Inspector Findings in ----Kentucky---- Volume VI Issue 1 University of Kentucky - Department of Entomology April 2002

Transcription

1 Inspector Findings in ----Kentucky---- Volume VI Issue 1 University of Kentucky - Department of Entomology April 2002 JOE COLLINS -NURSERY INSPECTORS- CARL HARPER Left: Hemlock wooly adelgid on branches Top: Close up of hemlock wooly masses Middle: eggs of hemlock wooly adelgid Bottom: Distribution map

2 Hemlock Wooly Adelgid Revised by: Latif Lighari, Extension Educator, Agriculture; Edmond L. Marrotte, Consumer Horticulturist; Originally written by: Latif Lighari and Roger Adams, IPM Coordinator University of Connecticut The hemlock woolly adelgid (HWA) is a serious pest of Canadian hemlock, Tsuga canadensis, in the northeastern states. This insect was discovered in Connecticut in 1985 and has spread rapidly to both cultivated and forest hemlocks. Adelgids are small, soft-bodied insects that are closely related to aphids. They have piercing-sucking mouth parts, which are inserted to remove plant sap for food. The HWA feeds primarily on young branches causing cessation of tree growth, discoloration and premature drop of needles, the dieback of branches and possible death of the tree in as little as one year. Description and Life History The females are oval, blackish-grey, about 2mm in length and serve as the overwintering stage. The brownishorange, very small, oblong eggs are laid in cottony white egg sacs (about 50 eggs per sac) on young twigs from late march to May. The presence of the egg sacs offers the most visible diagnostic evidence of an HWA infestation. The eggs hatch into reddish-brown crawlers (nymphs) from early April through early June and begin feeding on the sap of young twigs, maturing into adults in a few weeks. Some of the adults are wingless and remain on hemlock for a second generation, while the winged forms may fly to nearby hemlocks or spruces. None of the common native and exotic spruces appear to be suitable hosts for the winged HWA to complete its life cycle. Second generation crawlers initially feed on new twigs during July but become dormant in late summer through early autumn. Crawlers resume feeding in mid- October and develop into the overwintering adults. Pest Management and Control Infestations of the HWA can be detected early by periodically examining young twigs for the presence of the egg sacs. They are readily observed in the spring before the eggs have hatched. Keep in mind that remnants of old egg sacs may remain on twigs long after the eggs have hatched and the insect has been controlled. Early detection is very important because injury to hemlock may develop quickly. That is why periodic examinations are an important practice in the control of the HWA. Several insecticides are available that will provide excellent HWA control. Insecticides should not be applied on a preventive basis. Many of the hemlocks in Connecticut will not be infested and will not need treating. Controls should be applied only when HWA infestations are observed. An excellent time to control an HWA infestation is from July through September after the eggs have hatched and the young adelgids are relatively unprotected. Summer oil and insecticidal soap have been found to provide excellent control with one application, provided complete coverage is made in this time period. Both insecticides kill only by direct contact. Thorough coverage with a drenching spray is essential for control. Dormant oil is effective for HWA control when applied in April to mid-may. It will also control scale insects and mites at the same time. Other insecticides capable of controlling HWA include acephate, dimethoate and malathion. Thorough coverage of the insect is essential for effective management. More than one application may be needed for effective control where it is difficult to achieve complete coverage of the plant. Unfortunately, natural enemies, such as disease, parasites and predators, have not been numerous enough to achieve significant management, but they may offer hope in the future. Sudden Oak Death Quarantine Announced by John Hartman, Extension Plant Pathologist During the past year, a new disease of oaks and other woody plants has appeared in the coastal regions of northern California and Oregon (see insert). The disease, sudden oak death (SOD), is caused by a fungus new to the U.S., called Phytophthora ramorum. The fungus causes a bleeding necrosis on the trunks and limbs of affected trees and shrubs and can girdle and kill infected plant parts. In Kentucky, our concern has been