by William Nesmith
At least some read my article, based on inquires about the article entitled, "1997 Tobacco Blue Mold Experimental Fungicide Trail - Robinson Substation, Quicksand, Kentucky" published in error in the August 25 edition of Kentucky Pest News. We apologize for this mistake. The table published was being prepared for the blue mold field day event advertised in the issue, and was not intended for publication at this time. An article is planned for later this fall to summarize the blue mold experiments being conducted on fungicide application and experimental fungicides at the Robinson Substation.
by William Nesmith
A blue mold watch is in effect statewide. Strong blue mold activity has been occurring in most regions of Kentucky during the past 10 days on unprotected crops that have experienced rapid growth. Leaf vein strikes (limited systemic infections) have accounted for serious leaf damage in mid-stalk and upper leaves in some areas. In some communities, the strongest blue mold activity of the season has been occurring. Properly applied fungicide sprays will provide the best protection against blue mold in crops not yet topped. At topping be sure to include a MH-containing sucker control agent. The benefits from high pressure fungicide sprays become more obvious as canopy closes, because of improved cover on the portions of the leaf nearest the stem. DO NOT MIX MH AND ACROBAT MZ. We have seen some very serious damage from combined applications of the two materials.
We have received numerous calls about strong blue mold activity in tobacco that has been topped for a week. The question is, should I spray with Acrobat MZ? Properly applied, Acrobat MZ will improve blue mold control, but we need to respect the 30-day-waiting-interval between last application and harvest. Violations of the waiting interval will lead to residue problems, based on our lab data.
The emergency exemption for use of Acrobat MZ in Kentucky tobacco fields expires on September 30.
by Paul Vincelli
Stenocarpella ear rot, formerly known as Diplodia ear rot, has become more common in recent years. Often, producers are not aware of the presence of the disease until combining. This ear rot appears as white cottony fungal growth between kernels, progressing from the ear shank upward and from the cob outward. Severely affected ears can be obvious from a distance, as they can turn brown and dry down well before the rest of the plant. Laboratory confirmation recommended if there is any uncertainty as to the ear rot present, since several ear rot diseases can be associated with high levels of mycotoxins.
Stenocarpella ear rot appears to be increasing in importance in several regions. Based on published research on this disease, the increase in prevalence is most likely related to increasing use of conservation tillage. The fungus survives in corn residue left on the soil surface.
Thus far, I have not seen a single ear with the disease, including a visit to a field that was severely diseased last year. I am hopeful that this will be a light year for Stenocarpella ear rot. Dry weather through silking, like many areas experienced, would certainly lower disease pressure substantially.
Keep an eye out for the disease, as harvest approaches. If growing continuous, no-till corn, be sure to have records of fields where the disease shows up at incidences of 3-5% or more. Returning to those fields with corn next year may be risky, if weather favors disease development, since spores levels may have built up this season to dangerous levels in those fields.
A UK Extension publication on Stenocarpella ear rot is in near completion and hopefully will be available to county Extension offices this autumn.
by Don Hershman
Many farmers are seeing one or both of the following diseases develop: stem canker and sudden death syndrome (SDS).
Both SDS and stem canker have similar foliar symptoms in that the tissue between the veins die and the veins (at least temporarily) remain green. The key difference between the two diseases can be seen early or very late in foliar symptom expression. Early on, SDS appears as chlorotic blotches of various sizes and shapes between the veins. Stem canker, on the other hand, develops more like a nutrient deficiency symptom in that the all the leaf tissue between the veins begins to turn yellow at one time; blotches are not apparent. Late in symptom expression, affected leaflets from plants with SDS will drop to the ground, but the leaf petioles will often remain attached. Leaves from plants affected by stem canker will usually remain attached to the plant and just die and dry up. This gives the field a sort of "freeze dried" appearance.
