TPM/IPM Weekly Report

Transcription

1 TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers Commercial Horticulture August 30, 2013 In This Issue... - Weeds and herbaceous perennials - Spider mites needed - Lawn fertilizer law - Scale update - Banded ash clearwing borer - Cyanobacteria - Spangle oak gall - Lichens - Invasive species - Bagworms - Ambrosia beetles - Caterpillar activity - Cypress midge gall - Cercospora leaf spot - Hemlock woolly adelgid - Oriental bittersweet - Lawn fertilizer law - Biological control activity Beneficial of the Week Weed of the Week Plant of the Week Degree Days A New Address for IPMnet Integrated Pest Management for Commercial Horticulture extension.umd.edu/ipm Coordinator Weekly IPM report: Stanton Gill, Extension Specialist, IPM for Nursery, Greenhouse and Managed Landscapes, sgill@umd.edu (office) or (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) Weeds and Herbaceous Perennials The regular rains this summer has made conditions perfect for weeds to flourish in many herbaceous perennial planting beds. This fall, a number of weeds will be germinating that will grow with great vigor next spring. Now is the time to be applying pre-emergent herbicides to prevent fall germination of weeds. Some herbaceous perennials are sensitive to some of the pre-emergent herbicides. To help you sort this situation out, there is a publication on Total Plant Management of Herbaceous Perennials. There is a section in this manual written by Andrew Senesac, Cornell University. in which he lists pre-emergent herbicides that can be safely used around various perennials. An electronic copy is available at If you would like a printed copy of this manual it is $25. Ordering information is posted to the webpage. Plants With Spider Mites Needed for Research Paula Shrewsbury and Nancy Harding are in need of spider mites to conduct a research trial. This could be twospotted spider mite, boxwood spider mite, southern red mite, etc. 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 They need 15 to 20 plants with mites and plants can be in nurseries or landscapes. If you possibly have a site contact Nancy Harding at nharding@ umd.edu. Thanks.

2 Scale Updates White prunicola scale (WPS, armored scale): Monitoring WPS in Laytonsville on Wednesday August 28 found NO signs of crawler activity. The Degree Days per weatherchannel.com were 2696 DD. We will continue to monitor for 3rd generation crawlers. Japanese maple scale (JMS, armored scale): Monitoring JMS in Laytonsville on Wednesday August 28 found about 55% crawlers and 1st instar settled crawlers, 25% 2nd instars, and 15% adult females with eggs and 5% without eggs. The Degree Days per weatherchannel.com were 2696 DD. Therefore, if the degree day accumulations in your area are near or at 2696 DD and you have not treated your plants infested with JMS and there is crawler activity, this still would be optimal timing for control applications. Once these scales move into 2nd instars (estimate within a week) the efficacy of control measures goes down. JMS has a wide host range. Look for them on dense plants such as bush roses and blue hollies. You want to get on top of the problem immediately because populations explode quickly. Control: We suggest using either Distance or Talus insect growth regulators since they are found to be effective and have less negative impact on beneficial organisms than some other chemical options. In 2012 we conducted trials to evaluate materials for control of Japanese maple scale. Dinotefuran applied as soil drenches and basal bark drenches gave good control of this scale. We treated crabapples that were heavily infested with scale. Treatments were made in May. To aid in your monitoring and management of JMS see fact sheets: Japanese Maple Scale - Woody Ornamental Host Plants Japanese Maple Scale - A Pest of Landscape Trees and Shrubs Tuliptree Scale: Tuliptree scale was found on deciduous magnolia in Montgomery County this week. There were eggs present, but no crawlers yet. Females are feeding heavily and producing a lot of honeydew so there is a lot of sooty mold on foliage. This scale can be controlled with applications of Distance and 0.5% horticulutral oil. Another option is to soil inject imidacloprid into the root zone or trunk injection. Tuliptree scale on magnolia Cryptomeria Scale: We received a report on the stages of cryptomeria scale on Koren fir in Central Maryland. This scale also infests cedar, chamaecyparis, cryptomeria, pine, spruce yew, and hemlock. There were plenty of females with eggs, but no crawlers yet. Movement was noted within the eggs so they are close to hatching. It is the second generation for this armored scale. Cryptomeria scale overwinters as immatures on the needles. Control: Apply Distance or Talus sometime in the next week. 2 Damage from this scale causes yellow banding on needles

