for Arborists, Landscape Managers & Nursery Managers

Commercial Horticulture June 14, 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

- Hibiscus sawfly- New web address- American hollies- Daylily leaf streak- Brown marmorated stink bugs- Japanese beetles- Scale updates- Bagworms- Flea beetles- Slugs- Regal moth

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

Hibiscus SawflyDebby Smith-Fiola, IPM Scout, found hibiscus sawfly adults on hibiscus in a nursery in Washington County this week. Here at the research center in Ellicott City, there are a lot of larvae feeding on Hibiscus moscheutos. It is one of the higher sawfly populations on these plants in recent years. Look for small, pale green larvae on foliage. Intial damage are small shotholes, but as the sawflies continue feeding, they skeletonize the foliage. Heavy infestations can defoliate the plants.Control: Conserve will work for sawfly larvae control. Remember that since sawflies are related to bees and wasps, not to caterpillars, Bt will not work.

Adult hibiscus sawflyPhoto: Debby Smith-Fiola

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HollyIn early May we put out reports that American hollies had a lot of yellow, spotted leaves which subsequently dropped off the plants and left the American holly trees looking rather bare. We received many e-mails concurring with what we were reporting on the American Holly – they looked bad. Now we have had a month pass and the new foliage on the American hollies have emerged and fully expanded making the trees very attractive again. There is nothing you need to do at this point and the holly trees should continue to look good through the growing season.

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.

Japanese beetle on aroniaPhoto: Andrew Ristvey, UME

Daylily Leaf StreakDaylily leaf streak is showing up with greater frequency with the wet weather. Daylily leaf streak is a fungal disease caused by the pathogen, Aureobasidium microstictum. Cultivars vary in susceptibility to this disease- in extreme cases on highly susceptible cultivars, virtually all of the foliage can be affected. The pathogen overwinters on infected leaves and is spread by splashing water from overhead irrigation or rainfall. Management: Fungicides effective in protecting uninfected leaves from this disease include thiophanate methyl (Cleary’s 3336 and others), chlorothalonil (Daconil), and azoxystrobin (Heritage). For maximum effectiveness, fungicides should be applied starting when new growth is emerging.

Brown Marmorated Stink Bug UpdateBrown marmorated stink bugs are now mating and laying eggs outside. They often lay eggs in clusters of 28. It is common for these egg clusters to be laid in an ‘arrowhead’ pattern. When first laid, they have a bluish white color and then turn white before hatching. If you find discolored eggs, they have been parasitized or killed by some other cause.

Brown marmorated stink bug eggs laid on Kwanzan cherry (left) and a second instar nymph which is black, but with the characteristic white bands on the antennae (right)

Japanese BeetlesSo far this season, we haven’t had reports of too much Japanese beetle activity. Andrew Ristvey, UME, is finding beetles on aronia this week.

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Scale Updates

White prunicola scale (WPS, armored scale): Monitoring WPS populations on Tuesday June 10 in Laytonsville found mostly 2nd and 3rd instars; therefore, because of the hard wax covering they are very difficult to control at this time. Degree day readings according to weather channel.com in Laytonsville as of June 10 were 765 DD. We will continue to monitor WPS scales for the next generation of crawlers. Japanese maple scale (JMS, armored scale): Monitoring of JMS in Laytonsville and Adamstown on Tuesday June 10 found the first generation of CRAWLERS. There were a greater number reported in Adamstown; however they are just beginning to hatch. At one location, blue tape was used on the trunk to detect the first crawlers. Because JMS emerge over a long period of time, it would be best to hold off applying pesticides until larger populations of crawlers emerge. We will continue to monitor and provide an update next week. Monitoring: Check the degree day accumulations in your area and if they are close to 765 DD you should look for active small, oval, soft bodied and purple crawlers on the bark, both trunk and branches and sometimes in heavy infestations on the leaves.

For more information monitoring and management of JMS go to: https://www.extension.umd.edu/sites/default/files/_docs/programs/ipmnet/JapaneseMapleScale-UMD.pdf

Indian wax scale: Monitoring of Indian wax scale on June 11 (728 DD) found this scale to still be in the egg stage. They should be in crawler stage very soon.

Juniper scale: Monitoring of juniper scale found one live adult, all the rest are dead. There were nine parasitized adult covers found. There was one first instar crawler and 119 2nd instar settled crawlers. The susceptible stage for controlling scale at this time of year are the first instar crawlers.

