TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers Commercial Horticulture April 25, 2014 In This Issue... - Ambrosia beetle update - Botrytis on peonies - Brown marmorated stink bugs - Gymnosporangium rusts - Apple scab update - Looking for images - Update on ash trees - Winter damage update - Eastern tent caterpillars - Euonymus leaf-notcher caterpillar - Indian wax scale - Scale on pine identified - Fertilizer Applicators Update - Boxwood mite and leafminer - Hollies looking bad - Pesticide drift Beneficial 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) 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) Ambrosia Beetle Update In our traps at the research center this week, there were only two Xyleborinus saxenii and no Xylosandrus germanus. We received a sample from Frederick collected on April 22 that did not have any ambrosia beetles present. There has been a significant drop in numbers over the last week. When temperatures rise again, beetle numbers in the traps will also increase. Continue to monitor the trunks of trees for wet spots and treat if needed. Preventing Peony Problems If your customers have peonies growing in their landscape you may be able to prevent problems later in the season. One of the major diseases of peonies is Botrytis that causes flower blooms to not open and shrivel on the stem. Now is the time of year to take action. Peony shoots are just pushing through the soil. Hopefully last fall you cleaned up the peony beds and removed all of the old debris which is where the fungus overwinters. The Botrytis fungus grows in the spring over new shoots of peonies and covers them with a dense, velvety-gray mold. It is worse when we have a wet spring. Very young shoots may be blighted early on and turn black if you do not take action. Botrytis may also grow on developing flower parts causing bud blast and flower blight. Infected buds may swell, and then die without ever opening. Flower infections can move down into the stem causing brown and tan, target-like discoloration. Infected petals which drop onto leaves can cause leaf spots.
During the growing season, very small, shiny black, somewhat sausage-shaped fungal structures called sclerotia may be found just under the epidermis at the base of infected shoots. If you missed the fall sanitation you can try to clean up as much of the leaf litter and old stems as possible this spring but you need to work fast. Commercial growers can treat the newly emerging shoots with either Serenade or Mancozeb by applying it as a soil drench to kill the sclerotia on the plant debris. Botrytis blight infects the foliage, buds and flowers of peonies Photos: Michelle Grabowski, University of Minnesota Extension - Horticulture, Bugwood.org Brown Marmorated Stink Bugs From April 12 through April 14 we observed increasing activity of adult brown marmorated stink bugs (BMSB) in office buildings and homes. The cold front blew in on April 15 through the April 17 and the stink bugs settled back into their hiding places in people s homes. With the warmer weather arriving we should see the overwintering adult stink bugs move outdoors onto plant material in the landscape and garden. We would be interested in hearing feedback from different parts of the state to see who is observing activity of the BMSB this spring. Send your information to Stanton Gill at sgill@umd.edu. Gymnosporangium Rusts (Cedar Apple, Cedar Hawthorn, and Cedar Quince Rusts) Tony Murdock, Fine Pruning, sent in a sample last week of red cedar from Walkersville that had gymnosporangium rust galls on it. Jessica Frakes, Thrive, Inc., also found the galls on cedar in Potomac on April 24. We have not seen or had reports of spore germination yet this season. Be sure to monitor galls closely after the rain moves through the area today. The gymnosporangium rusts require two kinds of plants to complete their life cycle. They overwinter on junipers such as the Easter red cedar as leaf galls or shoot cankers. In cool, wet periods in the spring these galls produce orange gelatinous tendrils upon which the teliospores are found. The teliospores germinate to produce colorless basidiospores. The basidiospores are carried on air currents to infect the pomaceous hosts (apple, Amelanchier, some pears). The orange gelatinous tendrils and infective teliospores will be produced on this gall when it absorbs water during rainy periods Cedar-apple rust is caused by the fungus: Gymnosporangium juniperi-virginiana. The fungus alternates between many species and varieties of cedar, (Juniperus species) and many pomaceous plants such as apple, pear and hawthorn. Leaf spots are produced on the pomaceous plants. 2