whether or not this disease would be similarly devastating if the pathogen were introduced into the state. The SOD disease fungus thrives in the relatively cool and moist climate of coastal California and Oregon. Since we also can have periods of cool, moist weather in spring and sometimes in fall, one might expect the disease to sometimes thrive here, too. Thus, there is a need for a quarantine to prevent movement of infected plants or the pathogen from the West Coast to Kentucky. Effective February 14, 2002 the USDA Animal Plant Health Inspection Service (APHIS) publis hed an interim rule and notice of public hearings on quarantine and regulations for Phytophthora ramorum, cause of Sudden Oak Death. The full text of this interim rule appears in the Federal Register, Volume 67, Number 31, p The regulations quarantine ten counties in California and a portion of one county in Oregon because of the presence of P. ramorum and restrict the interstate

3 movement of regulated and restricted articles from quarantined areas. Regulated articles may be moved interstate from quarantined areas under certificates issued by APHIS PPQ inspectors. Reminder On Status Of Diazinon, Chlorpyrifos (Dursban) On December 5, 2000, EPA announced an agreement to phase-out diazinon, one of the most widely used pesticides in the United States, for indoor uses, beginning in March 2001, and for all lawn, garden and turf uses by December Specifically, the terms of the agreement implement the following phase-out schedules: _ For the indoor household use, the registration will be canceled on March 2001, and all retail sales will stop by December _ For all lawn, garden and turf uses, manufacturing stops in June 2003; all sales and distribution to retailers ends in August Further, the company will implement a product recovery program in 2004 to complete the phase out of the product. _ Additionally, as part of the phase out, for all lawn, garden, and turf uses, the agreement reduces the manufacturing amounts. Specifically, for 2002, there will be a 25 percent decrease in production; and for 2003, there will be a 50 percent decrease. Also, the agreement begins the process to cancel around 20 different uses on food crops. Chlorpyrifos (Dursban) It is legal to purchase and use chlorpyrifos products according to label directions and precautions. Use of these products according to label directions does not pose an imminent hazard. Consumers should know that the EPA took this action to protect children. Consumers who choose to use the product should take special care to always read and follow the label precautions and directions. If consumers choose to discontinue use, they should contact their state or local hazardous waste disposal program or the local solid waste collection service for information on proper disposal. Dursban - Changes to residential uses (home, lawn and garden uses as well as uses in schools, parks, daycare centers, and commercial buildings, except limited public health uses) Cancel and phase out nearly all indoor and outdoor residential uses to effectively eliminate the use of Dursban (chlorpyrifos) by homeowners, limiting use to certified, professional, or agricultural applicators. Those uses that pose the most immediate risks to children will be canceled first, including home lawn, indoor crack and crevice treatments, and whole-house postconstruction termiticide treatments. Cancel uses in schools, parks, and other settings where children may be exposed. Sale of products for these uses listed above will end 12/31/01. Over the next several years, remaining uses, including spot and local termiticide treatments and preconstruction termiticide applications, will be phased out. Gypsy Moth The European Gypsy Moth was deliberately introduced from Europe at Medford, Mass. in 1868 or 1869 by Leopold Trouvelot (he made a living as an artist, painting mostly portraits, but he had an amateur interest in entomology). Trouvelot hoped to raise this moth for silk production. Unfortunately, some of his moths escaped. Trouvelot understood the potential magnitude of this accident and notified local entomologists but no action was taken. By 1889 the Gypsy Moth was doing heavy damage in certain parts of the Boston area; it is now a serious pest throughout much of the Northeast and is expanding its range. As a caterpillar, the gypsy moth has a voracious appetite and has been known to completely defoliate forests. The caterpillars feed on about 500 different species of plants. The most preferred host is oak followed by apple, cherry, hawthorn, hickory, maples, sassafras, sweet