TPM/IPM Weekly Report

Transcription

1 TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers Commercial Horticulture May 11, 2012 In This Issue... - Birch dieback - A new IPM app - Columbine leafminer - Lesser peachtree borer and lilac borer - Azalea leaf gall - Lecanium scale - Cankerworm activity - Brown marmorated stink bugs - Tick activity - Honeylocust plant bugs - Giant bark aphids and other aphids - Diseases on roses - Spangled oak gall - Azalea lace bug - Phlox plant bug - 17 year cicada - Brood I (Virginia) - Anthracnose - Aphids on lamb s ear - Bagworms - Japanese maple scale - Gloomy scale - Dusky birch sawfly - Growing degree days Weed of the Week Plant of the Week Degree Days Phenology Conferences Integrated Pest Management for Commercial Horticulture 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 (office) or (cell) Regular Contributors: Pest and Beneficial Insect Information: Stanton Gill and Paula Shrewsbury (Extension Specialists) and Brian Clark (Extension Educator, Prince George s County) 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) Birch Dieback In response to last week s request to find out if others are seeing any dieback on birch, here are responses we received: Todd Tarring, Pleasant Valley Landscapes: We are experiencing birch tree dieback on a commercial job site where the trees were planted over the winter months (not last fall). They leafed out nicely early this year only to drop leaves and it appears that they won t re-leaf and they have a lot of dead wood. We will probably have to replace them. We don t see any obvious insect or disease problems and thought they were getting adequate moisture. Maybe they got dry at some point this spring, but we really are baffled by this as they looked great when they initially leafed out this spring. We have also seen dieback in general on other birch trees planted on this site over the past 1-3 years. We also had issues with birch trees thinning out and dieback on birch trees in our nursery this spring. This may be due to dry conditions though. Rob Meier, Montgomery Village: We had some installed last fall that are not doing very well. A New IPM App - Coming Soon A new app is close to release through Apple and Android. It is called IPM Pro and was developed by Extension specialists in various states. It puts major pest and cultural practices information at your finger tips and provides automatic text-like alerts for time-sensitive pest issues and cultural practices -alert date adjusted specifically for your location. It also contains images, pest life cycles, and management options for major pests of woody plants. Go to to find out more!

2 Columbine Leafminer Brian Scheck, Maxalea, Inc., reported columbine leafminer damage on columbine this week in Baltimore. Look for the serpentine trails on the foliage that are created by the fly larvae feeding within the leaf. This leafminer overwinters in the pupal stage. It emerges as an adult in the spring and lays eggs at about the same time the plant starts to flower. More than one leafminer may be present within a leaf. Control: In most landscapes it is probably not worth trying to control this leafminer. The damage is noticeable, but usually the plant survives. For commercial herbaceous perennial nurseries where they want to sell really clean plants then imidacloprid can be used to treat the plant or Avid, or Tristar. Applications need to be applied before the leafminers show up in the foliage. Damage from columbine leafminer Photo: Brian Scheck, Maxalea, Inc. Lesser Peachtree Borer and Lilac Borer Adult male lesser peachtree borers are showing up in baited pheromone traps in Westminster. The first one was detected on Sunday May 6th. Adult lilac borers also continue to be caught in the trap this week. Control: Apply Permethrin or bifenthrin to the trunks of susceptible trees. The best thing to do that is nonchemical in orientation is to keep the susceptible trees growing vigorously and avoid wounding during the growing season. For more details on lesser peachtree borer - go to Azalea Leaf Gall In recent reports, we have covered the camellia leaf gall. This week, Brian Scheck sent in a photo of a similar leaf gall that develops on azalea and is caused by the fungal pathogen, Exobasidium vaccinii. The symptoms start as swollen tissue on newly expanding leaves, shoots, buds or flowers. A white surface growth that contains the reproductive spores develops on these galls. The galls range in color from green to pink to red depending on the part of the plant infected. Eventually these galls turn brown and harden. They are not a serious problem on azaleas. Fungicides are not effective. It is best to hand pick galls before the white growth develops to reduce the incidence of this disease next season. Lecanium Scale on Willow Oak Damian Varga, Scientific Plant Service, brought in lecanium scale on willow oak on May 8 from Odenton. The females are swollen and loaded with eggs. They look really close to the crawler stage. Control: Talus or Distance will control this scale. Dinotefuran or Imidacloprid applied as a soil drench will also work. Early stage of the gall is green. Photo: Brian Scheck, Maxalea, Inc. Lecanium scale on willow oak stem (left) and female cover showing eggs underneath (right) 2

