TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers Commercial Horticulture August 1, 2014 In This Issue... - Weather update - Japanese beetles - Brown marmorated stink bug - Stinging caterpillars - Gypsy moths - Mosquito control - Cherry trees dropping leaves - Parasitic wasp - Tree crickets - Dog-day cicada - Linden lace bug - Lace bug on Amelanchier - Orangestriped oakworm - Bagworms - Scale update - Native plants and scale insects - Fall webworm - Crapemyrtle aphids Beneficial of the Week Weed of the Week Phenology Degree Days Announcements IPMnet Integrated Pest Management for Commercial Horticulture extension.umd.edu/ipm 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 Coordinator 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 Assistant 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) Weather Update What a contrast on weather across the United States. The western states are locked in the tenth year of a drought. Farms are desperate for water in California. Two weeks ago state water regulators passed the first-ever emergency water restrictions for the entire state. The rules levy fines of up to $500 a day on Californians who overwater their yards or hose down sidewalks and driveways. Over the long term, as climate change messes with weather patterns, California will likely experience longer and more severe droughts in the coming decades, threatening the sustainability of the state s main water supply system. The sector likely to be hit the hardest in Califorinia is agriculture which brings in nearly $45 billion each year for farmers and ranchers and accounts for about half of the fruits, nuts and vegetables grown in the United States. In 2014 alone, the current drought is expected to cost the agricultural sector about $1.5 billion in lost crop revenues and dairy and livestock value, according to a new economic impact study by researchers at the University of California at Davis. Meanwhile, here on the East Coast we are having one very wet summer. This pattern is great for tree growth but it is all resulting in heavier than normal disease incidence on landscape plants and vegetable crops. The amount of early blight fungus rocketed at the end of July with all the damp weather that makes perfect conditions for disease infection.
Japanese Beetles The population of adult Japanese beetles are peaking at this time and everyone is thankful for their impending departure. Unfortunately the females laid a high number of eggs into turfgrass and we expect a record number of grubs in lawns as we move into August. Also, plan on a large population of adult Japanese beetles next season. We had an e-mail about whether crushing Japanese beetles and leaving the dead bodies around your plants was a good idea or not. The person asked if you crushed the females would they release the pheromone in their body. Crushing the adult insect is fine. The female gives off a pheromone when she first emerges, and then is usually mated right away. The production of pheromone ceases right after mating. Keep in mind that when beetles feed Japanese beetle adults have been feeding heavily on the flowers of Hibiscus moscheutos here at the research center in Ellicott City on plants they release volatiles that induce more beetles to visit the plant to feed. Keeping the feeding damage down next year early in the season will help keep adult beetles from building up on plants. Brown Marmorated Stink Bugs The number of reports of brown marmorated stink bugs has plummeted this season. We are receiving very few reports of nymph activity this summer. If you see them causing damage in your area please contact Stanton at sgill@umd.edu. Stinging Caterpillars Steve Clancy found saddleback caterpillars in a landscape in central Maryland. The slug-like caterpillar with the bright green blanket-looking coloration on its back and spines on its anterior and posterior areas should be avoided in the landscape. The spines on the caterpillar can inflict a powerful sting. Control is not necessary just avoid touching the caterpillar especially the spines as best you can. The saddleback caterpillar is one of the caterpillars found in Maryland with stinging hairs Gypsy Moths Marty Adams, Bartlett Tree Experts, found a female gypsy moth laying eggs on red maple in Ellicott City on July 25. Remove and destroy egg masses where possible. Gypsy moth laying eggs on red maple trunk Photo: Marty Adams, Bartlett Tree Experts 2
