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Commercial Horticulture August 2, 2013Coordinator Weekly IPM report: Stanton Gill, Extension Specialist, IPM for Nursery, Greenhouse and Managed Landscapes, [email protected]. 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
TPM/IPM Weekly Report
- Weather update- Banded ash clearwing borer- Lawn fertilizer law - review and testing dates- Ambrosia beetles- Spider mites- Scale update- Black vine weevil- Liriope collapsing- White grub control is NOW- Japanese beetles- Dogwood sawflies- Moles in turf- Fall webworm- Cedar apple rust- Dusky birch sawfly- Millipedes- Cecropia moth caterpillar- A yellow katydid
Beneficial of the WeekWeed of the WeekPlant of the WeekDegree DaysPhenologyAnnouncements
A New Address for IPMnet
Integrated Pest Management for
Commercial Horticultureextension.umd.edu/ipm
WeatherWe finally are getting lower temperatures and a chance to dry out. Up to this point, it has been one rainy July. As a result, we are seeing lots of plants with root problems this season.
Banded Ash Clearwing BorerSteve Castrogiovanni, Mead Tree and Turf, called in to report that banded ash clearwing borers are pushing out copious amounts of frass on ash trees in Olney this week. The larvae are in a later stage at this point in the season and are clearing out a chamber to get ready for pupation. During this time they push large quantities of wood and frass from the gallery and it accumulates at the base of the tree. We should see adults out in late August to mid-September. Control: A protectant spray of permethrin or bifenthrin can be applied after adults are out.
When adult moths emerge, the pupal case is left behind on the trunk
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Lawn Fertilizer Law Manual Information on Maryland’s Lawn Fertilizer Lawn including review sessions and testing dates and a pdf version of The Professional Lawn Care Manual are available at: http://mda.maryland.gov/fertilizer The requirement for certification is October, 2013. Review sessions and testing dates are listed below:
Review Dates and Locations: There is no cost to attend, however, seating is limited and pre-registration is required. The review sessions are not designed as training sessions. Please do not attend the review session if you have not read the manual.
Testing Dates and Locations:
Annapolis Easton Derwood
July 31, noon-2:00 pm September 18, 12:30-2:30 pm August 22, noon-2:00 pmJuly 31, 2:30-4:30 pm September 18, 3:00-5:00 pm August 22, 2:30-4:30 pmAugust 9, 12:30-2:30 pm September 11, noon-2:00 pmAugust 9, 3:00-5:00 pm September 11, 2:30-4:30 pmAugust 16, 12:30-2:30 pmAugust 16, 3:00-5:00 pm
Yellowwood with frass tubes from ambrosia beetlesPhoto: Rich Anacker, A & A Tree Experts, Inc.
Annapolis
August 9, 2013August 16, 20139:00 am – 11:30 amMaryland Department of Agriculture50 Harry S. Truman ParkwayAnnapolis, MD 21401
Montgomery County
August 22, 2013September 11, 20139:00 a.m. – 11:30 a.m.University of Maryland ExtensionAgricultural Farm History Park18410 Muncaster RoadDerwood, MD 20855
Easton
September 18, 20139:30 – noonTalbot County Free Library100 West Dover StreetEaston, MD 21601
Ambrosia BeetlesRich Anacker, A and A Tree Experts, sent in a picture of a yellowwood tree that had frass tubes projecting from the trunk on July 26 in Baltimore. We have not had a chance to examine the tree yet, but this would be second generation damage from one of the Xylosandrus species of ambrosia beetles. In most years, we only see damage in spring with the first generation. Stressed plants growing in very dry or wet areas tend to be more susceptible.If you are seeing ambrosia beetle damage in your area please send in a picture to [email protected]. Thanks.
Spider MitesThe good news is that the number of spider mite reports has been dramtically lower this season with the frequent rains through July. It is always good to have some good news.
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Scale Update
White prunicola scale (WPS, armored scale): Monitoring WPS in Laytonsville on Tuesday July 30 found NO signs of crawler activity. The Degree Days per weatherchannel.com were 2080 DD. We will continue to monitor for the 3rd generation of crawlers.