3 Banded Ash Clearwing Borer We have baited pheromone traps in Westminster and Brookeville for detecting banded ash clearwing moth adult flight activity. So far, the traps have not caught any adult male moths. We generally see activity in late August to early September, but the late spring and cooler summer has delayed emergence. Strange Blue-Green Algae (Cyanobacteria) Thanks to each of you who responded to issue on cyanobacteria in nurseries. I received several s reporting it as a problem in Maryland and from one garden center in Delaware. Last week I reported that Michigan State University Extension had published an article that several Michigan nursery container growers were having a problem with a slimy-when-wet, blue-green Nostoc spp. of algae These are not your typical aquatic forms of algae that inhabit irrigation ponds or streams, but are ones that survive in terrestrial sites. In fact, they are not even classified now as algae, but are called cyanobacteria because they can conduct photosynthesis like higher plants. They are considered to be among the most ancient organisms to inhabit the earth with some fossil records showing they have been on earth for over 3.5 billion years. Several people asked about how to control this cyanobacteria. Good question, but I don t think there is a really good control at this point. Thomas Dudek of Michigan State Extension had these suggestions: Chemical controls that have been reported in the literature include the following. Fungicides like mancozeb and chlorothalonil when applied on a 7- to 14-day schedule on golf course putting greens have shown to create some relief, but need to be reapplied if conditions become favorable. Copper sulfate at 1.3 oz./gallon of water per 1,000 sq. feet has also been reported to be effective if reapplied every 7 to 14 days. I (Thomas Dudek) have also seen some benefit when applying sodium carbonate peroxyhydrate granules to this organism. The cyanobacteria must be wet prior to application. I checked on-line for products from Bioworks and they have a new product called PERpose Plus which is a specially formulated hydrogen peroxide (or hydrogen dioxide) based product for prevention and control of plant diseases and algae pre-harvest and post-harvest on crop plants, hard surfaces, and potting media. Since this product is labeled for nursery hard surfaces, such as growing beds, and for algae control it might be worth a try. If you do try it out send me feedback on how effective it is. Send an to sgill@umd.edu or call me at Joanne Lutz, Griffin Grower Supplies, mentioned that they were having growers try applying these products to the cyanobacteria: Green Clean Pro Sodium Carbonate Peroxyhydrate and Kleengrow Didecyl dimethyl ammonium chloride Spangle Oak Gall Trudy Haselhuhn, Gallaudet University, sent in a photo of an oak with spangle oak galls on the leaves. These round saucer-shaped galls are caused by a cynipid wasp. Control: Control is not necessary. Spangle oak gall Photo: Trudy Haselhun, Gallaudet University 3

4 Did you hear the story of a fungus meeting algae, and they took a Lichen to each other? From: Andrew Ristvey, UME It s true. The blue-gray and green growth, often seen on the sides of trees and other places like rocks and fences are mutualistic symbiotic organisms collectively called lichen (pronounced liken ). There is no need to fear these organisms as they very seldom to never cause any detriment to the trees they inhabit. Often living on the north side of trees and other surfaces (avoiding heat and thriving on the more moist locations), lichens are naturally occurring and can be quite attractive. An excellent way to tell direction if you are lost in the woods! Biologically speaking, lichens are a symbiotic, specifically mutualistic, relationship between a member of sac or club fungi and either green algae, cyanobacterium or sometimes brown algae. The mutualism they share begins with the fungi creating an environment for the algae to live, including moisture retention and a substrate to grow. The algae, in return, produce carbohydrates from photosynthesis which the fungi can consume. What you see on a tree, rock or fence are most often the vegetative structures called thalli (plural of thallus) and look like a scaly mat. Sometimes the reproductive structures called apothecia are noticeable. Lichens can be flat, but are usually three-dimensional and layered, sometimes having structures looking like balloons or like fingers. One can identify specific lichens based on their growth patterns. Lichens have inhabited every corner of the earth. So long as they have a surface on which to form, time to grow and very, very clean air, they do well. Interestingly, lichens are a bellwether for air pollution. If you see lichens growing on trees, it usually means that your air quality is high. So actually, seeing them is a good thing. Additionally, many animal species utilize lichens from nesting material to food. Do lichens damage plants? Not typically. But, as noted in an Ohio State Extension Bulletin (Special Circular ), they may have some negative effects. Since they are encrusting life-forms, they may possibly be unsightly on trees that are grown specifically for attractive bark. However, the beauty of lichens on bark should also be considered and appreciated. In some cases lichens may have an indirect and undesirable affect when they may be part of a pest s life cycle as in the case of the hemlock looper, (Lambdina fiscellaria). Additionally, algal and fungal plant pathogens which cause scurfy leaf spots and fissured twig cankers on many plants may actually form a symbiotic relationship similar to lichens. However, this is not the norm. Lichen control, if necessary, can be done by management of plant health. Lichens can be an indicator of declining plant health where thinner canopies increase light penetration to the branches, promoting lichen growth. Pruning declining limbs may also be a way to slow the progress of the lichen. Kocide is a fungicide/ algicide that is labeled for use on lichen on specific conifers only, but no other chemicals are labeled. For what it is worth, teach your clients that lichens are a benevolent part of nature in most cases, and that they show how healthy the environment is around them. Information from this article was partially retrieved from the Ohio State University Extension Bulletin Special Circular by David J. Goerig and James A. Chatfield. 4