Another obvious symptom difference occurs on the stem. Plants with SDS will have green stems but will be discolored (gray-brown) inside. Stems affected by stem canker will have small to large, dark brown stem cankers visible on the stem surface. Smaller cankers are often associated with stem nodes. When infections kill plants, stem cankers can be extensive, often running the length of the stem. In those cases the entire inside of the stem is often completely deterioriated.
As far as the roots are concerned, plants with SDS will have severely rotted roots; SDS, after all, is a root and crown rot disease and foliar symptoms are caused by a foliar toxin produced by the causal fungus. Plants with stem canker typically have a healthy root system, at least until the final stages of plant demise.
Most of the fields currently expressing level of SDS are early planted beans. In these fields the SDS is moderate and the pods of plants are filled. Thus, I expect to see little yield loss caused by SDS. In fact, SDS must be severe during early-to mid-pod development to have much affect on yield. Fortunately, most years, SDS comes in too late to seriously hurt yields.
Stem canker is a different story. Most of the plants I have seen with stem canker will have serious compromised yields. Stem canker infection occurs during the early vegetative growth stages,as long as wet conditions exist and infectious spores are available. Once infection takes place, the fungus goes dormant until the plant enters the reproductive stages. At that time the fungus breaks dormancy and stem cankers develop. More times than not these stem cankers result in the death of highly susceptible varieties during the critical stages of pod development.
It is very important to distinguish between stem canker and SDS,since soybean varieties differ widely as to their susceptibility to the two diseases. Farmers wishing to avoid both diseases have various options, but planting resistant varieties is at the top of the list. Other practices, such as planting multiple varieties to spread risk, using different planting dates, practicing crop rotation, among others, can also make a big difference in the levels of disease that develop.
More information on both of these diseases can be obtained through your local county Extension office.
by Doug Johnson
There are still a considerable number of grasshoppers around most soybean fields. While these fields do not appear to be in any immediate danger they should be watched. Normally, grasshoppers are only going to be a problem in late season under drought conditions. In most areas enough rain has fallen to bote allow soybean to continue to grow and to keep the grasshoppers happy with other plants. If however, your fields are suffering drought conditions, grasshoppers are abundant and your plants still have the potential to fill pods -- keep your eyes open. These hopper populations will decline as time goes by but will not go away until late fall. If you feel that you have a problem use the defoliation tables in ENT-13 to make your management decisions. Control should not be a problem provided good coverage is obtained.
by Doug Johnson
This nice September weather is just right for Sorghum webworm. If you have grain Sorghum (Milo) that is still younger than hard dough, you should be scouting for this pest. It is often found in mixed populations with the corn ear worm and possibly fall army worm. All of these insects are present in Kentucky's sorghum growing areas now. The only real question is do you have plants in the correct stage. The insects are easy to identify just look for caterpillars feeding in the grain heads. The fuzzy one making a great mess is the sorghum webworm. The yellowish green one with few hairs is the corn earworm. If the worm is very dark and has a pinkish strip down each side you may have Fall armyworm (FAW). You should consider control if two or more (of any combination) caterpillars are found feeding in each head.
You might also find FAW feeding on the leaf tissue, just as they do in corn. Usually by this time of year that will not do much damage. However, if your Milo is excessively late and has not yet headed you best watch out for FAW as they can appear in VERY large numbers and do extensive damage. Unlike in corn, suitable control is usually possible IF the infestation is found before the damage is done. Check ENT-24 for control recommendations.
by William Nesmith
Widely scattered but strong downy mildew activity has been occurring recently in pumpkins, winter squash, and yellow summer squash throughout Kentucky. Most of the reported cases were noticed between August 20 and September 3. Because fungicide spray programs were weak or absent, serious losses often had already occurred by the time the grower noticed the problem. In some cases the growers were spraying Bayleton, Benlate, or Nova (the last of which is not labeled) for powdery mildew, but were not using a general fungicide such as chlorothalonil or mancozeb. Using systemic fungicides alone for powdery mildew control in Kentucky is not wise, because other diseases threaten. In several other cases no preventive spray program had been used at all, and powdery mildew had been active for several weeks.