Early instar bagworm

Imprelis UpdateMichigan State published an article on the aftermath of the Imprelis problem that occurred in 2011. If you used Imprelis on your customer’s lawn then you might want to read this article.http://msue.anr.msu.edu/news/imprelis_update_for_spring_2013

BagwormDebby Smith-Fiola, IPM Scout, found second instar bagworm larvae on plants in Washington County on June 11. Control: Now is the time to apply Bt or Conserve.

Flea BeetlesFlea beetles are damaging hibiscus this week in Ellicott City. Adults are chewing shot holes in leaves. Monitoring: Look for adult flea beetles on the upper sides of foliage and shothole damage to foliage. Control: Mature plants should recover from damage and control is not usually warranted. Applications of Azatin can be used to reduce flea beetle populations.

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Slug on epimediumSlug damage on irisPhoto: David Clement, HGIC

SlugsThe rains have been heavy and fairly frequent in June which is causing an increase in slug and snail feeding on herbaceous annual and perennials plant material in the landscape.

Slug reduction starts with sanitation - Slug populations can be reduced by eliminating their breeding and hiding places. Unfortunately as people create dense plantings this also creates ideal conditions for slugs and snail populations. Slugs and snails love to hide under large rocks and objects left laying in the garden. The goal is to reduce the shelters for slugs. As much as possible try to remove logs, pots and other debris from the area. Encouraging toads in the garden helps reduce slug populations. Also, lightening bug larvae feed on slugs in the gardens.Traps – For avid gardeners with lots of energy place boards or other flat objects on the soil in the garden. These trap boards should be at least 6 by 6 in. Each morning remove the slugs from beneath the traps and destroy them. Beer or yeast in a can? Many articles mention placing a can in a landscape and placing beer in it to attract slugs. This does attract them and they can drown in the liquid, but the can needs to be emptied regularly. This is probably not practical in most cases.Pesticides – For best control, apply the molluscicide, usually a pesticide mixed with a bait formulation, and place the material under boards or a trash can lid to prevent non-target animals from finding and injesting the baited molluscicide. Two or more treatments at 5 to 7 day intervals may be necessary to obtain adequate control. In the list below are pesticide formulations labeled for slug control. Many people have home vegetable gardens and slugs will be present in the garden plot area. Before using a pesticide in a vegetable garden, check to be sure it is labelled for that use. Do not use Mesurol or Metaldehyde products around pets unless the baited material is placed under a board or trash can lid to prevent pets from contacting or injecting the bait. Iron phosphate products are labeled safe around pets, but efficacy reports have been variable. Table salt applied to slugs will kill them but is not labeled for this use and excessive amounts could affect soils. See Paula Shrewsbury’s ‘Beneficial of the Week’ for information on biological control of slugs.

Regal MothGinny Rosenkranz, UME, sent in this photo of a regal moth. Its caterpillar is the hickory horned devil that has prominent, but painless, orange ‘horns’.

Regal mothPhoto: Ginny Rosenkranz, UME

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Beneficial of the Week, Paula ShrewsburySlugs - What eats those slimy gastropods?We are having some wet weather and the slugs are very happy and active. Slugs are gastropod molluscs. Biologically slugs are somewhat interesting organisms. For example, their use of muscular contractions for locomotion, and they are hermaphrodites. Basically, each individual slug has male and female reproductive parts. Two individual slugs exchange sperm and both produce eggs. Slugs are not usually thought of fondly by many… first because they eat and damage plants, followed by the fact that they produce slimy mucus – which is somewhat disgusting. When controlling slugs, the use of baits is the more common tactic. However, it is important to know that other organisms eat slugs and provide some level of biological control. For example, some frogs, toads, snakes, hedgehogs, salamanders, turtles, rats, and birds consume slugs. Some slugs are carnivorous and are predators of other slugs and snails. Carnivorous slugs will follow the slime trail of another slug as part of its hunting strategy. Beneficial nematodes, such as Phasmarhabditis hermaphrodita, are commercially available (may not be available yet in the U.S.) and target several common slug species. Juvenile stages of the nematodes actively search for slugs. Nematodes enter the slug through the breathing pore (pneumostome) in the slug’s mantle. Nematodes release bacteria into the slug which stop the slug from feeding and eventually kill it, and the nematodes feed on the bacteria. This is a nice mutualistic relationship that benefits everyone but the slug. There are a few entomologists conducting research on nematodes as biological controls for slugs. Hopefully, in the near future using nematodes will be viable control option. There are flies known as marsh flies (family Sciomyzidae) whose larvae are active in soil and are predators or parasites of snails, snail eggs, and slugs. The larvae of some species of ground beetles (family Carabidae) and rove beetles (family Staphylinidae) are carnivorous and actively hunt slugs, worms and other insects. These beetles are frequently found under logs or stones, in soil, and other habitats that also favor slugs. Lady beetles have also been seen feeding on slugs. Encouragement of these predators by providing habitat, combined with other tools such as sanitation, handpicking (yuck), traps, barriers, and baits, will help in the battle against these little slimers.

