Blue mold remains active in communities where valley fogs prevail, especially in eastern Kentucky. Activity is very limited in most areas, however, stopped by the hot weather of mid and late July. Sunny days have prevented most medium and long range spread (interstate and community to community), but conditions have been favorable for short range spread (from nearby beds and within fields), keeping the disease active on ground suckers and cooler areas of the field. As a result, no additional counties were added to the list of active blue mold last week, but it remains active to some level in counties reporting activity prior to the very hot weather.
Fungicide sprays are not warranted for most crops, but there are communities and situations where properly applied fungicides could be economically beneficial. Younger crops, set after mid-June, will need to be monitored closely, especially in eastern and northern Kentucky where cooler temperatures exist. With the cooler weather forecasted for much of the coming week, communities near large lakes should also remain watchful and monitor the situation. Greatest threats of damaging blue mold will be with crops having the following characteristics: blue mold active in the community, crops set after mid-June and rapidly growing, with one or more of additional factors such as a shady site, irrigated, low areas (e.g., river bottoms) or other foggy sites.
Late last week, an abundance of new blue mold lesions were evident in foggy valleys of eastern Kentucky and irrigated fields of the Bluegrass. However, as predicted, sporulation was low or did not develop from most of these lesions. But in the coolest areas of the field there were also small pockets of moderate to strong sporulation.
Many tobacco plants in Kentucky are "plastered" with small black winged insects. Some are the winged forms of the tobacco aphid but a large proportion of them are not. The "are nots" include winged ant swarmers and winged forms of other aphid species, such as the potato aphid. These do not colonize tobacco. The best test for determining whether or not the winged aphids in a field are tobacco aphids is to look for colonies of wingless aphids. The ability to produce surviving offspring on tobacco is the key to recognizing the pest.
Don't spray tobacco just because "gnats" are present on the leaves. In many cases, they are not insects that present a threat. Use the presence of live wingless aphids as your guideline. Treat when 20% of the plants in the field have colonies of live wingless aphids in the leaves at the top of the plant. Either Orthene or Golden Leaf Tobacco Spray are effective against tobacco aphids if applied according to the treatment guideline. Once tobacco is topped, the threat of yield losses to tobacco aphids ends.
The first generation of tobacco hornworms is about over but the second, and by far largest brood, is just getting underway. Hornworms pose a serious problem for the small plants present in many fields. These caterpillars are capable of eating most of the foliage on plants stunted by poor growing conditions or in fields that were set late. Watch tobacco closely as long as it remains in the field. Damaging numbers of hornworms can occur on topped and untopped tobacco. Weekly field checks will allow detection of infestations and timely treatment. Be sure to check fields about a week prior to cutting. Hornworms will survive on wilting tobacco and can continue to feed in the curing barn. B-t products, such as Dipel, can be applied just before harvest with no danger to field hands or chances for unacceptable residues.
It is good to be back in Kentucky after a sabbatical in France. I was pleased to have been able to concentrate on one disease, apple scab, and hopefully my research and experience will benefit our Extension programs and the growers of fruits and landscape plants in Kentucky.
As we were descending to the Northern Kentucky/Cincinnati Regional Airport at the end of our long voyage from Paris last week, I noticed a distinct layer of thick brown haze layered in the atmosphere several thousand feet up. Although visible only as a faint haze from the ground or from above it, it looked pretty dirty. The same brownish haze could be viewed on the subsequent flight to Lexington. Perhaps we need to be on the lookout for symptoms of oxidant air pollution damage to some of our more susceptible plants this week. Summer air stagnation events in Kentucky are often followed by chlorotic flecking or bronzing symptoms on plants such as grapes, tobacco, cucurbits, and soybeans.
In Lexington, I noticed that dogwood powdery mildew seems to be worse than it was last year, which was worse than the year before. I certainly hope that this yearly trend does not continue.
A sincere thank you is extended to colleagues in the plant pathology extension group for their help in maintaining the Kentucky plant pathology program in my absence.