The spread of a downy mildew epidemic in cucurbits is clearly illustrated by the following growers comments: "It looks like a no-till herbicide has been sprayed out here. On August 25 I had an excellent crop, and within a week my pumpkin patch has gone to nothing but stems." By the way, he had been alternating Bayleton and Topsin M weekly for powdery mildew control, but in previous years had been using Bravo plus Bayleton.
Under ideal weather conditions, downy mildew of cucurbits can cause great damage in a few days. When conditions are favorable for blue mold of tobacco in the community (another downy mildew), they are also favorable for downy mildew of cucurbits. That is why our recommendations suggest you use tobacco blue mold advisories in your area as downy mildew advisories on cucurbit crops, especially in late summer. However, downy mildew in cucurbits operate even faster than tobacco blue mold, because the cucurbit pathogen also produces swimming spores from the airborne spores that land on the leaf. Downy mildew of cucurbits occurs less frequently in Kentucky, because large populations of the host plants are usually not around to support the disease build-up. However, as Kentucky growers increase their plantings of late summer and fall cucurbits, and use more greenhouse-produced plants, they need to expect increased downy mildew epidemics.
Both vegetable and tobacco farmers have been surprised with the drought to see such strong downy mildew activity during late August and early September. However, one or two rains to push new growth and high nighttime moisture are the keys. The Ohio Valley often experiences high daytime humidities in August, which develop into heavy to patchy fogs. When there is fog with cool nights in late summer (temperatures in the 60's), expect downy mildew to operate and prepare accordingly.
First symptoms of downy mildew in cucurbits are of yellowish, irregular to circular spots on the leaf that quickly scald or turn brown in hot weather. A blue to gray fungus (mildew) can be found on the bottom side of the leaf early in the morning and while the lesions are young. The downy mildews can quickly destroy the foliage of members of the cucurbits, usually developing from the center of the plant towards the new growth. The disease can go from infection to symptoms and sporulation in 4 days under the temperature regimes experienced in Kentucky during the past two weeks. A regular preventative spray program with Bravo, maneb/mancozeb, or copper is needed to suppress development of downy mildews in fall plantings of commercial cucurbits in Kentucky. Once downy mildew appears or if Tobacco Blue Mold Watches/Warnings are issued, immediately shift the program to include Ridomil/Bravo, Ridomil/Copper, or Aliette on a biweekly schedule, with the protectant fungicide being used during the alternate week. By the way, also keep the systemic fungicides for powdery mildew control in place (Bayleton, Benlate, or Topsin). See ID- 36 - Commercial Vegetable Crops Recommendation - for more specifics.
by Mike Potter
If you haven't already begun receiving calls about yellowjackets, brace yourself -- you will shortly. During late-summer and fall, yellowjacket colonies are nearing maturity and huge numbers of workers are out foraging for food for the developing queens. With insect prey (their usual diet) becoming scarce, yellowjackets scavenge widely for other sources of nutrition. They're particularly fond of sweets, e.g., fruit, ice cream, beer and soft drinks, but will also feed on meats, potato salad, just about anything we eat. The persistent foraging of yellowjackets at picnics and other outdoor activities prompts many calls from homeowners and businesses, wanting to know what can be done to alleviate the problem. Here are their options:
1. Sanitation - The best way to reduce the threat of foraging yellowjackets is to minimize attractive food sources. People eating outdoors should keep food and beverages covered until ready to be eaten. Spills and leftovers should be cleaned up promptly. Trash cans should be equipped with tight-fitting (preferably self- closing) lids. Similar sanitation recommendations should be made to commercial establishments, including ice cream parlors, outdoor cafes, and produce stands. Whenever possible, trash cans and dumpsters should be located away from serving tables, doors, and other "high-traffic" areas. Trash cans should be equipped with a plastic liner and emptied and cleaned frequently.