gum and willow. Only the caterpillar stage feeds. When fully grown, the caterpillar is about 2 inches long, very hairy and has five pairs of blue dots followed by six pairs of red dots along its back. The larval stage lasts about seven weeks. Gypsy moths are spread in two different ways. Natural spread occurs when newly hatched larvae are dispersed by blowing wind. Over the past years, gypsy moths have moved long distances on outdoor household articles such as cars and recreational vehicles, firewood and other items. It has been estimated that 85% of new infestations have been through the movement of outdoor household articles. Once established, gypsy moth numbers can fluctuate widely from year to year. Seasons with light damage can be followed by seasons with severe damage. In periods of heavy outbreaks, gypsy moth caterpillars crawl on walls, across roads, over outdoor furniture, and sometimes will come inside homes. The gypsy moth has four different life stages: egg, caterpillar, pupa and adult moth. The female moth lays eggs in masses which will contain between 500 and 1,000

4 eggs and will have a fuzzy tan appearance. The eggs hatch in early spring, coinciding with the bud break of most hardwood trees. Gypsy Moth Numbers for Kentucky Since 1986, survey work in Kentucky has been accomplished using the national protocol of one pheromone trap per four square miles in rural areas; one trap per square mile in urban areas and special sites. These traps use a synthetic pheromone that mimics the sex attractant a female moth releases to attract a male moth. This pheromone can attract a male moth from over 1 mile in certain conditions. Although the state consists of 70% hardwoods and is in close proximity to infested areas, poor funding levels have enabled us to trap about one-third of the state in most years. A significant increase was realized in 1997 enabling us to survey more of the state each year. Activities dealing with the European Gypsy Moth Over 7,000 pheromone traps were set out in These traps were placed in the eastern part of Kentucky and the area surrounding the Land Between the Lakes(LBL)area in Western Kentucky. This trapping was done in conjunction with USDA-APHIS and the Kentucky Division of Forestry to locate any gypsy moths that may have entered the state. Kentucky is also participating in the Slow the Spread Project (a joint venture between 9 states with gypsy moth that uses mass trapping to slow the rate of spread). A total of 115 moths were trapped in Areas where moths were captured will be trapped again next year at a higher density. Boxwood Psyllid The boxwood psyllid, Psylla buxi, causes a characteristic cupping of the leaves on the terminal and lateral buds of boxwood. This insect can overwinter as an egg, or as a first instar nymph under the bud scales. As the buds develop in the spring, the eggs hatch and nymphs emerge to infest the leaves. The feeding causes the leaves to curl and form a cup which encloses the greenish colored nymphs. The nymphs produce a white, waxy secretion which may cover part of the body or small waxy pellets beside the nymphs. The greenish adults emerge late May into June, mate and lay eggs under the bud scales. Only one generation occurs each year. This pest causes aesthetic damage to American boxwood and English boxwood. Control: Adults may be controlled by a registered residual insecticide in late May into June. Sprays are only necessary if infestations are heavy. Eggs hatch around 80 growing degree days. The adults will begin to appear around 300 growing degree days. Given that the eggs are well protected within the bud scales, horticultural oils are usually not effective in managing this life stage. Once leaf cupping occurs, the nymphs are also somewhat protected from oil sprays and insecticidal soaps. Some products labeled for boxwood psyllids: Azatin, Chlorpyrifos, Horticultural Oils, Insecticidal soaps, Merit, and Sevin. Periodical Cicadas Due In West Kentucky By D. W. Johnson & L. Townsend Extension Entomologists, and R. E. McNiel, Horticulture Brood XXIII of the periodical cicada is due to emerge west of I-65 in Kentucky this year. This is a 13-year brood so the last emergence occurred in Adults will be active from April through June. There are two aspects of periodical cicada damage. The most obvious occurs as females lay their eggs in small branches. A second, delayed effect can occur as the nymphs feed on sap that they remove from the roots during their long life below ground. Egg laying injury occurs when female cicadas slit the bark on pencil-sized twigs