5 Invasive Species We have emerald ash borer, brown marmorated stink bug and boxwood blight, but we also have an invasive species in our streams. The northern snakehead is now found in the majority of streams in Maryland and Virginia and has been reported as far north as Maine and south to Florida. The speed at which this invasive species spread throughout the streams of the East Coast is astounding. It is a native of China and Korea and it is thought it was a deliberate introduction. On August 13, 2013 Caleb Newton reeled in a record-breaking 17-pound, 6-ounce northern snakehead fish that he caught in Aquia Creek, a tributary of the Potomac River in Northern Virginia. This is a new world record beating a 2004 record in Japan by 2 ounces. On August 14 an article in the Washington post reported that snakehead, which feed on other fish, have contracted a virus. You would think this would be good biological control, but this virus does not kill snakehead but it is transmitted to bass which it does kill. This invasive species not only feed on game fish, but now it is spreading a virus that kills other fish. DNR is encouraging anglers to kill any snakehead they reel in to try to reduce the numbers of this invasive predator fish. On Sunday, at the Olney Farm market a visiting chef showed the group how to grill snakehead fish. I tried it and it actually tasted pretty good. Maybe a solution is to make it so popular for eating that it is fished out for food. The snakehead is just another example of the danger of introducing invasive species into a new environment where it has no natural predators or parasites to keep it under control. The snakehead fish is also a reminder of why we need to be constantly vigilant for new, invasive non-native insects, weeds and diseases that can move into our nurseries and landscapes. If you find a new pest (insect, disease or weed) in your nursery do not just ignore it. Please continue to work with us at the University of Maryland Extension and the Maryland Department of Agriculture in identifying pests so we can try to prevent a dangerous new problem from getting established and causing economic loss. Bagworms There is no real feeding activity of bagworms this late in August. Customers may notice the large bags as we move into September, but this is not the time to control them. The bags can be hand removed, but do not waste time trying to spray for bagworms now. Bagworm on crabapple Ambrosia Beetle Activity Continues We received photos showing activity of the third generation of ambrosia beetle. The frass tubes on the trunks of Kousa dogwoods were signs of a heavy infestation. Frass tubes on Kousa dogwood in a nursery 5

6 Caterpillar Activity Continues Puss Caterpillars We received a report from Frederick of puss moth caterpillars, Megalopyge opercularis, on Dragon Lady hollies. In the past we have had reports of these caterpillars mainly on the Eastern Shore. Avoid handling this caterpillar because it has stinging hairs and can cause a severe rash. There are light brown and dark brown color forms of this species. If you have a report or photo, please send it to Stanton Gill at sgill@umd.edu. Eastern Tiger Swallowtail Caterpillar Douglas Eller, Moon Nurseries, sent in a photo of an Eastern tiger swallowtail that he found. These caterpillars are not often found in high numbers. Plant hosts include tuliptree, magnolia, cherry and ash. Eastern tiger swallowtail caterpillar Photo: Douglas Eller, Moon Nurseries, Inc. White Flannel Moth Caterpillars Grady Reed, Thrive, Inc. reported that he found large numbers of white flannel moth larvae, Norape ovina, on redbud trees in Potomac on August 23. Flannel moth caterpillars have fine long, silky hairs that conceal venomous setae which can cause serious skin irritations. Flannel moth larvae feed on a variety of trees and shrubs including black locust, elm, hackberry, redbud, dogwood, and red maple. Young larvae feed gregariously; older larvae are often found feeding singly. The puss caterpillar mentioned above is the other flannel moth caterpillar species found in Maryland. Generally, these caterpillars do not occur at levels that require control, but keep an eye out for them to avoid any skin irritations from the stinging hairs. Orange Striped Oakworms Gregory Dione, Mainscapes, Inc., sent in photos of orangestriped oakworms he found in Columbia this week. The caterpillars should be finishing up feeding very soon. Paula Shrewsbury covers a parasitic wasp that feeds on this species in her Beneficial of the Week. The bright colors make this caterpillar fairly easy to spot. Photo: Grady Reed, Thrive, Inc. Orangedstriped oakworms Photo: Gregory Dionne, Mainscapes, Inc. 6