Japanese maple scale (JMS, armored scale): Monitoring JMS in Laytonsville on July 30 found NO signs of crawler activity. Degree days per weatherchannel.com were 2080 DD. We will continue to monitor for the 2nd generation of crawlers. To aid in your monitoring of JMS see the fact sheet, Japanese Maple Scale - Woody Ornamental Host Plants, at https://www.extension.umd.edu/ipm/publications/landscape-publications
Black Vine WeevilAdult black vine weevils, Otiorhynchus sulcatus (Fabricius), are out and the females should start laying eggs in early August. While the adult weevils feed on foliage, often resulting in an unsightly appearance, the more serious damage is done by grubs (larval stage), which feed on the roots and may girdle the main stem, often killing the plant by girding it at the soil level. They have a strong preference for Taxus (yews), and various species of rhododendrons, but can also be found on Tsuga (hemlock), Pieris japonica (Japanese andromeda), Euonymus, Kalmia (mountain laurel) and Ilex crenata (Japanese Holly). In nurseries we have found them killing heuchera, toad lily, and sedums. They appear to have a strong preference for astilbe plants.Control of larvae: Soil drenches of bifenthrin will kill larvae. Paula Shrewsbury and Stanton Gill conducted trials using entomopathogenic nematodes to control the larvae in container grown perennial plants and obtained fairly good success using the entomopathogenic nematode, Heterorhabditis bacteriophora (Hb). Soil temperatures need to be warm (above 50 °F) to control the larvae so August through October is a good time to control the larvae if present in container grown plant material.
The fact sheet, Controlling a Major Nursery Pest-Black Vine Weevil, Otiorgynchus sulcatus (Fabricius), is available at https://www.extension.umd.edu/ipm/publications/nursery-publications
Liriope – CollapsingRecently we have been receiving pictures of liriope collapsing in the landscape. Liriope is extremely popular in the landscape and there are large plantings throughout residential and commercial landscapes. Leaf and crown rot of liriope can be caused by the fungus-like organism, Phytophthora and the fungal pathogen Fusarium. Most of the time it is Phytophthora that seems to collapse the plants. Early in disease development, affected leaves develop a pale green or yellowish cast. Later, the discoloration appears just above the rotted portion and extends towards the tip. Diseased leaves, particularly those in advanced stages of rot, are easily pulled free from the crown.Management: The most common predisposing factors for crown rot diseases include excessive moisture, deep planting, and other cultural factors that are stressful for plant growth. This year, abundant rainfall earlier in the season may have contributed to an increase in crown rot problems. It is important to examine plants for symptoms of crown rot before installing them in the landscape, i.e. don’t use plants that have yellow or brown leaves and check the roots to make sure they look healthy and white. Once established in the landscape it is very difficult if not impossible to manage root and crown diseases with fungicide applications. It is much more effective to avoid introducing potentially diseased plants, and to remove plants promptly, as soon as you notice crown rot problems. Managing irrigation to reduce the amount of time water may sit in the crown of the plant also may help lessen disease, i.e. irrigating early in the day, or the use of drip irrigation instead of sprinkler irrigation.
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A wheel bug feeds on a Japanese beetlePhoto: Rich Anacker, A & A Tree Experts, Inc.
Late instar dogwood sawfly larvae feeding on dogwoodPhoto: Leigh Cochrane, Master Gardener
Japanese Beetles - Biological ControlRich Anacker, A & A Tree Experts, Inc., sent in an image of a wheel bug feeding on a Japanese beetle adult in Ellicott City. Wheel bugs are one of the species of assassin bugs that are general predators of insects in the landscape and nursery.
Dogwood SawfliesDogwood sawflies continue to be active this week. Leigh Cochrane, Master Gardener, reported dogwood sawflies feeding heavily on three red twig dogwoods and pagoda dogwoods on August 2. The last instar of the dogwood sawfly larvae will go off the tree and find a place to pupate in the leaf litter. Control: Options include Conserve, synthetic pyrethroids, and carbaryl.
White Grubs: NOW is the time!If you have not monitored and /or treated for white grubs yet NOW is the time. White grubs are the immature stages of scarab beetles. In this area the most damaging white grubs are larvae of Japanese and Oriental beetles. White grubs can be a problem in lawn, golf, and nursery turf, and container and B&B nursery stock. I recommend you monitor your turf and nursery stock closely for white grub damage and activity. Monitor: If you have seen high densities of adult scarab beetle activity you should monitor now to determine if grubs are present. White grubs should be 1st and 2nd instars (~ ½ to ¾” in size) now. Dig soil cores or cut 1 sq. ft. sections of turf in areas for white grubs in the soil where adult scarab beetle activity has been high and/or irrigated turf appears drought stressed. Identify which species of grubs you have in your turf. White grub species can be identified by the rastor (hair) pattern on the underside of the abdomen. For help in grub identification go to http://ohioline.osu.edu/hyg-fact/2000/pdf/2510.pdf Control: If you have high scarab activity and / or have had historical problems with white grubs NOW is an optimal time to treat. The treatment window will only last another few weeks. If white grub control is warranted in turfgrass many of the neonicotinoids such as imidacloprid, clothianidin, and thiamethoxam are labeled and give good control. Mach2 is an insect growth regulator that provides good control of grubs. Acelepryn is a newer class of chemicals that has shown excellent control of grubs. Acelepryn has very low toxicity (no signal word required by EPA in MD). Once you get past mid-September the effectiveness of these products on the larger grubs goes way down. Remember to rotate the class of control products that you use to reduce the likelihood of insect resistance.
