by William Nesmith
A BLUE MOLD WARNING IS ISSUED FOR EASTERN KENTUCKY TOBACCO GROWERS WITH A BLUE MOLD WATCH FOR NORTHERN KENTUCKY.
While most of Kentucky's tobacco has escaped strong blue mold activity since the hot weather of late July, that is not the case in foggy areas of eastern Kentucky. Strong and damaging blue mold activity has been occurring in eastern Kentucky during the past two weeks, especially in communities receiving heavy thunderstorms in late July and early August or where valley fogs prevailed. Most tobacco set in May in the region has escaped damage, and the strong activity is occurring mainly in that set after June 15. As a result of having received more timely moisture than most of the state recently, the tobacco plants in eastern Kentucky have been growing much better than in most other regions and are now highly susceptible to blue mold. Furthermore, during the hotter weather of late July, localized outbreaks continued in hilly eastern Kentucky, and have rapidly increased during the past 10 days. There is now sufficient spore-loads to drive epidemic levels in eastern Kentucky, and also threaten other areas of Kentucky and other states.
If the wet weather develops that is forecasted for August 8 - 13, blue mold could reach epidemic levels rapidly in eastern and northern Kentucky, especially in fields of rapidly growing crops located in foggy areas.
Blue mold activity is very limited in most other areas of Kentucky, however, stopped by the combination of hot weather of mid and late July and tobacco plants that are poor hosts for blue mold due to drought conditions in much of central Kentucky. The disease is established in nearly every tobacco production area of Kentucky and could develop quickly should wet and cool weather return and rapid tobacco growth develop. However, as long as the tobacco plant grows poorly, little damage will occur from blue mold. Blue mold is a disease of rapidly expanding tobacco, so expensive blue mold control inputs should be considered only for crops growing well.
Properly applied fungicide sprays provide the best protection against blue mold, with Acrobat MZ providing excellent protection in my plots. For example, at Quicksand, Ky in our plots at the Robinson Substation, University of Kentucky, weekly applications of Acrobat MZ have provided great control of blue mold - 99% control as compared to untreated checks, which now have 30-60% of the leaf surface spotted. Excellent control is being achieved with either tractor operated or hand-operated spray equipment.
Fungicide sprays are not warranted for most crops outside the watch and warning areas, however, except for communities and situations where isolated outbreaks have persisted, due to irrigation or other water sources. With the cooler weather forecasted for much of the coming week, growers will need to remain watchful and monitor the situation. Greatest threats of damaging blue mold will be with crops having the following characteristics: blue mold is active in the community, crops were set after mid-June and are now rapidly growing but prior to flowering, with one or more of the following additional factors such as a shady site, moisture as irrigated or rainfall, low areas (e.g., river bottoms) or other foggy sites.
by Paul Vincelli
Waste corn can be a source of various insect pests. Thus, disposal of this corn is an important part of a sanitation program for controlling several insect pests of corn, particularly prior to storage. UK Entomologists recommend thoroughly cleaning corn in and around bins, as well as all equipment that will be handling the grain including trucks, wagons, and augers.
Recent Findings
Recently published research from Iowa State University has shown that waste corn can also be a source of Aspergillus flavus, the fungus that can produce aflatoxins in corn. Aflatoxin contamination of corn grain in this part of the country is quite uncommon most years. However, preharvest contamination sometimes does develop when hot, dry conditions prevail during grain fill. Postharvest contamination by aflatoxin is usually associated with unfavorable storage conditions. Aflatoxin contamination of corn is subject to U.S. Food and Drug Administration regulations. See the UK Extension publication, Aflatoxins in Corn, ID-59, for more information.
Regarding waste corn, the Iowa researchers found that deposits of waste corn in and around bins and cribs often were infested extensively with Aspergillus and were sources of airborne spores of the fungus. Aspergillus was found at almost every crib or bin site sampled. Interestingly, the highest levels of Aspergillis contamination in waste corn deposits was under weed canopies, which may have allowed for higher humidities more favorable for sporulation. Also, waste corn was a source of sap beetles contaminated with spores. This also is important since sap beetles may spread spores of Aspergillus to the silks of healthy corn plants, where Aspergillus can begin infection.
Why Is This Important?