Maintaining high levels of sanitation throughout the summer will make areas less attractive to yellowjackets later in the fall. This strategy is especially useful for parks and other outdoor recreation areas. Apples and other fallen tree fruits should be raked up and discarded.
2. Avoidance - Combined with sanitation, avoidance is the best advice in most situations. Yellowjackets foraging away from their nests are seldom aggressive and usually will not sting unless provoked. People should resist the temptation to "swat" at the wasps; most stings occur when foragers are slapped or trapped against skin. Also be careful when drinking from beverage cans into which a foraging yellowjacket may have crawled.
Avoidance may also be the best advice if a yellowjacket or hornet nest is located in a tree or other out-of-the- way location. Yellowjacket colonies die off on their own in late autumn with the onset of cold weather. Abandoned nests are not reused and soon disintegrate.
3. Repellents - A dilute solution of ammonia and water (approximately 6 oz of ammonia per gallon of water) sprayed in and around trash cans and sponged onto outdoor tables and food preparation surfaces may help to repel yellowjackets from these areas. Use household ammonia, not Clorox (bleach).
4. Traps - Although only of marginal benefit, traps are available which catch impressive numbers of yellowjackets when properly baited and positioned (generally around the outer perimeter of the area you wish to protect). Business establishments such as outdoor cafes may find such traps worthwhile when used in conjunction with sanitation and other approaches. Braunswagger liverwurst spread used in conjunction with jelly has been an effective attractant.
5. Insecticides - Elimination of yellowjackets is best accomplished by locating and destroying the nests. However, with foraging yellowjackets this is often impractical since the nest, or nests, may be located several hundred yards away. People should still inspect the area around their homes for nests. The best time to do this is during the daytime, when yellowjackets are entering and exiting the nest opening.
If the nest entrance can be located (typically under- ground in an abandoned rodent burrow, beneath rocks or landscape timbers, or in a stone wall or wall of a building), it often can be eliminated by carefully applying a wasp aerosol insecticide into the nest opening. Insecticidal dust formulations, e.g., carbaryl (Sevin), bendiocarb (Ficam), Drione, etc., are especially effective provided a hand duster or similar type application device is used to dispense several puffs of the dust into the nest opening. A dry, empty liquid detergent bottle filled no more than halfway with dust and shaken before dispensing works fairly well in lieu of a commercial duster. A few pebbles or marbles added to the bottom of the bottle prevents the dust from caking.
Treatment should be performed late at night, when most of the yellowjackets are in the nest and less active. Pinpoint the nest opening during the daytime, so you will remember where to direct your treatment after dark. Approach the nest slowly and do not shine the beam of your flashlight directly into the nest entrance as this may startle the wasps; instead, cast the beam to the side to illuminate the nest indirectly. If possible, place the light on the ground rather than in your hand. As with hornets, yellowjackets are extremely aggressive when the nest is disturbed. It may be prudent to refer homeowners to a pest control operator, particularly when access to the nest is difficult.
Wasp, hornet and yellowjacket stings can be life-threatening to persons who are allergic to the venom. People who develop massive swelling, hives, dizziness, difficulty breathing or swallowing, wheezing, or similar symptoms of allergic reaction should seek medical attention immediately. Itching, pain and localized swelling can be somewhat reduced with antihistamines and an ice pack.
by Monte P. Johnson
The Environmental Protection Agency (EPA) has announced its schedule for reassessing tolerances for pesticide residues in or on raw and processed foods as required by the Food Quality Protection Act (FQPA). Under this new law (enacted 8/3/96), the EPA is required to reassess all existing tolerances and exemptions from tolerances (almost 10,000) for both active and inert ingredients. In reassessing tolerances, the EPA must consider the aggregate exposure to the pesticide; cumulative effects from other pesticides with a common mode of toxicity; whether there is an increased susceptibility from exposure to the pesticide to infants and children; and whether the pesticide produces an effect in humans similar to an effect produced by a naturally occurring estrogen or other endocrine effects.