White grubs in turf feeding on rootsPhoto: Paula Shrewsbury, UMD
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MolesMark Schlossberg, ProLawn Plus, Inc., sent in a photo of a heavy mole infestation in turf. As the white grubs feed in the root zone, your customers may see mounds created by moles show up in their lawn areas. Moles feed on white grubs, but their primary food source are earthworms. Ohio State University has more information on moles at:http://ohioline.osu.edu/w-fact/0011.html
Cedar Apple RustJC Dyette, MRW Lawns, Inc., found a heavy infection of cedar apple rust disease on crabapple this week. The infection period was early in the season. Fungicide applications need to be applied when leaves are starting to expand in the spring. No control measures are applied at this time of year.
Fall WebwormRichard Chaffin, The Brickman Group, is reporting second generation of fall webworms in Baltimore County this week. Control: Bacillus thuringiensis (Bt), Confirm, or Conserve can beused for control. The webbed branches can be pruned off and thewebbing and caterpillars destroyed.
Dusky Birch SawflyTrisha Marty, Thrive, Inc., found the second generation of birch sawfly larve on birch trees in Potomac. This generation is active from July through early fall. The photo shows the characteristic s-shape when they are disturbed.Control: Conserve
Mole tunnels in turfPhoto: Mark Schlossberg, ProLawn Plus, Inc.
Fall webworm larvae within webbing on end of branchPhoto: Richard Chaffin, The Brickman Group
Cedar apple rust infection on crabapplePhoto: MRW Lawns, Inc.
Dusky birch sawflyPhoto: Trisha Marty, Thrive, Inc.
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Cecropia Moth CaterpillarAt this time of year, we often receive photos and reports of various caterpillars. Mark Kallal, USDA-Beltsville, found cecropia moth caterpillars (Hyalophora cecropia) feeding on Malus ‘Prairie Fire’. He noted that one caterpillar was over 3 inches long. This caterpillar feeds on a variety of woody plants.
A Booming Millipede PopulationWith all the rain, Todd Bolton, Takoma Park Arborist, reported an explosion of millipedes on a building in Takoma Park on August 1. He sent in photos of them crawling all over the building. Millipedes mainly feed on organic matter. They can sometimes be a nuisance when they get inside of buildings.
A high number of millipedes on a buildingPhoto: Todd Bolton, Takoma Park Arborist
A yellow katydidPhoto: Craig Greco, Yardbirds, Inc.
Cecropia moth caterpillarsPhoto: Mark Kallal, USDA-Beltsville
A Yellow KatydidCraig Greco, Yardbirds, Inc., made an interesting find this week. He found a yellow katydid sitting on top of a tire.
Beneficial of the Week, Paula ShrewsburyWho is helping us deal with all the white grubs? White grubs are the immature stage of scarab beetles and many white grubs are pests of turfgrass. Last summer and fall (2012) was a good year for scarab beetles and white grubs and therefore a bad year for turf managers. This year seems to be an even better year for scarab beetles which strongly suggests there will be an abundance of white grubs and significant damage as they feed on the roots of turfgrass. Turf managers should be monitoring closely for white grubs and their damage now. Be aware that you should also be monitoring for signs of natural enemies. There are a few common parasitoids that attack and kill white grubs, one of which is the Tiphia or Tiphiid wasps (Hymenoptera: Tiphiidae). Although there are 80 species of Tiphiid wasps in North
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Tiphia vernalis emerging from cocoonPhoto: Mike Reding & Betsy Anderson, USDA Agricultural Research Service, Bugwood.org
Third instar oriental beetle with Tiphia vernalis egg on ventral sidePhoto: Mike Reding & Betsy Anderson, USDA Agricultural Research Service, Bugwood.org
America, two species are primary parasitoids of white grubs, found in MD, and will provide some suppression. Each wasp species is specific to the grub species it attacks and the time of year it is active. Tiphia pygidialis, a native parasitoid, attacks masked chafer grubs and is active August through September. Whereas Tiphia vernalis was introduced into the U.S. in the 1920’s from Japan to control Japanese beetle grubs and is active in the spring from May to early June. The tiphiid wasp adults are about the size of a large ant, generally ½ - 5/8” long. They are narrow-waisted, and black with clear smoky wings. The females search for white grubs by flying over the turf, then burrow into the ground, and locate a grub by cueing in on species specific chemical odors left in the grub burrowing trails or present in grub frass. Both Tiphia species primarily attack 3rd instar grubs. Once a suitable grub is found the wasp stings it causing temporary paralysis. The wasp then lays an egg on the external surface of the grub. The location that the egg is laid on the grub body is very specific and differs between the two species. T. pygidialis lays it egg on the dorsal (upper) side of chafer grubs between the 2nd and 3rd thoracic segments. Whereas T. vernalis attaches its egg to the ventral (lower) side of Japanese beetle grubs between the 3rd thoracic and 1st abdominal segments. It is thought that evolution has selected for these locations because the grub is less able to “groom” the egg off of its body. The newly hatched larvae will then pierce the grub’s exoskeleton with its mouthparts and feed on the grub’s insides while the wasp itself develops externally leaving behind the sclerotized portion of the grub. It is a slow and sure death for the grub. Once larvae are fully developed they will form cocoons, overwinter in the soil, and emerge as adults the next year. Adult Tiphia are known to feed on the floral nectar of several plants such as wild carrot, peonies, forsythia, tulip poplar, and the honey dew deposited on leaves of plants from phloem sucking insects. Remember, Tiphiid wasps are beneficial and they won’t sting you. Leave them alone and let them do their biological control work on white grubs.