3 Cankerworm Activity We received the following reports about cankerworm activity in 2012: Richard Shaw, Davey Tree Experts: We had an infestation of cankerworm on red maples on a property on Wye Island. They completely defoliated about 30 trees in a matter of 7 days. Bob Tatman, Maryland Department of Agriculture: Bob sent a map showing defoliation by spring cankerworm ( I flew over the area of Southern Maryland on April 24, There is some defoliation in Charles and St. Mary s counties. Ben Beale, UME-St. Mary s County: There are patches of defoliation from cankerworm in Charles County on 301 between La Plata and The Harry Nice Bridge and proceeding south on 234 into St. Mary s County. In some areas the defoliation affects acre woodlots. I noticed some the trees in my yard (St. Mary s County) are affected as well and have received some calls from areas north of Waldorf, so it appears the damage may be a little more widespread in lower southern Maryland. Norm Brady, Bartlett Tree Experts: We have had cankerworm feeding on oaks in Princess Anne and Talbot Counties for about 2 weeks. Populations are not heavy. Karen Boswell: There are a lot of trees defoliated in St. Mary s County from cankerworms. Brown Marmorated Stink Bugs Adult females are very active in landscapes and orchards this week. We are picking up a lot in black and blue light traps this week. Females should start laying egg masses sometime shortly. If you find egg laying please send me (Stanton) an at sgill@umd.edu. Newly hatched brown marmorated stink bug nymphs by egg mass (2011 photo) Ticks Here are the responses we received on tick sightings this year: Tom Robertson, Carroll County: As a forester, I spend a lot of time in the woods and started noticing sometime last October that I was not finding any ticks on me even after spending full days in woods full of deer. This past weekend I found the first tick of the year. Generally by now I have picked off several dozens of ticks. Wade Dorsey, DNR: In Garrett County I am seeing and hearing reports of more ticks than usual. Matt Berres, Greenbelt Homes Inc.: I have been seeing deer and dog ticks in Greenbelt MD and elsewhere in Prince George s county for the past 6 weeks. It is hard to quantify if levels are higher or lower than previous years but they are definitely around. George Eberling, Maryland Forest Service: There has been no reduction in ticks so far this year in WA and AL counties. Deer ticks started coming out in early February and were very prevalent in March. Dog ticks have been heavy about the last 3 weeks to a month was the worst year for ticks, both types, I ve ever experienced in my life. 3

4 Honeylocust Plant Bug Steve Sullivan, The Brickman Group, sent photos of a honeylocust in northern Virginia on May 4 that are about 30 feet tall that were completely scorched from plant bug. He noted that they were swarming on the tree like nothing he has ever seen! Close-up of plant bug damage and defoliated tree due to plant bugs Photos: Steve Sullivan, The Brickman Group Giant Bark Aphids Giant bark aphids are the largest aphids that occur in the United States. This week they were found on the trunks of beech trees. Look for the grayish aphids that cluster in groups on trunks. Aphid populations tend to be highest in late summer. Giant bark aphids found on trunk of beech More Aphids: Will Lowery, Salisbury University, has been seeing a lot more aphids this year compared to last year, primarily on roses. He noted that he has not noticed any ladybird beetles yet. While scouting this week, Marie Rojas, IPM Scout, found young assassin bug nymphs feeding on witchhazel gall aphids rolled in a hawthorn leaf. Diseases on Roses Will Lowery is also reporting that he has one clump of Knockout roses that have been attacked by powdery mildew that he is having a tough time getting rid of because of the weather. Steve Sullivan saw some black spot on some shrub roses (not Knockouts) this week. Spangled Gall on Oak Another gall found this week is spangled gall starting to develop on oak in Wheaton. This cup-shaped gall is caused by a cynipid wasp. Control is not necessary. Spangled gall just starting to develop on oak 4