In its review of these tolerances and exemptions, the EPA must meet the following time table: 33 percent of applicable tolerances and exemptions must be reviewed by August 1999, 66 percent by August 2002, and 100 percent by August 2006. FQPA also required that by 8/3/97, the EPA publish a schedule of its reassessment of these tolerances and exemptions.
The list is too voluminous for publication here, but it can be reviewed by consulting the Federal Register (reference below), EPA's web site at www.epa.gov, or by requesting a copy from Jeff Morris at EPA or this office at USDA. Additional materials on tolerance reassessment may also be found on EPA's web site. In all, there are a total of 469 pesticides or EPA classified high-hazard inert ingredients with food use tolerances scheduled for reassessment. Also, an additional 823 inert ingredient exemptions will be dealt with toward the end of the reassessment of tolerances.
The list has been broken into three groups. Group 1 is made up of chemicals in pesticide products that appear to pose the highest risk. It includes the organophosphate, carbamate, and organochlorine classes, and probable and some possible human carcinogens (materials that potentially cause cancer). Also included are EPA classified high-hazard inert ingredients, any pesticides that exceed their reference dose, and any tolerance that is being proposed for revocation. Group 2 is comprised of possible human carcinogens not included in Group 1, all remaining pesticides subject to reregistration, and others based on scheduling considerations. Group 3 contains biological pesticides, those inert ingredients not dealt with in Group 1, and those post-1984 pesticides with tolerances or exemptions not yet reassessed under FQPA.
For additional information:
Mr. Jeff Morris
EPA, Special Review Branch
Phone 703-308-8029
Fax 703-308-8041
morris.jeffrey@epamail.epa.gov
Send comments to Jeff Morris and:
Public Information Branch (7506C)
EPA, Office of Pesticide Programs
401 M Street, SW
Washington, DC 20460
opp-docket@epamail.epa.gov
(Source: Federal Register 62:42019-42030 8/4/97;
Reregistraton Notification Network, 8/18/97)
by Monte P. Johnson
Since last year, the Environmental Protection Agency (EPA) has been making an effort to improve the readability and effectiveness of information printed on pesticide labels and labeling. In implementing the Consumer Labeling Initiative (CLI), the EPA has convened a workgroup of stakeholders including consumer product manufacturers, trade associations, public interest groups, health and safety officials, market research specialists and individual citizens. The CLI conducted a series of one-on-one interviews with consumers across the country to examine how they read product labels, what they found to be useful information, and what they found confusing. As a result, one section of labels that will most likely be revised will be the "Statement of Practical Treatment" portion. It most likely will be renamed "First Aid" and will have more specific information, shorter sentences, bullet points to attract attention, and will TELL people what to do. (EPA, August 21, 1997).
by Julie Beale and Paul Bachi
We have seen a number of cases of sudden death syndrome (Fusarium) and stem canker (Diaporthe) of soybean recently. On tobacco, physiological leaf spots are common. These small, pale, papery spots may be weather-flecking from ozone, hypersensitive reaction to blue mold may be the result of root/environmental stresses, or, as in most cases, may be a response to virus infection. The aphid-borne virus complex (which includes tobacco etch virus, tobacco vein mottling virus and potato virus Y) is widespread; tobacco ringspot virus, tobacco streak virus, and impatiens necrotic spot virus have also been diagnosed. Often, brown spot (Alternaria), frogeye (Cercospora) and angular leaf spot (Pseudomonas) colonize leaf tissues weakened by virus or other problems. We have also seen cases of frenching, false broomrape (indicating hostile soil environment) blue mold, black shank, soreshin and root knot nematode on tobacco.
On ornamentals, Phyllosticta leaf spot on English ivy, Cercospoa leaf spot on azalea, scale insect on euonymus, and lacebug injury on oak were diagnosed. Vegetable problems have included downy mildew on pumpkin and watermelon, gummy stem blight on cantaloupe, Fusarium crown and stem rot on basil, uneven ripening (physiological) and walnut wilt on tomato.