Greenhouse Biological Program August 6, 2014 Stormwater Management Program August 20 and 21, 2014 Mosquito Control Steve Horn called to report a lot of activity from mosquito control companies spraying in Washington and lower Montgomery County this week. Many companies apply a mist of a pyrethroid in attempts to control mosquitoes. These applications would have a negative impact on beneficial organisms in the landscape. Cherry Trees Dropping Leaves We are receiving increasing numbers of emails and calls about ornamental cherries with premature leaf drop this season. The wet spring and summer has resulted in lots of activity from cherry leaf spot disease that causes early defoliation. There is not much you can do at this time of year. Fertilization will not help the tree unless there is a nutrient deficiency. One of the ways to prevent the early defoliation are protectant fungicide sprays applied early in the season but if rainfall is frequent, as it was in 2014, it would be a lot of fungicide spray applications. Generally the tree recoups the next season. If we had early defoliation for several years in a row the tree would be severely weakened. Parasitic Wasp I received a great picture of a giant Ichneumonidae wasp for identification this week. It is Megarhyssa macrurus that Wayne Noll sent in from an ash tree infested with borers in Rockville. This wasp inserts its long ovipositor into the tree and then inserts an egg into the borer larva feeding on the tree. This is biological control at work. Unfortunately, Wayne said the tree had to be chipped up, parasitized larvae and all. An ichneumonid wasp was found on an ash tree Photo: Wayne Noll, City of Rockville Tree Crickets Tree crickets start activity late in the season. Look for foliar damage on plants such as cherry laurel, euonymus and rhododendron. Unless the tree crickets are significantly damaging the plant, control is not necessary. If you do decide it s necessary to treat, a protectant spray should be used now. Tree cricket damage on cherry laurel Photo: Steve Sullivan, The Brickman Group 3
Dog-day Cicadas Marty Adams, Bartlett Tree Experts, found a dog-day cicada as it was emerging from its pupal case. You and your customers may see them dying on sidewalks, decks, and driveways this month. Predators such as birds and cicada killer wasps help keep dog-day cicada populations under control. A cicada killer wasp female catches and paralyzes a cicada and then takes it back to its hole and lays eggs in it. The developing wasp larvae start feeding on the paralyzed, but still living cicada. A dog-day cicada as it emerges from its pupal case Photo: Marty Adams, Bartlett Tree Experts A cicada killer is a main predator of cicadas Linden Lace Bug, Argaphia tiliae By: Nancy Harding, UMD Adult linden lace bugs (also called basswood lace bug) were found on Tuesday, July 22nd on the underside of leaves on littleleaf linden, Tilia cordata in Laytonsville. Lace bugs pierce the leaf with long, slender mouthparts and suck out the cellular contents. Feeding damage first appears as white stippling or tiny white spots. These spots later merge and leaves turn yellow. Also look for black or brown fecal spots they deposit on the undersides of leaves. Severe infestations may cause premature leaf drop. Control: Plants should be monitored regularly for signs of a lace bug infestation. Generally, Linden lace bugs adults and black fecal spots on the underside of a leaf Photo: Nancy Harding, UMD infestations on deciduous trees do not require treatment. However, if damage is heavy and lace bugs are actively feeding, treatment may be necessary. Get good coverage of horticultural oil on the underside of foliage to reduce populations. Systemic insecticides will give control. Many products are labeled for lace bugs. See more on lace bugs at: http://extension.umd.edu/learn/lace-bug-hg95#sthash.fi07cyzp.dpuf Lace Bugs on Amelanchier Bob Trumbule, Maryland Department of Agriculture, noted that in the July 18th report, amelanchier lace bug was reported, but that generally the lace bug we see on Amelanchier is the hawthorn lacebug; Corythucha cydoniae. Bob reports that other hosts for this species are Crataegus, Pyracantha, Cotoneaster, Pyrus, Sorbus, Cydonia, Cephalanthus, Malus and Chaenomeles. 4
