during egg laying period of Japanese beetles we will have an even bigger population of adult Japanese beetles in 2014. This will give you something to plan for in 2014. It should create a need for Japanese larval control in turfgrass late this summer. Many materials work on controlling adult Japanese beetles including pyrethoids such as permethrin and bifenthrin. Carbamates such as carbaryl give about 7-10 days of control. Acephate also gives fair control of Japanese beetles. They should give control for about 5 - 7 days, assuming we don’t get additional heavy rains like we had during the second week in July. Neem products will give repellency for 3 – 4 days at best.

Eggs, 1st instar and just molted 2nd instar of BMSB on sunflower

Lawn Fertilizer Law Manual - Now AvailableFrom Debby Freburger, MDA Nutrient Management Program: The following link provides information in a press release of today’s date that the Professional Lawn Care Manual is now available on our website:http://news.maryland.gov/mda/press-release/2013/06/25/mdas-professional-lawn-care-manual-now-available-online/

For those of you who would like to skip directly to the website of the manual follow this link: http://mda.maryland.gov/SiteAssets/Pages/fertilizer/MDAProLawnCareManual6.24.13.pdf

The requirement for certification is October, 2013; however, there are no examination dates set at this point in time. Please review the Urban Nutrient Management website for those updates as they occur. If you have further questions regarding the subject, please contact Dr. Jo Mercer at jo.mercer@maryland.gov; and/or our Urban Nutrient Management Specialist, Judy McGowan at judy.mcgowan@maryland.gov.

Brown Marmorated Stink Bug (BMSB) on Tropical HibiscusWe received a report from a garden center that the tropical hibiscus (Hibiscus rosa-sinensis) is serving as a major host plant for brown marmorated stink bugs (BMSB) on which to gather and lay eggs. There has been no injury noted so far, but we will continue to check them as the nymphs hatch. We did see feeding injury on hardy hibiscus in 2011 at CMREC. We would like to know if others are seeing BMSB gathering on tropical hibiscus in their garden center or nursery. Please let us know at sgill@umd.edu. Thanks.

3

Scale UpdateWhite prunicola scale (WPS, armored scale): Monitoring of WPS on Yoshino cherry trees this week in Laytonsville found, as we predicted last week, that the 2nd generation 1st instar CRAWLER population spiked (69%), with small populations of settled 1st instars (29%) and 3rd instar females with eggs (2%). On July 16, the Degree Days were 1708 DD.Monitoring: Check the degree day accumulations in your area, if they are close to 1708 DD, look for salmon colored crawlers on the trunk and branches of WPS infested plants. To assist in monitoring crawler activity you can apply tape (i.e. electrical or blue painters tape) with the sticky side out around the trunk/branch of the plant. The most common host plants to monitor are Prunus species, lilacs, and privets .Control: When crawlers are out, apply pyriproxyfen (Distance) or buprofezin (Talus) mixed with 0.5 - 1%

Japanese maple scale (JMS, armored scale): Monitoring JMS populations in Laytonsville on July 16 found many 2nd instars, some 3rd instars and 3rd and 4th instar males. We will continue to monitor for the second generation of crawlers. Degree days on July 16 in Laytonsville, MD were 1708 DD.

Ajuga plants infected with Southern blight fungusPhoto: Karen Rane, UME

Southern BlightThe recent hot and humid weather has been perfect for the development of Southern blight, a crown rot disease caused by the fungus Sclerotium rolfsii. Many herbaceous ornamentals such as hosta, ajuga peony and astilbe, are susceptible. The fungus produces white mycelial strands on infected plants, as well as small, round, seed-like sclerotia that change from white to tan to brown as they mature. These structures can survive in the soil for many years. As with most fungal diseases, sanitation is important in disease management. Closely examine new plants for sclerotia or white fungal growth at the crown/base of the stems, and do not purchase or install symptomatic plants. If the disease appears in a garden, remove and discard infected plants, as well as the soil around the plants, and avoid moving contaminated soil on tools or shoes. Mulches piled around plant stems can encourage Southern blight spread (the fungus can colonize the mulch material), so keep mulch away from the crown or base of susceptible plants. Some studies have shown that sclerotia do not survive being buried in soil at least 6 inches deep, so deep tillage in a garden may be helpful in some instances. Fungicides available to commercial applicators to help manage southern blight include azoxystrobin (Heritage), fludioxonil (Medallion), and tebuconazole (Torque). Check product labels for specific rates and application instructions.