Alfalfa seeded during late summer is susceptible to a potentially destructive disease--Sclerotinia crown and stem rot. Fall-seeded stands often have not had sufficient time to develop some resistance by the time spores of this fungus are produced in late October. In contrast, spring- seeded stands usually have developed sufficient resistance to withstand attack should Sclerotinia trifoliorum be present in the field. The level of stand loss in fall- seeded fields varies from none to 99%.
One of the few management suggestions we can offer for this disease is to sow as early as possible in the late-summer seeding window. Producers in Kentucky commonly sow alfalfa anytime from about mid-August to the third week in September. Field research has pretty well documented the fact that, the later one sows during this window, the greater the risk of significant stand loss from Sclerotinia crown and stem rot. From the standpoint of this disease, sowing alfalfa today is not too soon, since even alfalfa sown in early August can suffer substantial stand loss under severe disease pressure. Early sowing just improves your chances against this disease.
There is another side to this coin of early sowing, of course. The earlier one sows, the greater is the risk of seedling loss if a rainy period allows seed germination but then is followed by a hot, dry spell that kills the seedlings. One thing is for certain, however: waiting to sow until the second or third week of September will set the stand up for dramatic stand loss should the disease be active later this year.
There are no alfalfa varieties with meaningful levels of resistance to Sclerotinia crown and stem rot, at least under the conditions we experience in this state. See the Kentucky Pest News article from 28 May 97 for more information on the question of resistance of alfalfa varieties to the disease.
Factors That Suggest Increased Risk of the Disease for Any Given Field Include the Following:
Several species of blister beetles occur in Kentucky and adults are active now. Some were reported in alfalfa hay from a field cut last week in Meade county. Blister beetles contain cantharadin, a protective chemical that can be deadly to horses and can make cattle sick cattle.
Blister beetles feed on flowers so fields cut while alfalfa or weeds are blooming can contain enough blister beetles to raise a concern. These insects generally occur in groups so there can be concentrations of them in a field that would be difficult to detect. Avoid letting fields "bloom"; this will keep them from being attractive to beetles. If flowers are present, do not crimp or crush the hay at harvest; allow it to fall and wilt. The blister beetles will leave the field and the hay can be gotten up with minimum risk of contamination.
The potential for blister beetles in Kentucky hay is very low but the consequences are drastic. Follow good hay management and harvest practices to make the risk of infestation inconsequential. It is not possible to adequately sample hay to assure that the beetles are not present so prevention is the key. See ENTFACT 102 for more information.
Western and northern corn rootworm beetles are now active on corn. While they can cause some damage to the plant and possibly interfere with pollination if their numbers are excessive, even moderate numbers may indicate a potential problem next year if corn is grown in the same field. Counts of western and northern rootworm beetles made during the next few weeks can be used to make soil insecticide recommendations for next year.
The larval stages of these insects are the most destructive. Adults emerging this summer started as eggs laid in last summer's corn and hatched earlier this spring. The western corn rootworm adult is yellow with three black stripes on the wing covers. The northern corn rootworm is similar but without the black stripes. These beetles are silk feeders and may cause a problem during maximum pollen shed. They also feed on leaves by removing the upper surface of the leaf. But the leaf feeding does not normally result in yield loss.
If you see beetles frequently as you walk through the field, select 20 plants from several random locations in the center of the field. Make counts on every third or forth plant until 20 plants are examined. Rootworm beetles fly readily when disturbed so approach plants carefully. Record the number of beetles on the ear tip, tassel, leaf surfaces and behind the leaf axil.
Treatment may be necessary if silks are clipped back to less than 1/2 inch or before 50% of the plants are pollinated and five or more beetles are present per plant. If the counts approach or reach an average of 20 beetles per 20 plants (1 per plant), use a rootworm insecticide if the same field is to be planted in corn next year.
Squash vine borer is active now in central Kentucky. This a key pest of winter squash, gourds and pumpkins. Unfortunately, it is usually noticed only after it has done its damage. Symptoms appear in mid-summer when a long runner or an entire plant wilts suddenly. Infested vines usually die beyond the point of attack. Sawdust-like frass near the base of the plant is the best evidence of squash vine borer activity. If the stem is split open, one to several borers are usually present.