5 Azalea Lace Bug Activity Azalea lace bugs are finishing up their first generation of activity. There are four generations a year in Maryland. Eggs overwinter inserted in plant tissue. Monitoring: Look for yellow stippling of new foliage on azaleas. Look on the underside of foliage for nymphs, adults, and black fecal spots. Control: Get good coverage of horticultural oil on the underside of foliage to reduce populations. Applications of imidacloprid and other labeled neonicotinoids can be used. Many products are labeled for lace bugs. Azalea lace bug damage Phlox Plant Bug Phlox plant bug is very active on phlox in the landscape in Wheaton this week. These bugs use their stylets to pierce plant tissue and extract plant juices. Look for the yellow stippling and distorted foliage Phlox plant bug adult Heavy phlox plant bug on foliage caused by this feeding. The feeding by this plant bug can stunt plants. Control: For control of this plant bug in the landscape, options include Orthene, Astro, or insecticidal soap. The eggs are inserted into the plant tissue by the fall so cutting and removing dead plant stalks helps reduce the population for the following season. Phlox plant bug nymphs 17 Year Cicada - Brood I From: Eric Day, Virginia Tech Just an FYI, here in Western Virginia, we are experiencing Brood I of the 17 year cicada. It is one of the smallest broods, but it has also caused the emergence of periodical reporters (paper, video, and audio). Also occurs in West Virginia and likely Maryland, interestingly the map also shows Long Island, NY. See and 5

6 Anthracnose in Shade Trees Spring is the season for anthracnose diseases in shade trees. Anthracnose diseases are caused by a group of related fungi that induce similar leaf lesions and/or twig dieback on a number of woody plants. Anthracnose diseases are common on sycamore, white oak, maple, ash, walnut and dogwood. Each tree species is infected by a specific anthracnose fungus, so the disease does not spread between different types of trees. All anthracnose diseases are favored by cool, wet spring weather, so it may seem as if the disease is spreading through entire landscapes. The characteristic symptoms of anthracnose diseases are brown or tan lesions that are commonly found along leaf veins. Several lesions may coalesce and kill the entire leaf. Young leaves become distorted as healthy areas of the leaf continue to grow and expand around dead areas. Trees may lose a large number of leaves in the spring or early summer when weather conditions are optimum for disease development. A second flush of growth results in new Anthracnose symptoms on sycamore foliage to replace leaves lost to anthracnose, and by mid summer trees appear normal. With sycamore anthracnose, the infection moves from leaves into small twigs, causing cankers and twig dieback. This disease is responsible for the angular branching pattern of the species. Management strategies: Although disease symptoms can be very noticeable, anthracnose rarely has a negative impact Anthracnose on London planetree on the health of mature trees. Maintaining the health and Photos: Steve Sullivan, The Brickman Group vigor of commonly infected trees through cultural practices (irrigation during dry weather, avoiding root injury from construction, etc.) is important in managing the disease. Dead twigs can be pruned during the winter or dry summer months. Mature trees can be thinned for better air circulation throughout the canopy, decreasing leaf wetness and thereby reducing fungal infection. Rake and remove infected leaves in the fall and plant resistant varieties when available. Oriental plane and certain cultivars of London plane (such as Liberty and Columbia ) are more resistant to anthracnose than American sycamore. Young trees in nurseries or small, newly planted trees may Anthracnose on oak benefit from fungicide sprays to prevent excessive leaf loss. Sprays must be applied at or before bud break, before infection has occurred, and repeated according to label directions. Some fungicides registered for anthracnose control include chlorothalonil, certain copper products, and mancozeb. Check product labels tree species and rate information. For managing anthracnose in large, high-value sycamore trees, products labeled for trunk injection include Arbotect 20S and Alamo (late summer/early fall injection for managing disease the following year), and Fungisol (spring application only). Consult label for specific instructions. 6

