WHAT S HAPPENING? The University of Tennessee/Agricultural Extension Service Entomology & Plant Pathology - EPP #60

Transcription

1 WHAT S HAPPENING? The University of Tennessee/Agricultural Extension Service Entomology & Plant Pathology - EPP #60 Volume No. 8 - June 27, 2003 QUITE A YEAR FOR RUST by Alan Windham A few years ago, Bailey White wrote a novel, Quite a Year for Plums, about a plant pathologist working in South Georgia. If she had written it this year, Quite a Year for Rust would have been appropriate. I have gotten several calls about rust (Gymnosporangium clavipes) on hawthorn. This cedar rust is a close relative to the rust that causes cedar/apple rust. It attacks the leaves, stems and fruit of certain hawthorn cultivars. The infected fruit almost has an ornamental look to it. Washington hawthorn may be damaged when the rust infects young stems, killing all growth past the gall; leaves and fruit are also infected. Winter King hawthorn is usually not damaged severely, but this year, almost all of the fruit on some trees is infected. Don t expect much of a show from red fruit this winter on hawthorn. Much of the fruit will be mummified or drop to the ground. Also, I have seen this rust on serviceberry and crabapple this week, infecting the fruit. To prevent this damage, spray hawthorn mid-to-late spring when spores are blown from cankers on eastern red cedar. ORNAMENTAL DISEASES by Alan Windham Foliar phytophthora blight on vinca is showing up in landscape beds. This disease can wipeout a planting of vinca, especially if it is irrigated. It s a top down disease, killing the foliage from the tip of the plant downward. Reducing irrigation, mulching, rogueing and spraying with mancozeb may slow this disease. Entomosporium leaf spot is really damaging photinia this year. I ve seen many photinia screens in Middle Tennessee, totally defoliated by this disease. This is a good reminder, why photinia is a poor choice for most Tennessee gardens. Control is possible, but impractical for most. Pruning back shrubs, removing fallen leaves and spraying frequently with Daconil are a commitment that most gardeners won t make; and honestly, shouldn t have to, to have a decent hedge or screen. (1 of 7)12/5/2012 6:50:39 AM

2 DEAD FLIES STUCK ON LEAVES AND OTHER CURIOSITIES by Frank A. Hale We have been seeing scores of dead flies stuck to the underside of leaves the past few weeks. These flies were killed by a fungus, probably Empusa muscae. The fungal hyphae develop inside the fly and cause it to swell. The light tan color hyphae can be seen arising from the folds between the darker abdominal segments giving the fly a banded bee-like appearance. Closer examination will reveal that these are indeed dead flies with only one pair of wings and not two pair as with a bee. The process continues until the whole abdomen and all around the edge of the thorax turns a tan color from the sporulation. The hyphae attaches the fly to the leaf where it will stay until natural weathering and further decomposition causes it to no longer persist. I expect that the prolonged wet weather of past weeks has been conducive to spore germination and fungal growth. I am not sure why the flies are found congregated on the underside of the leaf other than that is their natural resting place. Flatid planthoppers will leave a white waxy residue on the stems of shrubs and other landscape plants. The nymphs are covered with waxy filaments, some of which remains on the twig. Their feeding does not seem to harm the plants but the residue bothers people. It can be wiped off with soapy water while control for the pest is usually unnecessary. We have also observed the Asian woolly hackberry aphid on the leaves of hackberry and sugarberry. These tiny aphids are covered with fluffy, white wax filaments. Many of the adults are winged and these white insects seem to float about. Look for the populations to build over the next three months. The copious amounts of honeydew will drip on leaves and anything else found beneath the trees. Sooty mold will turn the trees and any stationary objects beneath them black. The best approach for a large tree would be to drench the root zone soil with imidacloprid (Merit) back in the spring. It still may not be too late for this approach. Tree injection products containing imidacloprid can be used now to give season-long control of this nuisance pest. On smaller trees, horticultural oil or Merit sprays can be applied to the foliage. A repeat application may be needed later in the summer, if populations start to build again. Japanese beetle adults are moving into new areas across the state. Sevin is still a good choice for periodically spraying favorite host plants of this pest. We have seen success with drenching the soil with Merit in the spring prior to their emergence. This systemic insecticide prevents much of the feeding damage and if soil applied should more than last the season. Homeowners can purchase imidacloprid for use as a drench as Bayer Advanced Garden Tree & Shrub Insect Control. (2 of 7)12/5/2012 6:50:39 AM