Orangestriped Oakworm, Anisota senatoria By: Nancy Harding, UMD Orangestriped oakworm was found defoliating swamp white oak in Laytonsville on Wednesday, July 23rd. This native notodontid moth caterpillar prefers oaks, but will also attack hickory and birch. Young caterpillars feed in groups, whereas older caterpillars tend to spread out and feed on their own. Note that young caterpillars (1st and 2nd instars) are light colored and lack stripes, whereas later instar caterpillars have the characteristic orange striping (see images). All instars have the black horns behind the head. Small trees are sometimes defoliated completely by midsummer. As the caterpillars mature in late August or early September, they drop to the ground and are often seen crawling across sidewalks, driveways, and yards, etc. They pupate in the soil and overwinter in this stage. There are usually 2 generations per year. Orangestriped oakworm damage on swamp white oak - Quercus bicolor Photo: Nancy Harding, UMD Orangestriped oakworm (late instar) Photo: John Davidson, UMD Orangestriped oakworm (early instars) on swamp white oak Photo: Nancy Harding, UMD Control: If necessary, use a product containing Bacillus thuringiensis (Bt) for small larvae which are active now in many locations. Synthetic insecticides are needed to control large caterpillars. Also look for caterpillars that have been parasitized by wasps (=caterpillar mummies). If parasitoids are active you may not need to apply pesticides. If pesticides are applied be sure to select one that is less toxic to parasitoids. Bagworms Debby Smith-Fiola and Douglas Eller are reporting bagworm activity continues this week. Debby noted that she is not seeing an pupae yet. 5
Scale Update* Pine Needle Scale, Chionaspis pinifoliae (armored scale) The start of the second generation CRAWLERS of pine needle scale were found on Pinus mugo in Bowie on Tuesday July 22nd. Females with eggs are still abundant indicating crawlers may be active for a couple of weeks. The Degree Days in Bowie on July 22nd were 1602 DD. If degree day accumulations in your area are close to 1602 DD, closely monitor plants infested with pine needle scale. If you have active crawlers now is the optimal time to treat. There are 2 generations per year and this species usually overwinters in the egg stage under the female scale cover. Control: Many lady beetles and parasitic wasps feed on this pest; therefore, careful monitoring for predators and parasitoids, as well as using pesticides with little effect on beneficials, can allow biological control to suppress the population. However, if control is warranted, use a summer rate of horticultural oil or an insect growth regulator (IGR) such as Distance or Talus to target crawlers. Pine Oystershell Scale, Lepidosaphes pini (armored scale) The second generation of pine oystershell scale CRAWLERS and newly settled crawlers (1st instars) were found this week when monitoring pine oystershell scale (also called Oriental pine scale) on Pinus densiflora (Japanese red pine) in Laytonsville. The majority of these crawlers were under the basal sheath of last year s needles. As of Tuesday July 22nd the Degree Days in Laytonsville were 1848 DD. If the Degree Day accumulations in your area are close to 1848 DD and you have active crawlers now is the time to treat. There are 2 generations per year and it is reported that this species overwinters in the adult female stage; however, there is little known about its life history. Adult female pine oystershell scale (on left of top needle) with settled crawlers (1st instars) (top arrow) and crawlers (bottom arrow) Photo: Nancy Harding, UMD Monitoring: Monitoring for crawlers will be challenging since they hide deep in the needle sheaths. Look carefully. The adult female cover is oyster-shell shaped, straight or slightly curved, moderately convex, and light brown. The body of the female(found under the cover) is white; eggs and crawlers are white. Damage of the scale s feeding causes chlorosis at the base of the needles. Control: When crawlers are active, apply pyriproxyfen (Distance) or buprofezin (Talus) mixed with 0.5-1% horticultural oil for control. *Degree data totals as per Weather Channel website at http://www.weather.com/outdoors/agriculture/growing-degree-days/usmd0045 Native Plants and Scale Insects Last week, a landscape manager asked me to look at a planting of native tuliptrees that had been planted into a customer s landscape 3 year ago. The tree was covered in tuliptree scale with honeydew dripping off the foliage and sooty mold covering the leaves. The customer was upset that they had such a problem. They had been told native plants don t have problems like non-native plantings and chose these trees into their landscape. Guess what? even native species of tree have scale problems. The tuliptree scale is one of the largest soft scales we have on large shade trees. The females are swelling in size in late July and will start producing crawlers in August through September. Large numbers of these soft scales 6