7 Yellownecked Caterpillars John Speaker, Speaker Gardens, brought in a sample of late instar yellownecked caterpillars that were feeding on upright birch at a site in Montgomery County this week. Here at the research center in Ellicott City, we have been monitoring several clusters of larvae feeding on small oaks. Overnight from Thursday to Friday, a group molted and left their cast skins in a group along an abandoned stem. They defoliate sections of trees, but at this point in the season the foliage has been on the plant long enough that the long term damage to the tree is minimal. Cypress Twig Gall Midge John Speaker, Speaker Gardens, brought in a sample of bald cypress with galls caused by the cypress twig gall midge along the branches. Control: Usually not necessary. Pruning can be done to reduce the number of galls present. There are several species of wasps that parasitize gallforming insects and help reduce the number of galls formed. Timing of chemical controls is critical because applications need to be made before galls begin to form. Yellownecked caterpillars showing larvae on August 29 (left) and August 30 (right) after molting overnight Fall Webworms Fall webworms are nearing the end of their feeding time for the season. Leigh Cochrane reported them infesting a small tree on a patio. We have observed them on many trees including mulberry and blackgum here at the research center. You can prune off infested branches if necessary. Look for caterpillars moving through the landscape in search of places to pupate and overwinter. Galls on Oak That Look A Lot Like Acorns There are galls found on oaks that look a lot like acorns. The galls are caused by a cynipid gall wasp, Adleria strobilana. They develop after the wasps hatch and begin feeding along the stem. The galls start out yellow, turn pink to red and eventually turn brown. 7

8 Cercospora Leaf Spot Jeff Schwartz, Ashton Manor Environmental, sent in photos of crape myrtle infected with cercospora leaf spot. Since the appearance of symptoms is usually delayed until late summer to early fall, protective fungicide sprays are rarely needed for the control of this disease. Frequent rains is making this disease rather common this year. Cercospora leaf spot on crape myrtle leaves Photo: Jeff Schwartz, Ashton Manor Environmental Hemlock Woolly Adelgid Jenn Rodriguez, Ruppert Landscape, found hemlock woolly adelgid infesting a mature hemlock in Roland Park this week. There are two generations per year in Maryland. The second generation of crawlers will be active in late September or early October. Hemlock infested with hemlock woolly adelgid Photo: Jenn Rodriguez, Ruppert Landscape Oriental Bittersweet Look for Oriental bittersweet in the nursery. It has produced blooms and is starting to go to seed now. Pull it down before plants go to seed. It is very active and vigorous this year due to the wet weather Lawn Fertilizer Law 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: 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. Montgomery County September 11, :00 a.m. 11:30 a.m. University of Maryland Extension Agricultural Farm History Park Muncaster Road Derwood, MD Easton September 18, :30 noon Talbot County Free Library 100 West Dover Street Easton, MD Testing Dates and Locations: Easton September 18, 12:30-2:30 pm September 18, 3:00-5:00 pm Derwood September 11, noon-2:00 pm September 11, 2:30-4:30 pm 8

9 Biological Control Activity Robber Fly Marty Adams, Bartlett Tree Experts, brought in a red-footed robber fly that had been feeding on a brown marmorated stink bug. Adults perch on plants or other objects and catch their prey (wasps, bugs, bees, beetles, dragonflies and other flies) in midair. Larvae live in the soil and feed on organic matter and other insects such as white grubs and grasshopper eggs. Praying Mantids We have had quite a few praying mantids hanging out around the research center this year. A few have been on the perennial hibiscus which has a good infestation of brown marmorated stink bug so hopefully they are helping reduce the stink bug population. Today, there was a gravid female that we found feeding on a yellownecked caterpillar. It has plenty more larvae when it s ready for its next meal. Beneficial of the Week, Paula Shrewsbury Orangestriped caterpillar mummies Orangestriped oakworms, Anisota senatoria, are caterpillars that voraciously feed on red oaks (and hickory and birch) often causing significant defoliation leaving behind only the major leave veins. These caterpillars are in the family Saturniidae. Like many caterpillars we have discussed in the Note the ragged exit hole on the side of the orangestriped oakworm mummy where the new adult parasitioid chewed its way out of the caterpillar. Photo: Mike Raupp, UMD Cluster of orangestriped oakworm caterpillar mummies on tree branches indicate that a parasitic wasp has attacked and killed the caterpillars. Photo: Mike Raupp, UMD IPM Alert, oakworms are having an exceptionally good year. Having said this you should be aware that we are getting some help from naturally occurring biological control agents. The most common natural enemies of orangestriped oakworm are wasps or flies that parasitize the caterpillars. In particular ichneumonid wasps (Family Ichneumonidae) are common parasitoids of orangestriped oakworm. These wasps stab their ovipositor into the caterpillar and deposit an egg. The egg hatches and the wasp larvae consumes the caterpillar from the inside leaving behind just the shell or exoskeleton of the caterpillar. These shells are referred to caterpillar mummies. Many of you are familiar with the more common aphid mummies (aphids parasitized by wasps). 9