Sclerotia (small round white “balls”) and mycelium of the Southern blight fungus on ajugaPhoto: Karen Rane, UME

4

Gypsy MothsMarty Adams, Bartlett Tree Experts, sent in photos of gypsy moths laying eggs on blue spruce in West Friendship on July 16.Control: Physically remove and destroy egg masses where possible.

Heavy infestation of gypsy mothsPhotos: Marty Adams, Bartlett Tree Experts

Mimosa WebwormDamian Varga, Scientific Plant Service, sent an email of a larva of the mimosa webworm, Homadaula anisocentra, which feeds primarily on the leaves of mimosa and honeylocust trees. It was unintentionally introduced from China into the United States during early 1940s. These caterpillars are from the first generation of the year. First generation adults appeared in early to late-June this year, and they may live for several weeks. Females laid eggs on the terminal leaves and small twigs as well as on webs from the previous year. Larvae hatched in early July and immediately began to feed on the lower surface of leaflets. Mature larvae from the first generation pupate in mid- to late July and the second generation of adults should appear in August. Second generation larvae are active during August and early September. Larvae from this generation may be so abundant that they web leaves throughout the entire crown of the tree causing it to look completely brown.

Watch to see if there is activity in your area. It is too late to apply anything for this generation, but monitor for the next generation. Spinosad or Bt applied when they first start feeding should give good control. Acelepyrn is a systemic for caterpillar control and should give excellent control. This caterpillars disfigures foliage, but it does not kill the tree.

Mimosa webworm caterpillarPhoto: Damian Varga, Plant Scientific Service

Ambrosia BeetlesMarty Adams, Bartlett Tree Experts, is reporting that the next generation of ambrosia beetles are producing frass tubes on yellowood in Marriottsville this week.

5

Yellowing Foliage of Kousa DogwoodsDave Clement, HGIC, received samples of Cornus kousa with yellowing foliage. No diseases, mites or insects were found. The only thing we can figure is that the excessive rains followed by high temperatures are stressing the plants resulting in yellowing foliage.

Squash bug adults

Squash bug eggsPhoto: Whitney Cranshaw, Colorado State University, Bugwood.org

Yellowing of foliage on Cornus kousa

Squash BugsMany of your customers may have vegetable gardens with squash, pumpkins, and cantaloupe growing in them. A bug they need to watch for in July is the squash bug. The adults are out and mating this week in central Maryland. The females lays a cluster of amber to brown colored eggs on the undersides of foliage of squash, pumpkins and cantaloupe. While all of the cucurbit crops can be attacked, it shows a preference for squashes and pumpkins. Avid gardeners should flip over their foliage and use a sharp knife to cut away the leaf tissue on which the egg mass is laid and destroy the eggs. It only takes about 7 - 10 days after eggs are laid before they hatch into nymphs. This insect can be very difficult to control when populations are allowed to build up. If you let them go, it will be death for the plants.

Squash bugs damage plants by removing sap and causing leaves to wilt and collapse. Young plants and infested leaves on older plants may be killed. More importantly, they are the vector of a newly recognized disease of cucurbit crops, Yellow Vine Decline. Melons, watermelon, and pumpkins are susceptible to this disease. The bacteria that causes this disease is injected into the plant while squash bugs feed with their piercing-sucking mouthparts. The disease results in yellowing, wilting and death of the plant. Early infection by the bacteria that causes the disease can result in severe yield loss, so it is very important to prevent squash bugs from feeding on young plants early in the season.