and lay their eggs inside the wounds. They prefer grapevines and oak, hickory, apple, peach and pear trees. This results in "flagging," or breaking of peripheral twigs on small trees or shrubs. Young trees may be fatally harmed by severe flagging. More mature trees and shrubs usually survive even dense emergences of cicadas and continue to grow during subsequent years. This can be difficult to believe in the month or so following a large emergence because many deciduous trees will turn brown due to breakage and death of peripheral twigs. Cicada damage can easily destroy the current year's growth so increased pruning is required to get rid of damaged areas. The most serious consequence for nursery plantings will be the injury to usable living branches which provide the basic structure for the plant. These

5 wounds cause a weak point so branches that are gathered together and tied during harvest and shipment are broken very easily. In order to have quality trees to harvest in a production nursery, one may have to remove 1 to 2 years of growth in order to develop usable branches on a finished product. This may mean that the trees near the end of their production cycle may be rendered useless as a marketable crop during the fall after emergence or during the next year. Below ground feeding by large numbers of nymphs can cause long-term damage. Once they have burrowed into the ground and reached the roots, no control method is available. During the first five years, feeding by the nymphs probably will not be noticeable. However for years 6 to 13 of the life cycle, cicada nymphs may be extremely destructive to plants, especially those that bear fruit. In general, cicada damage will not be of any importance on fully-grown shade trees, although the current year's growth may be reduced. Because egg laying is the real danger from these insects, consider emergence as the signal to begin protecting plants. A week or so after emergence, females are ready to lay eggs. Plants can be protected in three ways: covering, spraying and pruning. Small trees can be covered with a protective netting cheesecloth. Be sure to secure the bottom around the trunk. This covering will have to stay on for the next four to six weeks or until egg laying is complete. Insecticides can be used to reduce damage by cicadas but several applications may be needed. Dursban (chlorpyrifos) and Sevin (carbaryl) are labeled specifically for periodical cicada control. Several synthetic pyrethroid insecticides are labeled for landscape trees and shrubs. Often, these insecticides have a repellent effect that causes insects to leave treated surfaces shortly after landing on them. The following examples do not list the periodical cicada but are broad spectrum products that are effective against a wide range of insects - Astro (permethrin), Decathlon 20 WP or Tempo (cyfluthrin), DeltaGard T&O (deltamethrin), and Scimitar (lambda cyhalothrin). Several of these are available only to commercial applicators. Nurseries under a routine spray schedule should be sprayed according to intensity of the outbreak, which can range from a few cicadas in some areas to massive numbers in other areas. During low-level outbreaks application may be needed twice a week. During massive outbreaks, damage will potentially occur even with daily applications. Continued cicada flight to landscapes and nurseries from surrounding woods keeps reinfestation pressure high for several weeks. Control is most effective when the insects are hit directly with spray droplets. Residual control must rely on cicadas sitting on treated surfaces long enough to absorb the insecticide. This can delay or reduce action on the insect. The following are some of the products available to homeowners: Lawn and Garden Insect Killer (cyfluthrin) and Ortho Bug B Gone Spray (esfenvalerate). Spectracide Bug Stop Multipurpose Insect Control Concentrate and Total Pest Control Outdoor Formula contain (permethrin). Be sure to read the product label closely because many of these products are not labeled for fruiting plants and trees that are bearing. A third alternative is to prune out egg-laying wounds before eggs hatch, especially in fruit orchards where juveniles feeding on roots may decrease fruit production. Although this is a time-consuming process, it may be a viable alternative considering the production life and long-term value of fruit trees. Eastern Tent Caterpillar Egg Hatch In Central Tennessee & West Kentucky by Lee Townsend, Extension Entomologist Frank Hale and Alan Windham of the Tennessee Cooperative Extension Service