Cedar-hawthorn rust is caused by the fungus: Gymnosporangium globosum. Small galls are seen on the junipers, and leaf spots are seen on the pomaceous plants. Cedar-quince rust is caused by the fungus: Gymnosporangium clavipes. Shoot cankers are seen on the juniper and fruit and twigs are infected on the apples and hawthorns. This is considered the most destructive of the gymnosporangium rusts because of the damage to twigs and fruit. Control: Timing is critical for good control on the pomaceous hosts (apple, hawthorn, etc). The sprays have to be applied when spores are being shed from the junipers, usually starting in mid-march, but happening later this year due to the colder temperatures. No chemical control is usually advised to prevent infection of the junipers. Infection of the junipers is happening all summer and into the fall from spores produced on the apples which would require many sprays all season. The period during which the pomaceous plants are infected is short (from the start of the infection period through May). Spray susceptible crabapples, apples, quince and hawthorn with a labeled fungicide. Apple Scab Update from Penn State Extension The Penn State Extension disease update for April 22 reported, Apple scab spores continue to rapidly mature and discharge. Rain and thunderstorms are forecasted for Tuesday, April 22, 2014, and combined with temperatures in the upper 60s to low 70s, these are once again great conditions for scab infection. Apple cultivars with green tissue need to be protected. For more details, check out the Penn State Extension website. Do You Have Pictures of Your Employees Applying Pesticides Safely? Amy Brown is in need of slides or photos showing actual pesticide applicators making actual applications. Especially helpful would be shots showing applicators wearing protective equipment (PPE) for different types of applications everything from nothing special to full protection. This is for a slide set that will be used nationally/internationally. Amy will credit the slides and would appreciate knowing exactly how any donors would like them worded. Amy will edit out identifying characteristics like logos, company or place names, etc., and can also modify images to protect individual identity if necessary. Send in pictures for use at CMREC to sgill@umd.edu, and I will pass them along to Amy Brown. Thanks, Stanton How About the Ash Trees? Stanton Gill The western part of Maryland from the Chesapeake Bay to Garrett County is in a quarantine situation for emerald ash borer. The emerald ash borer has been found in Calvert, Anne Arundel, Howard, Frederick, Washington, Alleghany, Garrett, Prince George s, Montgomery, Charles and St. Mary s counties. We talked with experts from the mid-west who have had to deal with the dilemma of the emerald ash borer in the mid-west. They commented that you go through about 3 or 4 years of discovery of the pest in an area followed by a tidal wave of dying trees. We in Maryland are still in the discovery stage of this insect infestation. If your customers can keep a valuable ash tree alive through the tidal wave then the population goes down and you are hopefully left with standing trees. The questions are how much are you are willing to spend on protecting the ash trees and for how long? There is no natural resistance to the emerald ash borer among ash trees. Controlling insects feeding under bark of trees is very difficult. In university trials, they have found that treatments of some ash trees worked very well in some sites and the same treatment in other ash tree sites failed. Also, in some studies conducted over multiple years, Emerald ash borer densities continued to increase in individual trees despite annual treatment. Some arborists have combined treatments to increase the odds of success (e.g. combining a cover spray with a systemic treatment). It is best to inform a customer that this treatment is the best you can do and do not 3