Weed of the Week, Chuck SchusterNodding beggartick, Bidens cernua, also often called bur marigold, has been a cause for some recent phone calls. A member of the Aster family, it is an annual is be found in many areas in the United States. This annual plant has a taproot; the stem can grow to three feet in height and has small fine hairs. The plant prefers damp sites. The leaves are sessile (without a petiole) and have a coarsely toothed leaf margin. Flowers will be yellow with five to eight petals. This plant reproduces only by seed. The seeds will occur with two downward facing
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Plant of the Week, Ginny RosenkranzWith downy mildew attacking the garden impatiens, finding shade loving annuals with color and texture became a challenge this past summer. Caladiums (Caladium bicolor) grow from tubers that can handle temperatures from 50° F on up and should never be planted until the ground temperatures are at least 50 - 55° F. Caladiums need light filtered shade with rich well drained soils between 6.0-6.5 pH and a light layer of mulch to retain soil moisture. The colorful leaves are heart-shaped and come in green with white splashes, green with red, green with pink and combinations of red, pink and salmon colored veins. Some of the more colorful leaves have splashes of color overtop other colors. The fancy leafed caladiums with the heart- shaped leaves are on long petioles raising the foliage to 12-30 inches tall, while the shorter strap-shaped leafed varieties are only 8-12 inches tall. Strap-shaped leafed caladiums are excellent in containers and window boxes where the plants are placed higher up while the fancy leafed caladiums are excellent as groundcover plants. Each caladium tuber has a central eye bud that can be removed before planting to allow the side buds to create a full plant with a multitude of leaves. Plants can be treated as annuals and left to die with the return of cold weather, but they can also be dug out of the landscape before the temperatures drop below 55° F, allowed to dry for a week out of the sun, then stored over the winter at temperatures above 60 °F. Some cultivars of merit include ‘Aaron’ - white with green margins, ‘Carolyn Morton’ - pink with red veins and green margins, ‘Pink Symphony’- pink with green veins and ‘White Queen’ which is white with red and green veins. Tuber rot can be a problem if caladiums are planted in soils with poor drainage and Anthracnose leaf spot can discolor some of the leaves. Leaf burn is a sign of too much sunlight or not enough soil moisture.
Nodding beggartick in bloomPhoto: Rob Routledge, Sault College, Bugwood.org
Caladium in containersPhoto: Ginny Rosenkranz, UME
barbed awns are flat and up to three quarters of an inch in length. They are brown in color.
Control of this plant include preventing seed formation This will work well in turf, but in landscape setting use of post emergent non selective products is the primary means. Casoron will control plant as it is labeled to control aster family weeds, but must be incorporated by irrigation of mechanical means.
Degree Days (As of Aug 1)Baltimore, MD (BWI) 2283 Dulles Airport 2308 Frostburg, MD 1460 Martinsburg, WV 1998 National Arboretum 2655 Reagan National 2655 Salisbury 2549
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.
Stanton GillExtension Specialist
Paula Shrewsbury Extension [email protected]
Ginny RosenkranzExtension [email protected]
Chuck SchusterExtension Educator
Karen Rane Plant [email protected]
Andrew RistveyExtension [email protected]
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
2013 FALCAN Truck and Trailer Safety SeminarAugust 14, 2013Location: Frederick Fair GroundsRegistration information: http://www.falcanmd.com/Forms.html
Greenhouse ConferenceNovember 7, 2013Location: Chesapeake College, Wye Mills
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
Eutrochium purpureum (Joe Pye Weed) Full bloom Ellicott City (July 30)Sedum ‘Autumn Joy’ First bloom Ellicott City (Aug 2)
Plant Phenology: What is in bloom