reported the start of ETC egg hatch on black cherry trees in south Nashville on March 14. Leaves are just beginning to expand on the trees there. Doug Johnson reported fresh hatch of one of the masses that he is watching in Princeton. It is premature to consider an insecticide application at this time. The rate of ETC egg hatch is strongly affected by temperature. At a constant temperature of 77 F, 90% of the eggs should hatch in about 8 days. At 50 F, it takes about 30 days for 90% of the eggs to hatch. An unseasonably warm spell over the next 10 days or so with temperatures in the low 70's will favor egg hatch and result in most of the caterpillars out and feeding in a relatively uniform group. However, a period of days with highs in the low 50's or below should prolong egg hatch over a much longer period. This should be taken into account when planning insecticide applications. Allow tents to develop rather than treating as soon as the first larvae are seen. Both egg hatch and caterpillar growth will be slower during cool temperatures. ETC larvae tend to leave their tents and feed at three relatively predictable times during the day - about 6 am, 3 pm, and 8 pm. Nearly 80% of their feeding activity occurs during the darkness near dawn and dusk. The morning and evening activity periods tend to be about twice as long as the one in the afternoon. These feeding times are very synchronized when the caterpillars are small and begin to be come less organized as they get older. This behavior provides 2 advantages to them: 1) they are active when the risk of being eaten by birds is reduced and 2) they can digest their food and empty their gut in their tents during the warmer part of the day and leave it with an empty stomach when it is time to feed again. This behavior can be used to advantage in timing an insecticide application immediately before ETC begin a major feeding spurt. An afternoon application, weather permitting, should be an effective strategy for 2 reasons. 1) ETC larvae spend a lot of time feeding at dusk and around dawn, so the insecticide residue will be "fresh".

6 2) Bt insecticides (DiPel, etc.) are broken down rapidly by sunlight. This application time reduces the exposure of the residue to UV light prior to feeding periods. Degree-Day Targets for Ornamental Plant Pests In 1988, Warren Johnson of Cornell University produced one of the most comprehensive lists of insects and mites that attack trees and shrubs and associated Degree-day (DD) activity periods. These DD periods were not developed using rigorous observations and model development. They were developed by taking yearly notes of insect and mite activities. These notes were then compared to DD charts for those same years and a range of DDs (base 50 F) were recorded. The original list of insects and mites has been reduced to those that are of importance to Tennessee operations. The box below will be a regular feature in the newsletter. This box will contain several cities across the state. Use the city closest to you and use those degree-day totals to determine pest activity for your area. As you can see, there can be quite a variation across the state. Also, please note the differences between the years. This is a result of cooler temperatures and as a result, pests will be occurring later. This shows why spraying on a calendar basis does not always offer the best control. Degree Day Totals through March 26, 2002 Bardstown Louisville - 90 Bowling Green Mayfield Henderson Paducah Huntington, WV Princeton Lexington 90 Quicksand London Somerset 138 Degree Day Totals through March 26, 2001 Bardstown - 42 Louisville - 36 Bowling Green - 64 Mayfield - 38 Henderson - 48 Paducah - 47 Huntington, WV - 48 Princeton - 60 Lexington 42 Quicksand - 38 London - 46 Somerset 51 Degree Day Totals through March 27, 2000 Bardstown Louisville Bowling Green Mayfield Henderson Paducah Huntington, WV Princeton Lexington 162 Quicksand 180 London 174 Somerset 220 The use of brand names and any mention of commercial products or services in this publication does not imply endorsement by the Office of State Entomologist nor discrimination against similar products or services not mentioned. Educational programs of the Office of State Entomologist serve all people regardless of race, color, age, sex, religion. disability or national origin. University of Kentucky, U.S. Department of Agriculture and Kentucky Cooperating. Degree-Day Accumulation Chart Date Max Temp Min Temp Max T + Min T 2 DD501 (Ave T)-50 Cumulative DD50 Remember, a negative number should be changed to a 0 for the day.