The adult squash vine borer is a stout dark gray moth with 'hairy' red hind legs, opaque front wings, and clear hind wings with dark veins. Unlike most moths, they fly about the plants during the daytime, appearing more like a paper wasp than a moth. Small brown eggs, laid individually on leaf stalks and vines, hatch in seven to 10 days. Newly hatched larva immediately borer into the stem. There are 1 to 2 generations per year.
Squash vine borer management must begin before they enter the stem. Once inside the vine, insecticidal control is ineffective. Poor timing of sprays is the usual cause of inadequate control. Monitor plants weekly from mid-June through August for initial signs of the borer's frass at entrance holes in the stems. Very early signs of larval feeding indicate that other eggs will be hatching soon. Use two insecticide applications 7 days apart to control newly hatching larvae and continue to monitor for additional activity. Sprays need to penetrate the canopy to cover the vines to be effective.
Home gardeners may have some success with de-worming the vines. At the first signs of the sawdust-like frass, vines are slit lengthwise near where the damage is found and the borers removed. The stems should be immediately covered with earth. Sanitation is also important. After harvest is complete, vines should be removed from the garden and composted to prevent the remaining borers from completing larval development. Burying a few nodes along each vine will encourage rooting at these nodes. This will lessen the impact if squash vine borers girdle the base of the vine.
While many producers can readily recognize the damage caused by the brown and green stink bugs in various field, fruit and vegetable crops, not all stink bugs are pests. In fact, the twospotted stink bug, Perillus bioculatus, is beneficial to eggplant and potato producers. This stink bug does not feed on plants, instead it attacks other insects. In particular, it attacks Colorado potato beetle larvae.
The twospotted stink bug is black with two orange lines on the base of each wing. The scuttelum (between the bases of the wings) has a broad orange margin. This 3/4 inch stink bug gets its name from the color of its pronotum (just behind the head) which is orange with two black spots.
The twospotted stink bug by itself cannot eliminate moderate to heavy infestations of the Colorado potato beetle. But they can enhance control when used in combination with other low impact tactics, such as Bacillus thuringiensis var san diego sprays, hand picking, trenching around plots, or transgenic potato lines. Above all, producers and home gardeners need to recognize this natural enemy of our most serious potato pest and not use insecticides to control it! The use of economic thresholds (an average of one beetle or larva per plant on potato; two or more beetles or larvae per plant on eggplant) and careful selection of insecticides (for example, Bt sprays or an Admire application at planting) will help to maximize the benefit of this stink bug in potato and eggplant production.
Experience has shown us that simply relying on insecticides to control Colorado potato beetle leads very rapidly to the development of resistant Colorado potato beetle populations. Recognizing and preserving natural enemies will assist in delaying the development of resistance. The best time to prevent resistance to insecticides is BEFORE it first occurs.
"I keep seeing tiny, brown beetles crawling along the windows, walls, and floors of my new house. I spray the ones I see, but they keep coming back. What kind of bugs are these and how do I get rid of them?" These are the questions typically asked by clients who have foreign grain beetles, especially when the calls occur in late summer (August-September).
Foreign grain beetles are very small (about 1/16-inch long), reddish brown, and are often mistaken for flour beetles or other stored product insects. The key characteristic to look for in identifying this beetle is the presence of a slight projection or knob on each front corner of the the segment directly behind the head. A microscope or good quality hand lens is necessary to see this character.
Foreign grain beetles are frequently problems in new houses (less than 5 years old). These beetles are one of a group of beetles called "fungus beetles" that feed on the molds and fungi that grow on poorly seasoned lumber or wet plaster and wall board. If they are found infesting flour, grain, or other stored products, the products are generally moldy or in poor condition.
When new homes are built, damp wood is often covered with molds or mildew which attracts the beetles. The beetles are also attracted to accumulations of sawdust trapped behind walls during construction. Eggs are laid on this food material and the larvae develop on the surface fungi. The adults usually become a problem in late summer when they move out of wall voids and are attracted to windows and lights. Foreign grain beetles can also be associated with plumbing leaks, condensation problems, or poor ventilation.
