First let us dispel a rumor that was spreading rapidly late last week. Blue mold has NOT been found in Fayette County, Kentucky nor anywhere else in Kentucky. The Plant Disease Diagnostic Labs have received several tobacco samples from around the state in which the grower suspected blue mold, however, blue mold was NOT involved in any of those cases.
As of late Friday, April 18, blue mold had not been reported from any commercial tobacco area in the U.S. I communicated directly with Dr. Tom Kucharek, Florida's Blue Mold Coordinator, on Friday and he indicated that no cases of blue mold have been confirmed but they are watching closely following the forecast of April 11-16. The weather events over the southeast during that period materialized as forecasted. This does not mean that automatically blue mold spores were introduced, but it does means that a high-risk situation did occur. Therefore, I recommend that Kentucky producers remain alert to the potential of blue mold in the southeastern transplant production areas.
The only confirmed blue mold activity in the U. S. is that on wild tobacco in Texas. Local conditions in Texas have remained favorable for the disease to remain active and spread locally, but the probability of spread outside the region has been very low during the last two weeks.
After evaluating the final production statistics from the 1996 crop, the estimate of losses from blue mold are put at $165,000,000, down from the $192 million estimated in September 1996. The major reasons for lower estimates are related to the fact that actual losses from blue mold in the Bluegrass and Mammoth Cave regions (two large production regions) were only about half the earlier estimates. Some regions had much higher losses than previously estimated, such as eastern Kentucky and portions of the Lake Cumberland area.
The benefits from using Acrobat MZ under the Emergency Exemption fell well below what they could have been. Use of Acrobat MZ during the 1996 season was estimated as follows:
If the protracted period of rainy weather in the forecast for this week actually materializes, infectious diseases could increase rapidly in tobacco transplant production systems, especially greenhouse and float systems. This situation is aggravated further by the fact that many growers are experiencing problems with over-wet media. As a result, growers should pay particular attention this week to reducing moisture in the greenhouses through proper management of temperature, humidity and ventilation. When temperatures allow, get air movement in the float systems as well. In addition, regular fungicide applications should be made to suppress fungal disease activity. However, growers need to recognize that labeled fungicides alone will not be sufficient to control the expected range of diseases.
Increased humidity and wet foliage for extended periods will favor infections of the stem and leaf by fungi such as Sclerotinia, Rhizoctonia, and Botrytis; plus blue mold, if spores are arriving from the south. Pathogenic bacteria, mainly bacterial soft rot and angular leaf spot, will also be favored by protracted wet conditions, especially in systems being over-fertilized.
At this time of year, wet conditions under cool periods (which will exist in outdoor floats) will favor Sclerotinia and Botrytis while wet conditions during warmer periods (which are likely in greenhouses) will favor Rhizoctonia. Where the soil is also saturated, conditions will favor root infections by Pythium, but with higher humidity in the greenhouse, Pythium can move up into the lower stem and foliage and spread horizontally along the surface.
The only fungicides labeled for use in greenhouses and floats in Kentucky are Carbamate WDG and Dithane DF. In addition, in traditional ground beds, streptomycin (for bacteria) and Ridomil 2E (for Pythium) can be used. Growers are urged to use these materials for disease prevention as labeled. However, remember that Dithane DF can be very phytotoxic to small seedlings and is not labeled for use until plants have dime-size leaves. None of these fungicides will effectively control Sclerotinia and they will only suppress certain stages of Botrytis and Rhizoctonia.
Growers should be very careful with clipping. Clipping should be done to dry plants only and discard the clippings well away from the transplant site.
While some producers may be eager to get there seed in the ground as sound as they can, cools soils may lead to significant insect damage and stand loss. Damage by two insects, the seedcorn maggot and black cutworm, can be more severe in cooler soils. With both these insects, they are able to develop and feed at temperatures below which corn can develop. Seedcorn maggots can develop at 44 F and black cutworm at 48 F, while corn needs 50 F to grow. Soil temperatures hovering between 44 F and 50 F allow for insect injury to occur and prohibit corn from growing out of the vulnerable seed/seedling stage.
Seed corn maggot is a pest favored by early planting dates, heavy cover crops, and cool-wet weather. Seedcorn maggot damages newly planted seeds by feeding on seed contents. Often the shells of the seeds are empty and germination is greatly reduced. Attack is most severe when moist, cool spring conditions contribute to delayed, slow germination and emergence. When stand loss or plant injury due to seedcorn maggot becomes apparent, there are no effective rescue treatments available. Resetting or replanting of crops may be necessary if stand loss is severe.