guarantee control with insecticide treatments. Imidacloprid and dinotefuran should provide control for one season. Ash are wind pollinated and not pollinated by insects so applications of neonicotinoids should have no major impact on pollinators. Emamectin benzoate (Tree-age) provides control for 2 years (possibly into a 3rd year). Tree age is sold by Arbor-jet and must be trunk injected. Here is a list of chemicals with time of application and how long they will give control of the emerald ash borer: Table 1. Insecticide options for professionals and homeowners for controlling emerald ash borer that have been tested in multiple university trials. Some products may not be labeled for use in all states. Some of the listed products failed to protect ash trees when they were applied at labeled rates. Inclusion of a product in this table does not imply that it is endorsed by the authors or has been consistently effective for EAB control. This chart is in the publication Insecticide options for Protecting Ash Trees from Emerald Ash Borer at www.emeraldashborer.info/files/multistate_eab_insecticide_fact_sheet.pdf Insecticide Formulation Active Ingredient Application Method Recommended Timing Professional Use Products Merit (75WP, 75WSP, 2F) Imidacloprid Soil injection or drench Mid-fall or mid- to late spring XytectTM (2F, 75WSP) Imidacloprid Soil injection or drench Mid-fall or mid- to late spring IMA-jet Imidacloprid Trunk injection Early May to mid-june Imicide Imidacloprid Trunk injection Early May to mid-june TREE-ägeTM Emamectin benzoate Trunk injection Early May to mid-june Inject-A-Cide B Bidrin Trunk injection Early May to mid-june SafariTM (20 SG) Dinotefuran Systemic bark spray Early May to mid-june Astro Permethrin Preventive bark and foliage cover sprays Bayer Advanced TM Tree & Shrub Insect Control Winter Damage Update 2 applications at 4-week intervals; first spray should occur when black locust is blooming (early May in southern Ohio to early June in mid-michigan) Homeowner Formulation Imidacloprid Soil drench Mid-fall or mid- to late spring Crape Myrtles: We asked for feedback on crape myrtles this year. David C. Lindoerfer, owner of Inside Out Services, reported that four, 30-foot crape myrtles in Frederick County were killed back completely on the top of the plants. We will see if the roots put up new shoots. He also reports that crape myrtle plantings in Washington at his job sites look like they are leafing out this spring so damage may have been minimal in the immediate Washington D.C. area. Roses: Nick Weber, Rosarian in Olney, called to report that hybrid roses were severely injured in January and February of 2014. Many of the hybrid roses were killed to ground level. There was new growth coming out of the hybrid roses this spring, but the cold weather over the last two weeks has killed back this new growth. The bush type roses fared much better with less die-back than the hybrid roses. 4
Eastern Tent Caterpillars Eastern tent caterpillar egg hatch activity continues. Tony Murdock, Fine Pruning, found caterpillars that just hatched on crabapples in Frederick on April 18. The early instar caterpillars can be treated with with Bt, Conserve, Acelpyrn, or insecticidal soap at this point. A manual control option is to remove the tents when found in the crotch angles of branches. Euonymus Leaf-notcher Caterpillar Richard Chaffin, The Brickman Group, found late instar euonymus leaf-notcher caterpillars (Pryeria sinica) on Euonymus Manhattan in Baltimore on April 24. This caterpillar species has one generation and is active early in the season. In Maryland, it has been reported in Anne Arundel, Prince Georges and Baltimore counties. Control: Since the damage occurs early in the season, control is not always necessary. There is only one generation of this pest and plants can recoup. If you decide to treat, control options include Conserve (spinosad), Talstar (bifenthrin), and Orthene (acephate). Bt is effective only when the caterpillars are small. Euonymus leaf-notcher caterpillar on Euonymus Manhattan Photo: Richard Chaffin, The Brickman Group Indian Wax Scale Paul Thomas, Towson University, found Indian wax scale on winterberries, barberries, and knockout roses. Paul is sending us a sample so we can determine if this scale population survived the winter. The crawler stage for this scale occurs in early to mid-june in Maryland. An Indian wax scale infestation on winterberry Photo: Paul Thomas, Towson University Scale on Pine Identified Last week, we reported that Marie Rojas found an armored scale insect feeding on Japanese red pine that we have not seen recently in Maryland. It was feeding on the needles. We sent a sample to John Davidson for identificaton who identified it as pine oystershell scale, Lepidosaphes pini. It is considered an occassional pest. Pine oystershell scale was found by Marie Rojas on Japanese red pine 5