Control: Protectant sprays of Neem products will help protect susceptible plants. The customer will need to repeat the applications every 3 – 5 days to provide protection

6

Parasitized catalpa sphinx moth caterpillar

Caterpillars and MothsCatalpa Sphnix Moth Caterpillar: Norm Brady, Bartlett Tree Experts on the Eastern Shore, received a catalpa sphinx moth caterpillar that was identified by Jennifer Schlag who is in his office. It was feeding on Chatalpa tashkandensis which is a botanical hybrid of Chilopsis and Catalpa. Marty Adams, Bartlett Tree Experts, reported that catalpas were being defoliated by this caterpillar in Ellicott City this week.Control: Usually not necessary, but Bt can be used for small caterpillars. Check to see if parasitic wasps are attacking the larvae.

Orangestriped Oakworms: Bob Mead, Mead Tree Experts, found orangestriped oakworm that had just hatched and were still in clusters on Pin Oak in Montgomery County this week. Other common hosts include other oak species, chestnut, hazel, hickory and maple. Larvae feed in clusters and initially skeletonize leaves. Larger caterpillars are defoliators and only leave behind the leaf mid-rib.Control: If necessary, use Bt for small larvae. Synthetic insecticides are needed to control large caterpillars. Look for caterpillars that have been parasitized by wasps.

Giant Leopard Moth, Hypercompe scribonia: Bill Miller, The Azalea Works, sent in a photo of a giant leopard moth. The larvae of this moth are not considered a pest. There is a similar looking moth, called the leopard moth (Zeuzera pyrina) that can be a problem when the larvae bore into trees.

Pandorus Sphinx Moth: Gary Huntsberger, Greenkeeper, sent in a photo of the pandorus sphinx moth. The larvae feed on Ampelopsis, grape and Virginia creeper.

Hummingbird Clearwing Moth: These moths are active and nectaring heavily on the flowers of Monarda fistulosa that we have growing here at the research center. These moths look a lot like bumblebees and hover like hummingbirds.

Giant leopard mothPhoto: Bill Miller, The Azalea Works

Mid instar orangestriped oakworm

Pandorus sphinx mothPhoto: Gary Huntsberger, Greenkeeper

7

Baldcypress Twig GallMarty Adams, Bartlett Tree Experts, is finding the baldcypress twig gall midge on trees in Lutherville.There are two generations per year.Control: Usually not necessary. Timing of chemical controls is critical because applications need to be made before galls begin to form. Pruning can be done to reduce the number of galls present. There are several species of wasps that parasitize gall-forming insects and help reduce the number of galls formed.

BagwormBagworms continue to be active. Trisha Marty, Thrive, Inc., is finding bags that are about an inch long in Leesburg, VA this week. Sam Fisher, Woodacres Tree Specialists, reported bagworm on crapemyrtles.Control: Conserve, Orthene, Acelpryn, and Astro are options for control of bagworms.

Bagworm on crapemyrtlePhoto: Sam Fisher, Woodacres Tree Specialists

Beneficial of the Week, Paula ShrewsburyPredatory mites eat spider mitesRecent reports suggest an abundance of activity from two-spotted spider mites, Tetranychus urticae, which are herbivorous mites that feed on a wide range of deciduous trees, shrubs, and herbaceous and annual plants. Twospotted spider mites are active during the heat of the summer. We are there… it is hot! Two-spotted spider mites are commonly found on the underside of foliage, have a sucking type of mouthpart that removes chlorophyll from plant cells, and their feeding results in fine yellow stipples (spots) or stippling of the foliage. Fine webbing is also associated with spider mites. Several species of predatory mites are natural enemies of twospotted spider mites and other plant feeding mites and thrips. There are several families of predatory mites, but the most common predators of spider mites are in the family Phytoseiidae. Predatory mites have needle-like chelicerae (mouthparts) that they insert into spider mites or spider mite eggs to remove the fluids of their prey. Phytoseiid mites are about the same size as spider mites but their bodies are tear-drop or pear shaped. They tend to be a clear yellow to orange color (depending on species and sometimes prey item). Relative to plant feeding mites, phytoseiids have longer legs and run faster. Remember they must forage or hunt for their food. Predatory mites occur in nature and they can be purchased commercially and released (known as augmentation biological control). Most documented success with augmentative release of predatory mites has been in indoor environments such as green houses or conservatories. However, in outdoor environments naturally occurring predatory mites are believed to be very effective biological control agents in ornamental landscapes and nurseries. Most important to the success of naturally occurring predatory mites is the selection and use of pesticides that have minimal impact on these predators to help in the conservation and build-up of these natural enemies. Many pesticides in the Pyrethroid class are known to have long term detrimental impacts on predatory mite populations. Other miticides such as those on the “EPA reduced risk” list (ex. acequinocyl (Shuttle), bifenazate (Floramite), and others) or horticultural oil (follow label instructions) have been shown to have little impact on predatory mites. It may take a year or two of “wise” pesticide use to build up effective predatory mite populations. This practice will also help to conserve other natural enemies of spider mites such as the spider mite destroyer lady beetle or green lacewings.