While seedcorn maggot can severely reduce plant populations, there are a number of other factors that can reduce germination. If seedcorn maggot is suspected, carefully dig up the seeds in the row skips and examine them for evidence of damage.
Crops planted early when the weather is cool and wet for long periods of time are potentially at greater risk to damaging infestations. With this insect, planting in well prepared seedbeds, planted sufficiently late for quick germination is one means for preventing injury. Where possible, heavy cover crops should be turned over early to render the field less attractive to egg laying seedcorn maggot flies in the spring. Egg laying usually occurs for a short period of time just after cover crops are turned over. Occasionally, crops are seeded when soil temperatures are below those for optimal or rapid germination. Shallow planting increases germination rates, aids in speeding up germination and reduces losses to seedcorn maggots. Under these conditions, higher seeding rates should be considered to offset stand loss.
Black cutworm can cause serious damage in a short period of time during periods of cool temperatures. However, preventive treatments are not routinely recommended, because of the likelihood of cutworm problems and the fact that insecticides applied at planting may not provide acceptable control of heavy cutworm infestations, and a rescue treatment may be necessary anyway. Scouting for black cutworm larvae and damage should begin 300 degree-days (using a 51 F base) after the first intense flight. We have been capturing black cutworms for the last three weeks in Lexington and Princeton. A black cutworm degree day model is available through the KY AG Weather Center on the World Wide Web. Keep in mind that pheromone traps alone cannot accurately predict whether or not a given field will have an economic infestation; they indicate only when egg-laying is occurring.
From a disease standpoint, wheat is looking better than average. The main diseases out there are wheat spindle streak mosaic, caused by WSSMV, and speckled leaf blotch, caused by Septoria tritici. Spindle streak symptoms normally disappear by crop flag leaf emergence, but symptoms are hanging on this spring because crop development is ahead of schedule, but temperatures remain cool enough to support symptom expression. Speckled leaf blotch does not appear to be moving much and is mostly in the lower crop canopy, associated with cold damaged tissue. Fields that have been damaged by the recent frosts may be more prone to new infections by S. tritici.
Powdery mildew, which is usually quite evident in many fields by this time, is at extremely low levels. The same holds true for leaf rust. However, reports from the deep south indicate that leaf rust levels are much higher than normal this spring. This means that rust could become a problem at any time. Remember that leaf rust can develop very rapidly in a susceptible crop during warm, wet conditions. For this reason, it is very important to walk your wheat fields in an attempt to keep up with current disease development. Leaf rust is one example where it can quickly become too late to do anything of value to limit yield loss.
Recently an article from a west Kentucky newspaper was brought to my attention by Lincoln Martin, the Fulton County Ag Extension Agent. The article, obtained from the Associated Press and entitled "Researchers battling soybean blight", outlined how researchers from the University of Illinois were addressing the increasingly more severe white mold problem in Illinois.
Earlier this year a crop consultant from Minnesota presented a training to a group of Kentucky soybean farmers and dealers. During that training the consultant stated that we should not grow narrow row soybeans because that practice will increase problems with white mold.
Both of the above situations resulted in my receiving numerous questions from producers and dealers about the status of white mold in Kentucky soybeans. My answer was that the fungus that causes white mold, Sclerotinia sclerotiorum, is widespread in Kentucky, but it IS NOT a problem in soybeans. The reason for this apparent inconsistency has to do with the biology of the fungus and the epidemiology of the disease.
The fungus produces spores in west Kentucky from Late March to mid-May. This aspect of fungus biology was studied by us during 1991-1993. At that time we were interested in canola white mold, but the data turned out to be just as useful for understanding why white mold is a problem in some crops in Kentucky and not others. Also, for serious infection to occur, susceptible crops must be flowering or have otherwise highly susceptible tissue the same time fungal spores are produced. In the case of soybeans, it is the flowers which are initially infected by the spores of S. sclerotiorum. The same is true for canola. The big difference, however, has to do with WHEN those crops flower in Kentucky. Canola flowers are produced the same time as the fungal spores: mid-April to mid-May. This is why white mold is such a serious problem in Canola. Soybeans, on the other hand, do not flower until late June at the earliest. Doublecrop soybeans (almost one- half of our soybean crop) aren't even planted until very late June to early July. The main point is that white mold spores are not available at a time when soybean plants are susceptible in Kentucky.
The situation I just described for Kentucky does not hold true in more northern production areas. In those areas (upper midwest and Canada), the growing season is compressed to where white mold spores and soybean flowers are often present at the same time.