Professional Fertilizer Applicator Update By: Chuck Schuster, UME The season is in full swing. Things are getting done quickly, and soil tests are being utilized as a method of determining what needs to be applied to keep turf at its best. Often soil sample results come with recommendations for the application of nitrogen and phosphorus. Maryland regulations do not allow the use of these recommendations. While reviewing a recent soil test result, the phosphate level was in the optimum range, yet the recommendations called for.5 pounds of phosphate to be applied per 1000 square feet. For existing turf this would not be a good utilization of money as the turf does not need the additional nutrient, and an even bigger reason not to, it is in violation of the regulations that went into effect in October 2013.The soil test helps one make decisions on ph, and even K 2 O, but for nitrogen Maryland Turfgrass Professionals need to follow the University of Maryland recommendations and the MDA regulations. For existing turf, no phosphate can be applied unless the soil test results show that when converted to PFIV (using the chart in the back of the Turf Manaual) you are in the low or medium range. Phosphate may be applied when a new turf is established, but it must be incorporated into the soil. Following these rules will keep you in compliance with the Fertilizer Use Act of 2011. Boxwood Leafminer and Boxwood Mite By: Stanton Gill We received an email asking about using predators and parasites to control boxwood leafminers and boxwood mites. A better approach to deal with these two pests is using resistant varieties of boxwoods. Winter injury was a big deal in the winter of 2014 so selecting for the varieties with the least winter injury is not a bad idea. 2006-2007 Boxwood Evaluation: Here at the Central Maryland Research and Education Center, we have a planting of 15 different boxwood varieties to evaluate for winter injury and levels of leafminer and spider mite damage. Below are the 2006, 2007 combined ratings. Ratings: 0 = no damage, 1 = low damage; 10 = high damage Variety % Winter Injury % Leaf Miner % Spider Mite Common Boxwood 2.25 4.50 6.13 Elegantissima 3.88 4.50 6.38 Dee Runk 0.50 1.50 7.00 Wintergreen (big leaf) 0.63 4.50 4.75 Morris Dwarf 4.88 0.00 3.75 Vardar Valley 0.38 0.00 2.13 Justin Brouwers 2.00 7.30 4.67 Grace H. Phillips 4.00 1.13 1.50 Jensen 0.00 5.75 3.75 Green Pillow 3.50 1.63 4.25 Green Beauty 1.00 9.00 8.33 Fastigiata 0.00 0.75 8.13 Wintergreen (small leaf) 0.75 9.25 7.00 Insularis 0.63 0.88 4.88 Inglis 0.00 8.50 8.50 Saunders Brother s Nursery has experimented with about 85 varieties over several years and have found moderate to good resistance in these cultivars: Insularis Nana, Vardar Valley, Suffruticosa, Grace Hendricks Phillips, Morris Dwarf, Green Pillow, Golden Dream, Jim Stauffer, Wintergreen, Jensen, Winter Gem, Morris Midget, Rotundifolia, Elegantissima, Fastigiata, and Dee Runk 6
Hollies Looking Bad Now Looking Worse Soon We are getting in pictures of hollies with spotting on foliage. Some of the hollies include Burford holly, American holly, Chinese holly, and Koehneana hybrid hollies. The brown spotting and leaf scorching is making hollies really look bad at this time of year. In another couple of weeks they will drop the majority of this damaged foliage and the new foliage will emerge looking fresh and shiny. You do not have to do anything - just wait and the plants will, in most cases, look better in a couple of weeks. The winter weather was brutal on these plants. Hollies are not looking good in landscapes at this time of year Photo: Steve Clancy, Town Creek Landscaping Pesticide Drift By: Chuck Schuster, UME Pesticide drift has been one of very few things with which the turf and landscape industry seems to have problems. We work in areas where the public watches our work, some with an appreciation of what we are doing, others with a concern for the environment. The season has started off late this year, and everyone is pressing to catch up on herbicide applications for turf and landscapes. Be cautious with pressing to get all the jobs done on windy days, as this can be the first step in overstepping the rules for pesticide applications. This week there were several days with wind speeds above 10 mph, and yet applications did not stop. Last spring we had several sites with drift and volatilization related issues that resulted in plant damage. Take time to have your crews equipped with a wind speed meter so that they each applicator can determine when it is time to stop the application of products that may cause harm off-site. You do not want the problems of plant damage from drift because you felt it was more important to press on and get the job done even though wind speed was too high. Beneficial of the Week By: Paula Shrewsbury Ground beetles are abundant with lots of variation in how they look and what they eat. Ground beetles, often referred to as carabid beetles (family Carabidae), are common and abundant