3 PUTTING WEST NILE VIRUS AND OTHER MOSQUITO- TRANSMITTED DISEASES IN PERSPECTIVE by Karen M. Vail An article that will help clients put the risks of mosquito-transmitted diseases into perspective is presented below. But first, I want to remind you of ways to protect yourself from mosquito bites. Remember, when outdoors, it is wise to protect yourself with insect repellent. Guidelines for using insect repellent and other ways to prevent mosquito bites, such as reducing nearby standing water, can be found at the CDC s web sites ( insect_repellent.htm and We are developing a web site pertaining to mosquitoes, diseases, and mosquito control and prevention, but don t expect it to be launched for a few months. Mosquito Diseases in Perspective, by Mike Potter of the University of Kentucky Cooperative Extension Service, follows. Apart from the annoyance, the blood-feeding habits of adult mosquitoes can occasionally result in life-threatening diseases. Malaria and yellow fever used to be common in the United States, but they have been successfully eliminated through widespread public health efforts. Currently, viral encephalitides are the most common mosquito-borne illnesses transmitted to people. "Encephalitis" simply means an inflammation of the brain and can be caused by a variety of pathogens in addition to those transmitted by mosquitoes. Mosquito-borne strains of viral encephalitis include Eastern Equine, Western Equine, St. Louis, LaCrosse and (most notably), West Nile. Birds and small mammals are important natural hosts for these viruses, which are transmitted to humans and horses through the bite of an infected mosquito. Symptoms of viral encephalitis in humans range from mild to severe and may include high fever, vomiting, drowsiness, and convulsions. Mortality rates vary with the strain of virus involved, e.g., up to a 50 percent risk of mortality with Eastern Equine encephalitis compared to less than a 1 percent mortality rate for West Nile. West Nile Virus West Nile virus (WNV) was first isolated in 1937 in the West Nile province of Uganda, and is common in Africa, eastern Europe, western Asia, and the Middle East. The disease first became apparent in the United States in the summer of 1999, when an outbreak occurred in New York City. In subsequent years it quickly spread from coast to coast, infecting birds, horses and humans. By the end of 2002, West Nile virus activity had been documented in 90% of Kentucky counties in either birds, horses, humans or samples of mosquitoes. (3 of 7)12/5/2012 6:50:39 AM

4 Mosquitoes become infected after biting infected wild birds, which are the primary host for the virus. The virus multiplies within the mosquito's body, and is transmitted to animals while taking a blood meal. Other than birds, WNV is most likely to cause illness in horses and humans. Dogs and cats appear to have a much lower risk of infection. Unlike such illnesses as influenza, WNV cannot be transmitted from person-to-person by sneezing, coughing, touching or kissing. Most people infected with WNV experience few if any symptoms. A small percentage develop fever, headache, body aches, swollen lymph glands or skin rash. Less than one percent of infected people experience more severe symptoms, which may include headache, high fever, neck stiffness, disorientation, convulsions, paralysis, and sometimes death. Elderly persons are most at risk of suffering severe symptoms. In 2002, there were about 4200 confirmed cases of WNV in the U.S. and 277 deaths. Seventyfive cases and five confirmed deaths occurred here in Kentucky. While the virus is clearly a public health concern, about 41,000 people die each year from motor vehicle accidents, 64,000 from pneumonia/influenza, and 430,000 from smoking-related illnesses. Although some people are indeed bitten by disease-carrying mosquitoes, the risk of serious infection is extremely low compared to other risks we encounter each day. Serious health effects can be further reduced by promptly seeing your physician if symptoms arise. PLANT & PEST DIAGNOSTIC CLINIC HIGHLIGHTS by Tom Stebbins and David Cook The following samples were submitted to the clinic June 12 through June 26, 2003 TOBACCO: Black shank and black root rot on burley tobacco; nutrient or ph related problems. ORNAMENTAL AND TURF: Fireblight on ornamental pear; anthracnose on oak; botryosphaeria canker on dogwood; bacterial leaf spot on oak leaf hydrangea; bacterial leaf spot on English ivy; fungal canker on Japanese maple; rhizoctonia stem rot on petunia; phomopsis blight on aucuba; entomosporium leaf spot on red tip photinia; black spot on rose; Dutch elm disease on winged elm; black canker on willow; powdery mildew on euonymus; powdery mildew on dogwood; fungal leaf spot on hemlock; botryosphaeria canker on rhododendron; volutella canker on boxwood; black spot of rose; cylindrosporium leaf spot on weeping mulberry; cedar hawthorne rust on hawthorne; phytophthora blight on petunia and artillery fungi spores on a vinyl sided home.. (4 of 7)12/5/2012 6:50:39 AM