Previous research by these investigators strongly suggests that waste corn is not the only source of spores of Aspergillus. Low levels of spores can occur from soilborne sources every year in Iowa, and the same may be true here. However, since waste corn is clearly a source of Aspergillus spores, producers have another good reason to dispose of waste corn besides insect control. It may help reduce the risk of preharvest aflatoxin contamination in an epidemic year for aflatoxin.
One final note: since Aspergillus can infect silks as they turn yellowish-brown, clean up waste corn before silking. This is considerably earlier than the normal practice of cleaning up cribs and bins as one prepares for harvest.
by Doug Johnson
It is the time of year to began looking for soybean podworm. This pest, more commonly known, as the corn earworm (and also the tomato fruit worm) can cause considerable damage to soybeans with few obvious symptoms.
Late planting is one of the several factors which can contribute to the problem. With the spring Kentucky had this season, there is little doubt that many soybean fields had a late plant date. Look first at late planted fields and especially if a canopy has not formed to cover the rows. Second, if the corn in the area is mature and drying up, moths of this pest will move out of the corn and into soybean to lay their eggs. Corn planting dates were also extremely variable and so the relative maturity of fields adjacent to soybeans will vary quite a bit.
The damage from these insect is very distinctive and should be easily identified. Soybean podworm eats a large hole in the side of the pod. The worms are very small -- to 1" in length when full grown. They are usually tan to pale green with several dark stripes down the back. However, color may be quite variable, with some individuals being almost black
It is very important that you get out into the fields to check for this pest. Soybean podworm very seldom feeds on leaf tissue. They tend to stay down on the pods, so if you just take a general look at the field you may not notice them. You must get down and look at the pods. In general, the shake clot method of sampling is preferred. The economic threshold for controlling this pest is two worm per row foot.
by Lee Townsend
Orange-striped oakworms are black caterpillars with eight narrow yellow stripes that run the length of the body. There are a pair of long, curved "horns" behind the head. Small larvae feed in groups and skeletonize the leaves, older larvae eat all of the leaf except the main veins. They usually destroy all of the leaves on a branch before moving to a new feeding site. Infestations usually start in the top of the tree and the larvae move down as they feed and destroy foliage. Sprays of B-t (Bacillus thuringiensis - Dipel, etc.) will control these insects. B-t works as a stomach poison so treated leaves must be eaten. Direct spraying of the caterpillars will not kill them.
by Lee Townsend
Velvet ants, also known as "cowkillers" are large and furry like a bumble bee, but are marked with red and black or orange and black. Actually they are a type of wasp with a very long stinger and a potent venom. The "cowkiller" name refers to the pain of a sting.
Velvet ants can be seen running around in the yard during late summer. They are parasites of bees and wasps that nest in the ground. Velvet ants prefer bare areas in sandy soil where their prey are most likely to be found. There is no effective control measure for them. If they are particularly abundant in an area, it may be helpful in the long run to overseed to get a better grass cover. This would discourage the ground nesting bees and wasps on which velvet ants feed.
by Lee Townsend
Mole crickets are aptly named because their elongate bodies and shovel-like front legs are adapted for burrowing in the soil like moles. They usually occur in light, sandy to loamy soils, often near water. They can uproot plants as they move through the upper soil levels looking for food or disturb the soil so much that it dries out. Mostly they feed on roots and organic matter but they may eat small insects and earthworms, too.
Mole crickets are active and feed on warm nights, especially following a rain or irrigation. They stay in permanent burrows in the soil during the day and during long dry or cold periods. Individual burrows may be up to 14" deep. They seem to prefer moist soil so steps that promote drainage or reducing overwatering can limit their activity. Spiders, skunks, racoons, toads, and birds are among the natural enemies of mole crickets.
Insecticidal control should be attempted during July and August. During this time the larger immature stages and adults are tunneling through the soil in search of food and are most destructive. Diazinon granules, wettable powder, or emulsifiable concentrate, or Oftanol or Dursban granules are registered for mole cricket control. Watering the infested area (or a rain) just before or after application should bring the crickets to the surface and increase control.
by Lee Townsend
Yellow-orange winged ants can cloud the afternoon skies in late summer. Large yellow ants are also known as citronella ants because of the lemony odor given off when they are crushed. These ants nest in the soil under logs, rocks, patios, or concrete slabs but can be abundant in open fields. Usually there is a large pile of fine soil particles at the nest entrance. Large yellow ants feed almost entirely on "honeydew" gathered from root aphids and other sucking insects. Large swarms can be an annoyance to anyone who is outdoors at the peak of ant activity. Some are concerned that these are termites.