7 Aphids on Lamb s Ear Aphids are causing extensive yellowing on the foliage of lamb s ear (Stachys byzantina) in the landscape. Control: Be sure to check for predator activity on these plants. Monitor aphid populations to determine if control is necessary. Control materials include insecticidal soap and horticultural oil. Consult the Extension perennial manual at grnhs_pubs.htm for additional options. Chlorotic foliage on lamb s ear foliage caused by aphid feeding (left) and a close-up of the aphids on the underside of the foliage Bagworms Damian Varga, Plant Scientific Service, reported bagworm activity on Leyland cypress in Fulton on May 10. Control: If the larvae are still small, Bt can be used. For later instars, options inlcude Acelpryn, Confirm, and Conserve. Japanese Maple Scale Update Japanese maple scale (JMS) continues to be monitored closely on maples in College Park, MD. As in the last few weeks, we continued to see adult females with eggs, but NO crawlers as of yet. The degree day monitor we have on campus reports 693 DD (Jan. 1 May 8). Weather.com reports 680 DD for College Park. Data based on 3 years of JMS studies indicate 1st generation crawler activity should start around 815 DD (base 50 F, start date Jan. 1). Remember DD are guidelines that tell you when you should be more intensely monitoring your insects and plants. There are areas of MD that are cooler than College Park (i.e. have fewer DD accumulated) and they are seeing adult female JMS but females have not developed eggs yet. For more information on JMS see our UME Fact Sheet at: or an IPM webinar on JMS at: Gloomy Scale Steve Sullivan found a heavy infestation of gloomy scale on red maple in Anne Arundel County this week. Heavy infestations can cause dieback of terminal growth. Usually, the crawlers are active in Maryland in June, but this year look for them a bit earlier. Control: A mixture of 0.5-1% horticultural oil and pyriproxyfen (Distance) or buprofezin (Talus) could be used on small trees. Dinotefuran (Safari, Transtect) applied as a soil drench may control this pest. Gloomy scale on maple Photo: Steve Sullivan, The Brickman Group 7