10 How can you tell if you are looking at the shed skin of the caterpillar left behind when it moults (grows) from one instar to the next, or a caterpillar mummy that is the remains of the parasitized caterpillar. First, examine the caterpillar closely and you will see the mummy has a ragged hole, often on the side, where the newly formed adult wasp chewed its way out of the caterpillar. Whereas, shed skins usually have a straight-line split on the top side of the caterpillar. Secondly, parasitized mummies usually remain on the branches of the tree and there will be a cluster of them since orangestriped oakworm are gregarious. Insect exoskeletons, the remains of normally developing caterpillars, do not remain on the branches of the tree. As I discussed last week there is often a lag time that it takes natural enemy populations to catch up with increasing herbivore populations. Hopefully by next season we will see signs of more caterpillar mummies and less damage than this year. For additional information on orange striped oakworm go to: (August 26, 2013) Weed of the Week, Chuck Schuster Japanese Knotweed, Polygonum cuspidatum, is a native of Eastern Asia that was introduced into the United States in the late 1800 s as an ornamental. It is an herbaceous perennial that grows in an upright shrub form, reaching heights of ten feet and more. This invasive perennial is found in landscapes, abandoned areas. It can tolerate full shade, high temperatures, salinity and even drought, but prefers moist sites. Leaves are arranged alternately on the stem, are five to six inches long and three to four inches wide. They are a broad oval or eggshape and have a pointed tip. Rhizomes that produce new plants help promote the thicket growing pattern of this plant. It is often relocated in contaminated soil. Stems, are hollow, jointed and when mature resemble bamboo. Each joint has a thin membranous sheath encircling the stem. Flowers are small and white in color, are found in clusters four to five inches in length, at the junction of the leaf petiole and the stem. Control can be obtained by grubbing out new plants, remembering that any portion of the rhizome left behind will generate a new plant. Cut stem applications work well in most temperatures unless the ground is frozen. Products that can be used include 25% glyphosate, Japanese knotweed triclopyr (Garlon) with a follow application on new seedlings. Foliar Photos: Ginny Rosenkranz, UME applications can be used for large areas using a 2% glyphosate or triclopyr with a surfactant. This method requires active growth and temperature above 65 F. Plant of the Week, Ginny Rosenkranz Many plants are chosen to create a solid evergreen hedge or barrier between properties, to provide privacy within a landscape or to screen out views that are unsightly. Ilex Mary Nell, grows into a pyramidal shape growing feet tall and 8-10 feet wide, with dark to medium shiny green leaves that grow 3-4 inches long with many short spines along the margin. The bright red, medium-sized berries grow in a spiral around the stems and stay on the holly through the fall and winter. Mary Nell hollies can have a central leader, but early pruning will create a dense framework of branches giving a tighter screen. Hardy from USDA zone 6-9, Mary Nell 10

11 grows best in full sun to partial shade. The soil should be rich and acidic with average to moist conditions, but the tree can handle some standing water. Mary Nell was created in Alabama from a cross between a Burford holly (I. cornuta Burfordii ) and a Red Delight (I. pernyi Red Delight )with the resulting plant crossed with Lusterleaf holly (Ilex latifolia) and named for the wife of Dr. McDaniel, former professor of Horticulture at the University of Illinois. Pests include scale insects, rot roots, leaf spot and stem cankers. Ilex Photo: Ginny Rosenkranz, UME Degree Days (As of Aug 29) Baltimore, MD (BWI) 2961 Dulles Airport 2971 Frostburg, MD 1889 Martinsburg, WV 2744 National Arboretum 3379 Reagan National 3379 Salisbury 3252 To check degree day (DD) accumulations in your local area go to: 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 Programs Go to for conference listings. 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.