5 Turf: Anthracnose, dollar spot and take-all patch on bentgrass; bermudagrass decline on bermudagrass; drechslera leaf spot and brown patch on fescue. FRUITS AND VEGETABLES: Entomosporium leaf spot on pear; anthracnose on strawberry; black rot and anthracnose on grapes; septoria leaf spot and buckeye rot on tomato. INSECTS: Obscure scale on willow oak; oystershell scale on stewartia; armored scale on leyland cypress; euonymus scale on euonymus; obscure scale on willow oak; tuliptree scale on tulip poplar; fourlined plant bug on forsythia; whiteflies on greenhouse tomatoes; pouch galls on black cherry caused by eriophyid mites; Japanese beetles on rose; azalea lacebug injury on azalea In and around the home: Clothes moths; carpet beetles; drugstore beetles; odorous house ants; Native American army ants; Formica ants; field ants; Allegheny mound ants; brown recluse spiders; black widow spider; jumping spider; lyctid powderpost beetle; maize weevils; drywood termite fecal pellets; springtails; trapdoor spider; Maple Dryobius longhorn beetle; SUDDEN OAK DEATH FOUND IN CANADA by Beth Long Source: Canadian Food Inspection Agency News Release The Canadian Food Inspection Agency (CFIA) is investigating a report of Sudden Oak Death (SOD), Phytophthora ramorum, in a British Columbia wholesale nursery. A single rhododendron plant was discovered infected with SOD during a traceback investigation. The traceback was initiated after the United States declared a positive find of SOD in a nursery shipment to Canada. Sudden Oak Death could affect a number of common plant species, including rhododendrons, viburnum, and camellia - in addition, some species of oak, maple, and Douglas fir trees are known to be at risk. The CFIA is responding to this new SOD report by following up on additional tracebacks and taking strict regulatory and sanitary control measures to prevent the spread of this disease. The nursery where the case of Sudden Oak Death was found is a wholesale nursery, and does not sell plants to the general public. Strict regulatory control measures are being taken to destroy all identified plant materials and put sanitation measures are in place to prevent the spread of the disease. For the full news release from the CFIA, see the following: corpaffr/newcom/2003/ e.shtml (5 of 7)12/5/2012 6:50:39 AM

6 EPA REGISTERS MICROBIAL FUNGICIDE ASPERGILLUS FLAVUS AF36 FOR USE ON COTTON by Beth Long The U.S. Environmental Protection Agency has conditionally registered Aspergillus flavus AF36 for use on cotton to reduce aflatoxin contamination. Aspergillus flavus is a common fungus that is most often found where certain crops such as cottonseed, corn and peanuts are grown under stressful conditions such as drought. Aflatoxin is a naturally occurring toxic metabolite from the growth of some strains of Aspergillus flavus. Aflatoxin contamination of cottonseed causes significant economic losses annually because cottonseed is a preferred feed for dairy cows. Aflatoxin in contaminated seed can be transferred to milk, and milk that exceeds the FDA-acceptable limits of aflatoxin is typically discarded, and the dairy quarantined. There are no chemical alternatives registered specifically for control of aflatoxin producing strains of A. flavus. Since 1996, this microbial fungicide has been used successfully in research trials in Arizona and Texas under an Experimental Use Permit (EUP). Concurrently with the conditional registration, a permanent tolerance exemption for residues of Aspergillus flavus AF36 on cotton and its byproducts will be established based on evaluation of data submissions and the temporary exemption established under the EUP. Source: EPA Pesticide Program Update 06/25/03 (6 of 7)12/5/2012 6:50:39 AM

7 Precautionary Statement To protect people and the environment, pesticides should be used safely. This is everyone s responsibility, especially the user. Read and follow label directions carefully before you mix, apply, store or dispose of a pesticide. According to laws regulating pesticides, they must be used only as directed by the label. Persons who do not obey the law will be subject to penalties. Disclaimer Statement Pesticides recommended in this publication were registered for the prescribed uses when printed. Pesticide regulations are continuously reviewed. Should registration or a recommended pesticide be canceled, it would no longer be recommended by The University of Tennessee. Use of trade or brand names in this publication is for clarity and information; it does not imply approval of the product to the exclusion of others that may be of similar, suitable composition, nor does it guarantee or warrant the standard of the product. The Agricultural Extension Service offers its programs to all eligible persons regardless of race, color, age, national origin, sex, veteran status, religion or disability and is an Equal Opportunity Employer. COOPERATIVE EXTENSION WORK IN AGRICULTURE AND HOME ECONOMICS The University of Tennessee Institute of Agriculture, U.S. Department of Agriculture, and county governments cooperating in furtherance of Acts of May 8 and June 30, Agricultural Extension Service Charles L. Norman, Dean (7 of 7)12/5/2012 6:50:39 AM