Weed of the Week, Chuck SchusterPoison hemlock, Conium maculatum, is the weed for this week. A biennial plant with a tall erect growth habit, the first-year poison hemlock is a basal rosette, and the following year a flower stalk that is what becomes most noticeable. This stalk can reach ten feet in height. This plant is found throughout the United States and is very poisonous to livestock. The leaves are alternate with a basic triangular outline, five to fifteen inches in length, occurring on a petiole, and pinnately compound. Each of the individual leaflets are lanceolate in outline and one eighth to one quarter in length. The flowering stalk is hollow, ridged and has purple spots. White flowers are one and one half inches to two and one half inches in diameter, arising from flower stalks. These flowers are made up of a cluster of smaller flowers all arising from a common point. The root system is a white, solid thick taproot. This plant is very similar to giant hogweed.

Control of poison hemlock may be achieved in turf using 2 4D compounds. In landscape and nursery settings glyphosate will provide control. Remember to be cautious when using glyphosate close to the stems of landscape shrubs and trees.

Poison hemlock flowers and foliagePhotos: Chuck Schuster, UME

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Plant of the Week, Ginny RosenkranzAlchemilla mollis, lady’s mantle, is a shade and moist soil loving herbaceous perennial that can become a wonderful groundcover. The soft green colored foliage has shallow lobes, jagged edges and soft velvety hairs that make the leaves very strokeable. The foliage also collects water in the center of the leaves, held up in round balls by the velvety hairs. In the heat of summer this can lead to moisture related fungal diseases. The small yellow green flowers are held up on stiff stems, suitable for cutting and last 2- 3 weeks in the garden. Blooming from late May to early June, flowers are held above the foliage and create a drift of yellow green flowers over soft green foliage. The plant itself grows 12 to 18 inches tall and wide and is cold tolerant from USDA zone 4-7. It is tolerant of many soil pH as long as soil moisture remains constant.

Alchemilla mollis in bloomPhoto: Ginny Rosenkranz, UME

Degree Days (As of June 13)Baltimore, MD (BWI) 939 College Park 1160Dulles Airport 980 Frostburg, MD 550 Martinsburg, WV 891 National Arboretum 1160 Reagan National 1160 Salisbury 1117

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

Aesculus parviflora Full bloom Silver Run (June 14)Agastache foeniculum First bloom Ellicott City (June 14)Aruncus dioecus Full bloom Silver Run (June 14)Asclepias tuberosa Bud Ellicott City (June 14)Coreopsis verticillata ‘Moonbeam’ Full bloom Ellicott City (June 14)Echinacea tennesseensis Full bloom Silver Run (June 14)Indigofera decora Full bloom Silver Run (June 14)Leptodermis oblonga Full bloom Silver Run (June 14)Mitchella repens Full bloom Silver Run (June 14)Spigelia marrilandica Full bloom Silver Run (June 14)Stewartia pseudocamellia First bloom

Full bloomEllicott City (June 10)Ellicott City (June 13)

Syneilesis aconitifolia Full bloom Silver Run (June 14)Thermopsis caroliniana Full bloom Silver Run (June 14)Zenobia pulverulenta ‘Woodlanders Blue’

Full bloom Silver Run (June 14)

Plant Phenology: What is in bloom

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

MNLA Nursery Field DayJune 20, 2013Location: Waverly Farm, Adamstown, MDContact: MNLA, 410-823-8684

The Maryland Christmas Tree Association (MCTA) Summer Christmas Tree MeetingJune 22, 2013Location: Jarrettsville Nurseries, 1121 Holy Cross Road, Street, Md 21154. Topics include: irrigation practices, field preparation, field tours, advanced shearing, fertilizer programs, pesticide and IPM. 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, MD 21042Contact: Andrew Ristvey, aristvey@umd.edu, 410-827-8056 x113

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