PERIODICAL CICADA EGG HATCH underway; GREEN CLOVERWORMS and GRASSHOPPERS in soybeans; FALL ARMYWORM on late corn; HORNWORMS on tobacco; time for preventive sprays for NUT WEEVILS; FOREIGN GRAIN BEETLES being a nuisance in homes; WHITE GRUB INJURY to turf; BLISTER BEETLES feeding on potatoes and tomatoes; SPIDER MITES on landscape plants.
As we approach the final weeks of our traditional blue mold season, the threat from this disease remains low in KY. No new cases of blue mold have been reported in the U.S. since mid-July, and inoculum from existing sites around KY (FL, GA, VA, and PA) has not moved into the Commonwealth. Quite a bit of tobacco has been topped, and more is approaching this stage of growth. In general, the susceptibility of tobacco to blue mold decreases dramatically after topping. This diminishes the chances of a widespread outbreak even further if inoculum of the blue mold pathogen makes its way into the state. The weather for the week of August 4 will continue to be hot, with minimal chances of showers - conditions that are less than ideal for blue mold. Still, we should be on the lookout and be prepared to act if the disease is found and if conditions are favorable for development and spread of blue mold.
We continue to receive a fair number of cases of black shank being reported. Tobacco streak virus has been confirmed on samples from a number of counties. This virus is vectored by thrips, as is the tomato spotted wilt virus, and populations of this insect have been high this season. Target spot is still at low levels around KY, although recent rains have created conditions that favor this disease. Quadris can be applied up to the day of harvest for management of target spot, as well as blue mold and frogeye leaf spot; however, treatments made just before or after topping will have the best effect. An application of Quadris could be warranted in areas where disease has been severe in the past, or where significant spotting has been found in the lower canopy prior to topping.
For the latest blue mold status and other tobacco disease information, check the KY Blue Mold Warning System online.
For more information about tobacco pests, visit "Insect Management Recommendations".
Numbers of soybean aphid in Kentucky remain very low. An additional finding was reported from Todd Co. this past week, but it was a single aphid. The only reports in Kentucky have indicted very small populations.
However, soybean aphid populations are beginning to grow in the upper mid-west. Several states including Iowa, Minnesota and South Dakota have populations that exceed the economic threshold. Reports from far northern Illinois indicate populations are rapidly increasing.
Soybean aphid movement is being observed through the Aphid Suction Trap network. Many traps in the north central states are capturing flying aphids. However, the traps in Kentucky (Princeton & Lexington) and in Missouri (Portageville & Colombia) have NOT captured any. The closest capture appears to be in northern Illinois.
For the present, Kentucky is still far from chances of a significant infestation. Additionally, the predicted very hot and humid weather of this week is likely to suppress aphid reproduction of the few that are here. Nevertheless, there are many soybean fields with plants in the very early vegetative stages. These are the areas that could be subject to soybean aphid outbreak later in our season, particularly in September when the weather tends to cool down. Producers, consultants and scouts should continue to watch for this pest.
For more information about soybean pests, visit
"Insect Management Recommendations".
During some years, straw itch mites can make life miserable for people handling hay. The mites are virtually impossible to find because of their size and the fact that they quickly drop off after biting. Diagnosis often is based on symptoms and location of the lesions.
The straw itch mite (about 1/125 inch long) feeds on caterpillars, beetle larvae, and other small arthropods in hay fields or stored grain. Most reported outbreaks affect people who harvest or handle grains or hay. Mites are physically transferred to the skin during handling or may be picked up from infested straw used for mulching or decoration. The mites probably are present in most fields every year with occasional population explosions when conditions are very favorable.
Proteins, injected as the mites pierce the skin with their needle-like mouthparts, can cause moderate to severe skin reactions and itching that can last for 10 to 14 days. The itching typically is noticed from 2 to 12 hours after exposure, by then the mites often gone. Skin reactions can include dozens to hundreds of small, solid, raised areas that may have white tops (pustules). They occur most often on the neck, back, abdomen, and around the waist. In contrast, chigger bites are commonly found on the legs. The lesions disappear in a few days, with or without therapy. Severe reactions in some individuals can include fever and vomiting and may require hospitalization. Oral antihistamines and topical anti-itch creams have been reported to be useful in alleviating the discomfort caused by the bites. In most cases the bites clear in a about a week. Persons with prolonged discomfort should see a physician.