Large yellow ants are normally not a household problem unless there are colonies along the foundation and the workers forage in the structure. Direct treatment of the nests, easily recognized by the large dirt piles at the entry, is the key to control in this situation. Ant baits are not too effective against these ants.
by Ric Bessin
One beneficial insect found near lawns that often concerns homeowners is the white grub parasite, Scolia dubia. These solitary wasps are sometimes seen hovering over the turf in late summer in search of green June beetle and/or Japanese beetle grubs on which to lay their eggs. The wasp larvae then kill the grubs as they develop.
Scolia dubia is a sleek and hairy wasp that has dark, steel blue wings and body. The rear half of the abdomen orange with two light yellow spots on the first orange colored segment. These wasp are usually seen flying low over lawns in the afternoon.
While these wasps are able to sting, they are not aggressive and normally will not sting people unless handled or stepped upon. Unfortunately they won't completely control problems causes by white grubs, they provide some natural suppression and should be conserved if possible.
by Ric Bessin
The clover hayworm moth is a common household invader in the late summer and fall moths. There is no doubt that they can become a nuisance, however, they do not feed, cause damage or reproduce within homes. These moths are truly accidental invaders, they are attracted to homes at night either by indoor and outside lights. The peak month for hayworm month submissions is November, although we have received specimens from August through November.
The moth is purple-gray in color, fringed with golden yellow, and have two small golden triangles on the leading edge of the front wing. The brown larva attacks stored clover hay and is not found in homes, but can be common in barns. Although this moth can be a nuisance, they are not damaging, and are very short lived in the house. Avoid leaving lights on for prolonged periods of time near doors and windows. The moths frequently disappear on their own and insecticide treatment is seldom warranted and otherwise ineffective.
by Ric Bessin
Most people know that bees, wasps, hornets and some ants can sting to defend themselves or their nests. Only a few people realize, usually from first hand experience, that handling or brushing against some caterpillars can produce some painful results, also. Recognizing the few stinging caterpillar species may prevent unpleasant encounters. Common stinging caterpillars in the early fall include the saddleback caterpillar and the stinging rose caterpillar.
Saddleback caterpillar is brown in front and rear, green in the middle with a purple spot in the center of the green saddle. There are prominent horns on the front and rear. Stings by this insect can cause severe irritation. Saddlebacks are typically found on deciduous trees such as basswood, chestnut, cherry, oak, and plum, but occasionally they can be found on corn.
The stinging rose caterpillar is a yellow to red spiny caterpillar with black and blue stripes down the middle of its back and less distinct red, blue and black stripes along the side of the body. There are prominent spiny yellow horns on the front, rear and center of the body. They can be found feeding on bushes and low tree branches of redbud, oak, hickory, bayberry, wild cherry and sycamore.
Most encounters with stinging caterpillars result from accidently brushing against leaves on which they are feeding. The chances of running into these insects are relatively low, but occasionally one species may be very abundant. Also the more time spent in wooded areas, the greater the opportunity for contact. Most of these caterpillars are distinctly marked or brightly colored. This allows you to see and avoid them. If you find one on yourself, don't brush it off or slap it with a bare hand. Use a stick or other object to remove it carefully. Hollow spines may break off in clothing or gloves.
For more information on stinging caterpillar, see ENTFACT-003, Stinging Caterpillars.
by Julie Beale and Paul Bachi
Fusarium crown/ root rot on alfalfa and on soybean was diagnosed last week. On tobacco, we are seeing black shank and soreshin in complex, blue mold, Fusarium wilt, target spot, frogeye leaf spot, false broomrape, calcium deficiency, potassium deficiency and the complex of symptoms associated with acid soils.
On turf , summer patch and necrotic ring spot were diagnosed on Kentucky blue grass and tall fescue, and also brown patch on fescue. On chrysanthemum, we have seen bacterial leaf spot and Rhizoctonia root and crown rot.
| Princeton | |
| European Corn Borer | 0 |
| Corn Earworm | 2 |
| Fall Armyworm | 3 |
| Tobacco Budworm | 0 |
| Allen Co. | |
| European Corn Borer | 0 |
Lee Townsend
Extension Entomologist