To view a predatory mite feeding on a two-spotted spider mite, go to http://www.ipm.ucdavis.edu/PMG/M/I-AC-MOCC-AD.050.html

8

Small carpetgrassPhotos: Chuck Schuster, UME

Phlox paniculata ‘David’Photos: Ginny Rosenkranz, UME

Weed of the Week, Chuck SchusterSmall carpetgrass, Arthraxon hispidus, also known as joint-head grass, is an annual grass that can be found in turf and landscape settings in the eastern United States. Introduced from Japan and eastern Asia, some early reports show its earliest introduction was in the early 1970’s. This monocot can grow up to eighteen inches in height, produces an oval-shaped, pointed leaf that produces hairs where the leaf base encircles the sheath. Leaves are about two and one half inches in length, and three quarters of an inch in width, and produce a thin membranous ligule that is up to one eighth inch long. This plant produces a spike of flowers that will resemble fingers. The root system is fibrous, and the plant will root at nodes. Control of this weed in turf can be accomplished using products labeled for crabgrass pre emergent control (pendimethalin, dithopyr, prodiamine, oxadiazon). Mowing to prevent seed head production will reduce plant density in following years. Post emergent non selective herbicides work effectively in landscaped areas

Plant of the Week, Ginny RosenkranzPhlox paniculata, summer phlox, is a native herbaceous perennial that grows well in USDA zones 4-8 in most well drained soils. Full sun and excellent air circulation is necessary for both plant health and vigor. As powdery mildew is the main pest, watering must be accomplished by early morning to allow foliage to dry out. ‘David’ was the first cultivar to be fairly powdery mildew resistant, and both the fragrant flowers and the bright green foliage look good all summer long even in the muggy heat on the Eastern Shore. Both butterflies and humming birds visit a garden with blooming 3-4 foot tall summer phlox. The 5-petal flowers group together to form billowing heads of fragrant flowers and when the first large heads of flowers are finished blooming they can be trimmed to allow the side blooms room for their show. ‘David’ adds light and airy movement into the landscape and can be planted in herbaceous borders, among foundation plantings and as a low hedge to create rooms in gardens. The flowers bloom for almost 6 weeks in summer. The major pest is spider mites, especially in hot dry weather.

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

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

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

Mid-Season Aronia Twilight TourJuly 31, 2013 (5:00 p.m. to 7:30 p.m.)Location: Wye Research and Education Center, Queenstown, MDContact: Andrew Ristvey, 410-827-8056 x113More information is available at:extension.umd.edu/ipm/conferences

2013 FALCAN Truck and Trailer Safety SeminarAugust 14, 2013Location: Frederick Fair GroundsRegistration information: http://www.falcanmd.com/Forms.html

Summer Cut Flower TourAugust 6, 2013

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

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

LOCATION

Hibiscus moscheutos Bud Ellicott City (July 19)Sedum ‘Autumn Joy‘ Bud Ellicott City (July 19)

Plant Phenology: What is in bloom

Degree Days (As of July 19)Baltimore, MD (BWI) 1904 Dulles Airport 1936 Frostburg, MD 1232 Martinsburg, WV 1803 National Arboretum 2209 Reagan National 2209 Salisbury 2139

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.