There is no fast or easy way to get rid of foreign grain beetles. Control is difficult because the breeding source of the beetles (sawdust, etc) is sealed up within the walls. The ultimate solution is time (and patience). Most new homes dry out naturally within the first 1-4 years, and the fungi and molds disappear along with the beetles. Drying time can be enhanced by increasing ventilation, e.g., by use of fans and air conditioning. Homeowners can gain some relief with directed applications of aerosol sprays containing pyrethrins, but such treatments would need to be repeated frequently as the beetles continue to emerge. A vacuum cleaner works just as well and removes any visible beetles which are present. Pest control companies may be able to provide additional relief by locating the infested wall areas or source of dampness (usually next to where the beetles are most abundant) and injecting residual aerosols or dusts into cracks and crevices along baseboards and into the wall voids.
If the homeowner can tolerate the beetles during the period when they are most active (late summer) the problem will usually resolve itself. Some comfort can be taken in the fact that foreign grain beetles are only a nuisance by their presence, i.e., they do not bite or damage wood, fabric or stored food in sound condition.
It seems like most years we will see black locust leaves turning brown about this time of the summer. In some years, such as this one, it is quite noticeable. The culprit that typically is causing this unsightly problem is the locust leafminer, Odontota dorsalis. In its adult stage, this insect is a 1/4 inch-long beetle that is brownish-orange with a black stripe down the back and black legs, head and antennae. After overwintering as an adult, the beetles emerge and start feeding on black locust developing foliage, and soon will lay eggs on the undersides of the leaves. Flattened, yellowish-white larvae can be seen tunneling inside the leaves forming a mine that looks like an irregular blotch. After pupating in the mine, adults emerge and begin to skeletonize the undersurface of the leaves and will lay eggs for a second generation. The combined feeding of larvae and adults may destroy much of the foliage and result in seriously stressed trees. Other host plants listed for this beetle include false indigo, bristly locust, Sophora japonica and golden chain tree. Adults will feed on a variety of foliage including dogwood, elm, oak, beech, cherry, wisteria, hawthorn as well as several herbaceous plants. If control measures are needed, a variety of insecticides are labeled for this pest, including Dursban, Lindane, and Talstar. Timing is important to control the adults and larvae before they enter the leaves.
IR-4 is available to help growers of minor use crops have access to safe and effective pest control tools. IR-4's goals are to assist in new registration of reduced risk pesticides on minor crops and facilitate reduced risk use patterns for existing registrations. IR-4 will also support biologically-based pesticides and pesticides essential to IPM systems. For additional information contact IR-4 National Director, IR-4 Headquarters, Cook/NJAES, PO Box 231, New Brunswick, NJ 08903-0231, Telephone (908) 932-9575, FAX (908) 932-8481.
Bayer Corporation and Valent USA, the sole U.S. registrants of the insecticide/miticide methamidophos, have requested that their registations for methamidophos be terminated except for use on COTTON, POTATOES, and TOMATOES. These amendments to the registrants labels will be effective on 12/29/97, unless the USEPA publishes a notice in the Federal Register modifying this proposed order. This action was taken because of estimated occupational risks to agricultural workers and acute worker exposure incidents associated with methamidophos use. The registrants are taking these measures to mitigate risks before the end of reregistation which is expected in 1999 for methamidophos. The agricultural sites affected are as follows:
REGISTERED USES SUPPORTED by Bayer and Valent which are expected to be reregistered:
REGISTERED USES UNSUPPORTED and expected to be DELETED:
*SLN = Special Local Need or 24(c) in the indicated state(s)
After 12/31/97, methamidophos registrants, distributors, and dealers may not sell or distribute existing stocks of products labeled with deleted uses. End users may use existing stocks until such stocks are exhausted. Comments, labeled with the docket number OPP-64033, should be sent by postal or email to the Public Information Branch of EPA by 8/1/97.
| For product information: | For registration information: |
|---|---|
| Dr. Jim Kunstman | Mr. Jeff Morris |
| Bayer Corporation | EPA, Special Review Branch |
| PHONE 816-242-2838 | PHONE 703-308-8029 |
| FAX 816-242-2738 | FAX 703-308-8041 |
| jim.kunstman.b@bayer.com | morris.jeff@epamail.epa.gov= |
Send written comments to: Public Information Branch (7506C), EPA, Office of Pesticide Programs, 401 M Street, SW, Washington, DC 20460;