People working with hay / straw) should wash frequently and thoroughly with soap and water. Remove clothing and launder each day, the mites may be able to live for several days. There is no evidence that the bites transmit disease, nor that there is a person to person transmission of the mite.
Insects are one of the possible causes of areas of brown turf in late summer. Grass species and damage signs can be keys to identifying the cause.
White grub infestations, caused primarily by masked chafers and Japanese beetles, appears around mid-August, especially in Kentucky bluegrass. Damage by the grubs allows the rootless turf to be rolled up like a piece of carpet. The grass blades are undamaged and C-shaped white grubs usually can be found right at the soil surface. In moderate infestations, extra watering may keep the grass alive and allow it to survive until grub feeding ceases and roots can re-grow. Application of a "24-hour grub killer" product containing trichlorfon may be needed in heavy infestations. The area should be irrigated after treatment to move the insecticide into the root zone.
Several species of sod webworms occasionally can damage turf. These caterpillars chew off grass blades just above the plant crown, in effect "scalping" areas of the turf but leaving the root system intact. On close inspection, dark green fecal pellets left by the caterpillars can be found all over the surface. Initial damage often appears as baseball-sized brown patches that increase in size as the caterpillars feed. Sod webworm damage is most noticeable during dry periods and show up first on steep slopes and banks. Extra irrigation may help grass to survive. Several turf insecticides are labeled for sod webworm control.
Infestations of the hunting billbug have been reported from zoysia and Bermuda grass on golf courses this summer. The legless larvae with yellow-brown heads are foot feeders. The adults, brown to black snout beetles, eat grass leaves and burrow into stems. Signs of infestation resemble fertilizer burn.
Insects are only one potential cause of turf damage. Diseases, environmental conditions, and other factors also are factors to consider.
During the past week, the PDDL received samples of black shank, soreshin, brown spot, target spot, Pythium root rot, and manganese toxicity on tobacco; Pythium damping off, thrips damage, alfalfa mosaic virus, bean pod mottle virus, and potassium deficiency on soybean; potassium and magnesium deficiencies in corn; and potassium deficiency in alfalfa.
On fruits and vegetables, we diagnosed cedar-apple rust and scab on apple; Phytophthora crown and root rot on strawberry; powdery mildew on cherry; southern blight on bean and pepper; bacterial wilt and Alternaria leaf blight on cantaloupe; Verticillium wilt on potato; Rhizoctonia crown and root rot on rhubarb; bacterial leaf spot, tomato spotted wilt virus, early blight and Septoria leaf spot on tomato; common blight on bean; bacterial leaf spot on pepper; and powdery mildew on yellow squash.
On ornamentals and turf, we have seen anthracnose on oak; Gloeosporium leaf spot on birch; powdery mildew on dogwood; Dutch elm disease on elm; cedar-quince rust on juniper; Seiridium canker on Leyland cypress; Pythium root rot on chrysanthemum; Pythium root rot and black root rot on petunia; Pythium root rot and Rhizoctonia root rot on impatiens; brown patch and Pythium root rot on bentgrass; summer patch on bluegrass; and smut on bermudagrass.
July 25-August 1, 2008
||European Corn Borer
||Southwestern Corn Borer
||European Corn Borer
||Southwestern Corn Borer
Graphs of insect trap counts are available on the IPM web site at - http://www.uky.edu/Ag/IPM/ipm.htm. View trap counts for Fulton County, Kentucky at - http://ces.ca.uky.edu/fulton/anr/
NOTE: Trade names are used to simplify the information presented in this newsletter. No endorsement by the Cooperative Extension Service is intended, nor is criticism implied of similar products that are not named.
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