During extremely cool and wet seasons, white mold can seriously hurt crop yields - as much as 50% according to the newspaper article I referred to earlier.
Honeylocust plant bugs are now emerging on honeylocust trees. Feeding by the small, pale green insects causes distortion, stunting and discoloration of the foliage. Leaf damage persists throughout the season. Eggs hatch in April, and the young nymphs attack new leaves as they are expanding. Nymphs transform into adults by mid-May, and lay eggs in woody tissues. Winter is passed in the egg stage.
Control- Damage from honeylocust plant bug rarely endangers tree health, but can be a concern from the standpoint of cosmetics. Early activity is often overlooked and infestations are not recognized until symptoms appear. By this time, control efforts are no longer effective. Nurseries who want to avoid cosmetic damage should examine expanding leaflets for the small, green nymphs and treat while the insects are still active. Insecticidal soap, 2% horticultural oil, or conventional insecticides (e.g., Sevin, Dursban, Tempo, Talstar, Scimitar) are effective. Check the foliage 7 to 10 days after the first treatment to determine whether or not another application is needed. There is only one generation each year.
Fleas are perhaps the most annoying and persistent household pest. Once a home becomes infested, control can be difficult, time-consuming and expensive. A flea-infested dog or cat can introduce hundreds of new flea eggs into the home each day. By mid- to late summer, pet owners often find themselves fighting a losing battle against established flea populations that are enormous.
A better way to manage fleas is through prevention. By acting now -- before fleas are abundant -- pet owners can avoid severe infestations of fleas later in the summer.
Preventive flea control has been made possible by new technology and insights into flea biology. We now know that adult fleas (the biting stage) spend virtually their entire life on the pet, not in the carpet. Eggs are laid on the fur and fall off into carpeting, beneath furniture cushions, and wherever else the pet lays, sleeps or spends time. After hatching, the eggs transform into larvae, pupae, and eventually adults to renew the cycle.
Pet owners can break the flea's life cycle and prevent a massive buildup of developing fleas by killing the eggs as they're laid on the pet. The easiest way to accomplish this is to treat the dog or cat with a long-lasting insect growth regulator (IGR) during the spring, before fleas become active. Two relatively new products -- one a collar and the other a tablet -- are especially effective and convenient to use.
Ovitrol(R) Flea Egg Collar- Unlike conventional flea collars, this one contains the development-inhibiting ingredient, methoprene. It is available through veterinarians for use on both dogs and cats. An identical retail version, the Fleatrol(R) Flea Egg Collar, is sold in pet stores. Once installed, methoprene releases from the collar and rapidly distributes over the fur of the entire animal, killing flea eggs on contact. This breaks the life cycle and infestations never become established. The metho- prene-impregnated collars are virtually 100% effective at preventing new flea eggs from hatching for at least 6 months on dogs, 12 months on cats.
Program(R)-This product also prevents flea eggs from hatching, but is administered orally to pets once a month at mealtime. Dogs are fed Program(R) in tablet form, whereas cats are fed a liquid suspension mixed with their food. Different tablet sizes and suspension doses are prescribed according to the weight of the animal. When a female flea bites a Program(R)-treated cat or dog, the flea ingests the active ingredient (lufenuron) which then passes into her eggs and prevents them from hatching. Program(R) is dispensed only through veterinarians.
The best way to use either the Ovitrol(R)/Fleatrol(R) Flea Egg Collar, or the Program(R) tablets is to begin using them now, before flea season begins. By doing so, you will greatly reduce the chances of developing a serious flea problem later in the summer. Any stray fleas the pet happens to pick up around the home or at the kennel will be unable to lay viable eggs. Breaking the cycle of flea development on the pet also reduces the need to apply insecticides throughout the living areas of the home. (Both of these products are of negligible hazard to people and pets, and there is no adverse reaction with other medications.)
If you were frustrated by fleas last year, give this preventative approach a try. In Kentucky, the treatment regimen need not be maintained beyond November unless fleas continue to be a problem. The above-mentioned products may need to be supplemented periodically with a topical spray or dip to knock down any adult fleas irritating the pet, especially if the animal is flea allergic. Otherwise, these occasional adult fleas will be unable to reproduce and will soon die off. Two new veterinarian-supplied products, Advantage and Frontline, control adult fleas on pets for very long periods (1 and 3 months, respectively), and may actually achieve the same net result as Ovitrol and Program. Always read and follow label directions and the advice of your veterinarian.
| Princeton | |
| Black Cutworm | 0 |
| True Armyworm | 0 |
| European Corn Borer | 0 |