may give an infested twig a warty appearance, as was seen at this site. One of the first indications of an infestation of this pest is the abundance of honeydew (sticky, sugar-rich material) secreted by developing soft scales during the growing season. Ant and wasp populations that seek the honeydew are often found in association with this soft scale insect. There were a number of wasps visiting the infested trees to harvest the honeydew. Ants may need to be managed since they protect this scale insect from predators and parasitoids. The honeydew is a substrate on which black sooty mold grows. The sooty mold may turn the leaves, twigs, and other surfaces beneath an infestation black. Feeding by this pest may weaken young trees by removing plant fluid. In some instances this species may be so prolific that it covers all of the twigs and branches which could result in a rapid decline of an infested tree. Look for tuliptree scale on tuliptree and magnolia; crawlers are active in late August through September Control options include applying either Distance or Talus when crawlers show up in August. Another option is to make a basal trunk application of soil drench of Dinotefuran to the trees. Since the tree blooms in spring there would no danger of impacting pollinators. The dinotefuran will last in the tree for 2-3 months and not be present by bloom time next year. Fall Webworm Marie Rojas, IPM Scout, is reporting first hatch of the second generation of fall webworm. She found them on Forest Pansy redbud in Frederick County this week. Control: The webbed branches can be pruned off and the webbing and caterpillars destroyed. There are numerous predators and parasitoids that attack and kill fall webworm. Bacillus thuringiensis (Bt), Confirm, or Conserve can be used for control, if necessary. The second generation of fall webworms hatched this week in Central Maryland Photo: Marie Rojas, IPM Scout Crapemyrtle Aphids We are receiving many e-mails that crapemyrtle aphids are increasing activity on crape myrtles in late July. Be careful not to apply neonicotinoids to crape myrtles at this time of year when they are in full bloom. The insect growth regular Talus is fairly effective on this aphid species. 7
Beneficial of the Week By: Paula Shrewsbury, UME Green assassin bug Pretty but dangerous (if you are an insect) Zelus luridus is a species of true bug (Hemiptera: Reduviidae) known as the green assassin bug (a relative of wheel bugs). There are about 60 known species of Zelus assassin bugs with five species occurring in North America. This week my assistant, Nancy Harding, found an egg mass of this predacious bug on foliage in a nursery. These predators and their eggs are often found on the foliage of trees in forests, landscapes, and nurseries. Adults and nymphs have elongate bodies (adults ~14-16 mm) with long narrow heads where you can find their beak-like mouth that is used to impale their prey. Adults are winged with a green-brown coloration where nymphs are an emerald green color. Egg masses are laid on leaves. The eggs have an elongate barrel appearance and a few dozen are glued together into a mass with a brown sticky substance. Zelus overwinters as nymphs, begin Egg case of the green assassin bug after the nymphs have hatched out Photo: Whitney Cranshaw, Colorado State University, Bugwood.org activity again in the spring, and adults appear in summer. The eggs found in the nursery this week will produce the emerald green nymphs that will overwinter. There is one generation per year. Zelus is a predator of other insects such as flies, wasps, sawflies, and caterpillars. It may behave as a sit-and-wait predator that ambushes its prey or it may actively hunt its prey. Zelus has an additional predation strategy. It creates sticky traps for its prey. The forelegs are adapted for grasping prey. First instar nymphs use the sticky substance from the egg mass to coat the hairs on their forelegs. Later instars produce a sticky material from glands on their legs. The sticky material help in catching prey items. Sounds like the making of Sci-fi movie to me! Note the long proboscis (beak-like mouth) of the green assassin bug nymph used to impale its fly prey Photo: Joseph Berger, Bugwood.org Although this green assassin bug nymph is beautiful with its emerald color and red eyes, it is equally deadly if you are an insect. Note that adults have wings. Photo: Joseph Berger, Bugwood.org Maryland Department of Agriculture Pesticide Container Recycling MDA has a brochure on the dates and details of the pesticide container recycling program which is available at: http://mda.maryland.gov/plants-pests/documents/recycle.pdf 8