8 Dusky Birch Sawfly Dusky birch sawflies were active on river birch in Columbia this week. The larvae line up around the margin of a leaf when feeding. They become s-shaped when disturbed. This sawfly has two generations per year in Maryland (April and May and then again in July through early fall). Control: Infested branches / leaves could be pruned off. If populations are too high for mechanical removal, spinosyn (Conserve) can be applied. Growing Degree Days: Why and How to Use Them and Where to Find Them Paula Shrewsbury Insects (and mites are included) are cold blooded organisms and therefore their development rate is directly related to temperature as temperatures get warmer insects develop faster. In addition, most insects have a lower and upper temperature development threshold, below or above which, respectively, they do not develop. Growing degree days (GDD or DD) are a measure of the heat units (= related to temperature and the amount of time per day that an insect spends actively growing) that accumulate over time. Therefore, by keeping track of the number of DD that accumulate over time we can predict activity of different insects and their susceptible life stage(s) (= target life stage for control measures). For example, when crawler activity of a specific scale insect is likely to occur could be predicted. There are a few factors to consider in using this method. First, research must be conducted to identify what the DD accumulations are for all the various insects and their susceptible life stage(s). These are known for some key pests but not all (we try to provide this information in the newsletter). Second, temperatures can be quite variable within a state, region, and even among the varying microclimates within a single landscape or nursery so DD accumulations may vary. Third, there is some variation in how DD are calculated. Some DD are calculated using what is referred to as integral temperatures (ex. using temperature readings taken every hour of the day/night) and others use only the minimum and maximum temperature for the day (somewhat less accurate). Most DD calculations use a default lower development threshold for insects of 50 F even though not all insects stop developing below this temperature. For logistical reasons this standard threshold method is easiest. All of these factors leave room for error or variation in DD calculations and predictions. What these factors tell us is that DD information should be used as a guideline to predict when target life stages are active, BUT you still need to monitor the insects for activity and their life stage on the plants in the location you are managing. Where can you find / how do you get DD accumulation data? There are several brands of technology that can be purchased and placed in a specific location that record temperature and calculate DD. We do this in our research and have used temperature monitors made by Hobo and Watch Dog, but there are others too (no specific endorsement meant here). DD accumulations are reported in various extension publications (ex. this IPM Alert). Weather data can be accessed from various sources (NOAA, Underground Weather, Weather Channel) which provide DD or the temperature data that allows you to calculate DD. In the IPM Alert Newsletters we have been using weather data from NOAA. However, in the future we will be reporting DD accumulations accessed from the Weather Channel web site. Why? The DD data from both sites vary relatively little from each other (Suzanne Klick made comparisons for the last 3 years thanks); and DD data from weather.com is easily accessible and available for many locations. For example, if we are reporting 8

9 Japanese maple scale 1st generation crawler activity is predicted to occur around 815 DD, you can put your location into weather.com and find the DD accumulations for your specific area. How do you access DD information using weather.com? Go to: Select from top menu bar weather Select from menu bar farming Select Growing Degree Days calculator from the box on left (Farmers Forecast) Enter location and other information OR go to: Wow that is a lot of information. If you have questions or comments feel free to me at pshrewsbury@umd.edu Weed of the Week, Chuck Schuster Coming from questions and samples from Washington County, our weed of the week is sulfur cinquefoil, Potentilla recta. This is a perennial weed found throughout the United States, often in roadside edges, pastures and in agronomic crops. Its is native to the eastern Mediterranean region of Eurasia. Reaching a total height of two and one half feet, it will present in the early stages emerging from a crown. Leaves will most often be divided into seven leaflets, though it will occur with both five and nine leaflets on occasion. These leaflets will originate from a common point on the stem. Lower leaves are alternate and occur on petioles. All leaves are longer than they are wide and have sparse hairs, a coarse toothed margin and are widest in the middle of the length of the leaflet. This plant is tolerant of many different soil moisture conditions and attempts to create a dense monoculture. The flower is yellow with a darker yellow center, up to one inch in diameter, and has five notched petals. Occurring with a taproot root system, this plant should not be difficult to identify. It is similar to oldfield cinquefoil and common cinquefoil, but can be distinguished by the seven leaflets and the flower with five petals. Both common and oldfield cinquefoil only have five leaflets. Control of sulfur cinquefoil can be accomplished in turf using most post emergent broadleaf weed control products that contain 2, 4D. Glyphosate products are effective in areas that desirable plant material does not exist, and roots / trunks will not be exposed. Dicamba in open areas mixed with 2, 4D has been shown to increase the effectiveness of the 2, 4D. Sulfur cinquefoil Photos: Chuck Schuster, UME 9