predators in our landscapes, nurseries, and in natural areas. Ground beetles get their name because most of them forage and live at the ground level. They are diverse in their appearance and in the food items on which they feed. There are over 40,000 known species world-wide of ground beetles. The predatory tiger beetles are also now included in the Carabidae family. Ground beetle species may be quite small at less than 1/8 in size, and others large at over 1 in size. They can range in color from black to metallic green. Most are shiny black and have ridged front wings. Their feeding habits are of interest from a pest management perspective. Some species of ground beetles are carnivorous, feeding mainly on prey (insects and mites), and generalists feeding on a diverse range of prey species. Other species of ground beetles are omnivores and feed on both prey and plant material (ex. weed seeds). Carnivorous and omnivorous species of ground beetles are predators of caterpillars, grubs, other species of beetles, fly maggots and pupae, aphids, weevils, earthworms, slugs, snails and other soft-bodied 7
creatures. There are also many species of ground beetles that are considered to be granivores and they mainly feed on seed, often weed seeds. They can be good biological control agents of weeds. One of my favorite ground beetles is the fiery searcher, Calosoma scrutator. The fiery searcher is a common predator in ornamental and turfgrass systems in addition to woods and fields. They can be found under decomposing wood, rocks, leaves, etc. They are active from around May all the way through November. Females lay eggs in soil. The larvae hatch out and begin hunting for prey. Adult beetles hunt for prey during the day usually by climbing and foraging on plants. Larvae also climb but usually hunt at night. If threatened by predators such as birds, snakes, lizards, frogs, and various animals, the fiery searcher releases a bad odor to deter the predator from eating it. Fiery searchers are known for eating caterpillars such as Eastern tent caterpillar (looks like they will have lots of food this year), gypsy moth caterpillars, and others. It would be hard to go wrong trying to encourage a diverse and abundant population of ground beetles with their potential for providing pest insect and weed suppression. A carabid ground beetle adult Photo: Joseph Berger, Bugwood.org The fiery searcher, Calosoma scrutator, is one of the largest carabid or ground beetles growing to 1.5 long. Photo: P. Shrewsbury, UMD Predators Get Eaten Marty Adams, Bartlett Tree Experts, brought in a Carolina praying mantid egg case with holes along the side. Eggs in this case have been eaten by parasitic wasps. The holes are exit holes for the wasps. 8
PLANT PLANT STAGE (Bud with color, LOCATION First bloom, Full bloom, First leaf) Amelanchier fernaldii Full bloom Silver Run (April 25) Asimina triloba First bloom Silver Run (April 25) Hydrastis canadensis First bloom Silver Run (April 25) Sassafras albidum Full bloom Ellicott City (April 21) Shortia galacifolia Full bloom Reisterstown (April 15) Spirea vanhouttei (bridal wreath spirea) Full bloom Ellicott City (April 21) Trillium catesbeyi Full bloom Silver Run (April 21) Degree Days (As of April 24) 2014 2013 2012 Baltimore, MD (BWI) 124 187 355 Dulles Airport 118 219 355 Frostburg, MD 53 107 178 Martinsburg, WV 136 195 329 National Arboretum 247 259 485 Reagan National 247 259 485 Salisbury 218 259 410 St. Mary s City 164 219 428 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. 9
Upcoming Conferences Maryland Arborist Assocation Pest Walk May 28, 2014 (afternoon to early evening) Location: Stevenson University Contact: MAA, 410-321-8082, office@mdarborist.com Procrastinators Pesticide Applicators Program June 6, 2014 Location: Montgomery County Extension Office, Derwood Contact: Chuck Schuster, 301-590-2807, cfs@umd. edu Procrastinators Pesticide Applicators Program - Eastern Shore June 13, 2014 Location: Wye Research and Education Center, Queenstown, MD Contact: Ginny Rosenkranz, 410-849-6141, rosnkrnz@umd.edu MGGA Field Day June 19, 2014 (afternoon through early evening) Location: Tidal Creek Growers, Davidsonville, MD MNLA Field Day June 26, 2014 Location: Roseland Nurseries, Sudlersville, MD Maryland Christmas Tree Association Summer Meeting June 28, 2014 Location: Gaver Tree Farm, 5501 Detrick Road, Mt. Airy, MD 21771 Contact:301-865-3515 or gavertreefarm@aol.com Greenhouse Biocontrol Conference August 6, 2014 Location: Maritime Institute, Linthicum, MD 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 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.