Weed of the Week By: Chuck Schuster, UME Pokeweed, Phytolacca americana, is reaching high in many settings right now. It is a wonderful plant for creating dyes, but can be unsightly in landscapes and nurseries. This perennial weed is found throughout the eastern United States in many areas that are fertile, have moist but not saturated soils, and are not compacted. Pokeweed has many common names - pokeberry is one often used. It can grow to heights of nearly ten feet if left alone. It produces a large, deep, white taproot that can be three inches or more in diameter. The stems are most often hollow, smooth, and reddish to deep purple. When allowed to grow to the full potential the stems can reach diameters of four inches. The stems are branched on the upper portion of the plant. The leaves are large, alternately arranged on the stem and smooth. They have an elliptical shape and a shiny surface. Leaves can be longer than fifteen inches and are usually about one third as wide as they are long. All plant parts are toxic, including the roots and berries. Use caution when working with this plant. Control options for pokewed include 2,4D, Dicamba, and Garlon 4 which are all selective products. Caution with these products needs to be considered as they can potentially drift or volatilize and damage desired plant species. Glyphosate can be used, but is non selective and can damage any plant material with which it comes into, but valorization is not an issue as with other products. Be aware that exposed roots and suckers of desired plants can uptake these products and cause damage. Image showing size of a pokeweed plant (left) and a close-up of the leaf (right) Photos: Chuck Schuste,r UME PLANT PLANT STAGE (Bud with color, LOCATION First bloom, Full bloom, First leaf) Eupatorium perfoliatum (boneset) Bud August 1 (Ellicott City) Eutrochium purpureum (Joe pye weed) Bud with color August 1 (Ellicott City) Sedum Autumn Joy Bud with color August 1 (Ellicott City) 9
Degree Days (As of July 31) 2014 2013 2012 2014 2013 2012 Baltimore, MD (BWI) 2139 2260 2665 Dulles Airport 2031 2286 2576 Frostburg, MD 1320 1442 1692 Martinsburg, WV 2064 2118 2431 National Arboretum 2619 2599 3036 Reagan National 2619 2599 3036 Salisbury 2357 2524 2758 St. Mary s City 2228 2405 2822 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. Upcoming Conferences Greenhouse Biocontrol Conference*** August 6, 2014 Location: Maritime Institute, Linthicum, MD Fertilizr Applicator Recertification Seminar Location: Maryland Department of Agriculture, Annapolis, MD Time: 9:30 a.m. to 11:30 a.m. Choose any one of the following dates for recertification: August 7, 2014 or September 3, 2014 Seating is limited, register now. Cost: $12, which includes breakfast. Registration with payment is required no later than one week before the class date. For more information, call 410-841-5959. Stormwater Management Program*** August 20 and 21, 2014 TWO Locations: August 20 - Montgomery County Extension Office, Derwood, MD August 21 - Robinson Nature Center, Columbia, MD 2014 FALCAN Truck and Trailer Safety Seminar August 27, 2014 Location: Urbana Volunteer Fire Department, 3602 Urbana Pike, Urbana MD 21704 Program takes place both indoors and outdoors. Visit www.falcanmd.com to download a registration form. Email contacts; dfelice@synateksolutions.com or grove@ alpineservices.com *** For brochures and registration information on these programs CONTRIBUTORS: Stanton Gill Extension Specialist sgill@umd.edu Paula Shrewsbury Extension Specialist pshrewsb@umd.edu Karen Rane Plant Pathologist rane@umd.edu Chuck Schuster Extension Educator cfs@umd.edu David Clement Plant Pathologist hgic.umd.edu Andrew Ristvey Extension Specialist aristvey@umd.edu Ginny Rosenkranz Extension Educator rosnkrnz@umd.edu 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. The information given herein is supplied with the understanding that no discrimination is intended and no endorsement by University of Maryland Extension is implied. 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.