10 Plant of the Week, Ginny Rosenkranz Lamium maculatum Beacon Silver, or spotted dead nettle, has a square stem that places it in the mint family, It loves moist rich soils and afternoon shade. The plants are semi-evergreen, with silver leaves surrounded by dark green margins. Beacon Silver grows 6-12 high and creates a dense mound that spreads into a groundcover. More cold tolerant than heat tolerant, Lamium maculatum grow in USDA zones 3-8, but often has a difficult time recovering from the heat of summer in the warmer regions and is not drought tolerant at all. The plants have been listed as both deer and rabbit resistant, although that depends on the number and pressure of deer and rabbits in the area. Mid spring to early summer and often again in the cooler temperatures of fall, Beacon Silver plants produce tiny pink to purple hooded flowers at the terminal of each plant, creating umbrellas of color among the silver and green sea of leaves. An excellent groundcover for shady moist areas, Beacon Silver can also be used as an edging plant and as a cascading feature in a mixed container. Soil ph of 7 or higher is preferred so lime should be added to raise the ph level. The plants can be sheared after flowering to maintain compact growth. When conditions are moist, slugs and snails are the most frequent pests along with foliar leaf spots and root rot. Educational Resources: Posters Mary Kay Malinoski, Home and Garden Information Center, has updated all of their downloadable posters so that they can be previewed prior to downloading the files. Available posters include 8 on sustainable lawn care and 15 expert plant picks for diversifying landscapes. Five new pest posters have been added: brown marmorated stink bug, mosquitoes, rats, spiders, and stinging insects. Go to for the posters and previews. Degree Days (As of May 10)* Baltimore, MD (BWI) 538 Dulles Airport 548 Frostburg, MD 305 Martinsburg, WV 519 National Arboretum 710 Reagan National 710 Salisbury 600 Lamium Beacon Silver Photos: Ginny Rosenkranz, UME *As of today, degree day calculations are now from weather.com growing degree day calculations instead of NOAA min and max temperatures. 10

11 Plant Phenology: What s in bloom PLANT PLANT STAGE (Bud with color, First LOCATION bloom, Full bloom, First leaf) Amsonia Blue Ice Bud with color (May 8) Silver Run Amsonia hubrichtii First bloom (May 8) Silver Run Clematis Westerplatte Full bloom (May 2) Silver Run Iris pseudacorus Full bloom (May 7) Ellicott City Kalmia angustifilia Royal Dwarf Full bloom (May 8) Silver Run Kalmia latifolia Little Linda Bud with color (May 8) Silver Run Maienthemum canadense Full bloom (May 8) Silver Run Magnolia tripetala Full bloom (May 8) Silver Run Rhododendron Home Bush Full bloom (May 8) Silver Run Rhododendron Marydel Rhododendron nudiflorum Full bloom (May 8) Silver Run Rhus toxidendron (poison ivy) First bloom (May 6) Ridgely Scutellaria serrata Bud with color (May 8) Silver Run Sophora davidii Full bloom (May 8) Silver Run Trillium flexipes and Trillium luteum Full bloom (May 8) Silver Run Tradescantia virginiana First bloom (May 8) Ellicott City 11

12 Upcoming Programs MAA Pest Walk May 17, 2012 Location: Brookside Gardens, Wheaton, MD Invasive Species Identification and Management Seminar May 23, :30-3:15 Location: Government Center Parkway, Fairfax, VA Cost: Free, but registration is required. To register please go to: Contact: Jack Baggett , fairfaxcounty.gov ASCFG Mid-Atlantic Regional Meeting June 18, 2012 Roost Flowers and Design Location: Virginia Beach, Virginia ascfg.org 2012 Perennial Plant Symposium July 4-10, 2012 Location: Boston, Massachusetts perennialplant.org OFA Short Course July 14-17, 2012 Location: Columbus, Ohio ofa.org OFA Perennial Production Conference September 10-12, 2012 Location: Grand Rapids, Michigan ofa.org MNLA Field Day June 21, 2012 Location: D.R. Snell Nursery, Union Bridge, MD Maryland Christmas Tree Association s Summer Meeting June 30, 2012 (Saturday) Location: Taylor Sines Woodlake Tree Farm, Oakland, MD Contact: 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 Ginny Rosenkranz Extension Educator rosenkrnz@umd.edu David Clement Plant Pathologist hgic.umd.edu Andrew Ristvey Extension Specialist aristvey@umd.edu Brian Clark Extension Educator bpclark@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.