Kentucky Pest News Newsletter


Number 1028__________July 6, 2004


Ky Blue Mold


By William Nesmith

Tobacco If blue mold is active in your county and we do not have your county in the active list below, please let the local county extension office know.

Blue mold continues to build in Kentucky (at epidemic levels in some areas) concentrated along the general southwest to northeast corridor mentioned in the previous reports. However, the southern base is now established widely, as far east as western Virginia. Much stronger activity should develop in southern and southeastern Kentucky, especially in the more lush crops that have recently closed their canopy. Expect the level of activity to build very rapidly in central and northern Kentucky, and southern Ohio where the disease is well established. Blue mold is rapidly building to epidemic levels in some communities and serious crop damage has already occurred on many farms.

A blue mold advisory exists for the entire burley production area, with watches for the eastern two-thirds of Kentucky, southern Ohio, and western West Virginia. Based on weather events this past weekend in the region, I believe viable blue mold spores were also moved north-northwest, in addition to the normal movement with the prevailing winds. Consequently, I have expanded the watch area to now also include Meade and Breckinridge counties in Kentucky, and Harrison, Floyd, Clark, Jefferson, Switzerland, Ohio, and Scott counties in southeastern Indiana. Massive new sporulation was occurring every morning this past week in central Kentucky. Warnings exist for all counties with confirmed cases of blue mold. However, we have reduced the area of western Kentucky under a watch (from a watch to an advisory), as evidence of westward movement of new blue mold has not been found. It is very important that any appearance of blue mold in western Kentucky be promptly reported so growers can respond. The higher night temperatures have probably been a key factor in reducing strong establishment in the west.

Blue mold is causing considerable crop damage in some areas. In some fields the leaf yellowing from systemic-leaf infections in the lower leaves is so common that growers think their crop has run out of nitrogen. Mike Carter, County Extension Agent in Garrard County, Kentucky filed the following weekly report. "Blue mold is currently more widespread and, in my opinion, is doing more damage to our burley crop in Garrard County than at anytime in any previous year - and I was here before field blue mold and saw the great epidemics of 1979 and 1996. Most every field is experiencing the fungus regardless of any mefenoxam use history, so I conclude our strain is not mefenoxam-sensitive. Many growers are not attempting to control the disease, and some are waiting until the crop is hurt to attempt controls, but others are making an honest effort to prevent it or get controls in place very early in the out break. They are using Acrobat MZ and Actigard. Where timely treatments are being made with these products we are seeing success, so far. Black shank is also showing up in a lot of fields, as well. "

Most areas are not seeing much difference in the level of blue mold activity in mefenoxam (Ridomil Gold or Ultra Flourish) treated fields as compared to untreated strips, but some are seeing very clear differences. Where the mefenoxam-sensitive population is operating, growers are urged to use the soil- direct cultivation and layby treatments to control blue mold. These products are not labeled for foliar use, in fact the label prohibits foliar use. Mefenoxam should be the most effective option in communities where the sensitive population dominates, but the resistant strain is already or soon will be present, too, so mefenoxam alone will not be adequate for most cases.

Here is an account from Michael Duckworth, County Extension Agent in Woodford County, Kentucky (a nearby county to Garrard) to help illustrate this point: "I have surveyed over 100 acres of tobacco in Woodford County making careful observations in fields with and without blue mold and to what treatments growers have used. Tobacco fields examined that have been treated with mefenoxam (Ridomil Gold here) at planting are doing well. However, untreated fields are showing severe damage from blue mold. We are now seeing some activity in fields where low rates were used and growers have not used a supplemental Ridomil Gold application. Most of the wel-managed fields have at least one treatment of Actigard and several growers are making the second treatment. The strong, sporulating blue mold is mainly on untreated fields at this point, however it is starting to show on fields where only low rates of Ridomil Gold were used. We have also noticed that where growers transplanted systemically infected plants into Ridomil Gold treated soil, there appears to have been no control - such plants are just not growing."

As of press time on July 6, counties with one or more confirmed cases of blue mold included:

Several dealers have reported, and Syngenta representatives have confirmed, that supplies of Actigard 50 W (the plant inducer) are limited in the burley region. Efforts are underway to locate and redistribute some stocks allocated to other areas. Communities that order early are not experiencing shortages to date. Their representative has asked that we remind all of the new label for Actigard 50 W, which allows up to three applications.

In Transplant Operations - Most of the crop has been set, but attention is still needed for the few remaining plants. Keep fungicide sprays applied for good coverage and as often as labels will allow. The labeled fungicides for use in transplant systems can be found in the March 8, 2004 issue of Kentucky Pest New, . Remember our recommendations all season have been: " Because tobacco transplant production systems are so conducive to blue mold development, should even small amounts of inoculum arrive, we recommend that all tobacco transplant production systems should be managed to minimize leaf wetness and regular preventive fungicide sprays should be maintained. Once fungicide sprays have been stopped the remaining transplants should be destroyed to prevent the abandoned plants from serving as an ideal staging area and source of inoculum for blue mold. "

In the field- Cultural practices that assist in blue mold control include: using blue mold tolerant or resistant varieties in conducive sites, setting blue mold-free transplants, reducing plant populations, avoiding high nitrogen rates, avoiding shade (especially from the south and west), maintaining good air circulation in and around the field, and destroying all unused transplants, promptly. Taking steps to improve air movement around fields by keeping field edges and fence rows well mowed can be helpful under the weather conditions being experienced.

Foliar fungicide sprays can be very helpful in blue mold management if applied regularly and well. Soil applied Ridomil Gold or Ultra Flourish can also be very helpful where mefenoxam-sensitive strains are operating. Guidelines for using labeled products can be found in the April 26, 2004 issue of Kentucky Pest News:

Information on tank-mixing Acrobat 50 WP and Dithane DF Rainshield is presented in the June 1, 2004 issue;

For information on the performance of the labeled products (Acrobat MZ and Actigard 50WP) during the 2003 epidemic see the March 22, 2004 issue of Kentucky Pest News at .

For performance during the 2000 epidemic see June 4, 2001 issue of Kentucky Pest News ( there is an error in the market values for that table due to using the wrong multiplier, but all the other data for disease and yield are correct as collected) at .

For data on the economic value of using foliar fungicide sprays under various levels of blue mold pressure see the June 1, 1998 issue of Kentucky Pest News at .

And, for evaluation of high pressure spraying in blue mold control see the November 3, 1997 issue of Kentucky Pest News


For the latest blue mold status and other tobacco disease information, check the KY Blue Mold Warning System online.
Blue Mold

For more information about tobacco pests, visit "Insect Management Recommendations".



By Doug Johnson

Jap beetle We are perhaps at the height of Japanese beetle season in Kentucky. Their feeding on soybeans should be obvious across the state. Certainly in western Kentucky they are easy to find. Infestations of this insect are often quite dramatic but seldom of economic importance.

The Japanese beetle has been migrating across the state for years. As it reaches new territory each year, the combination of being new and in very large numbers often persuades growers that a devastating infestation is occurring. As the years pass the natural predators (especially birds), parasitoids and diseases become active on this pest and the overall numbers decline. They will probably never go away completely but they will not remain in the large numbers that the first occurrence brings.

The visual impact of this pest feeding on soybeans is twofold. First it skeletonizes the upper leaves on the plant leaving them looking like they are heavily damaged. Second, they appear in very large numbers, and tend to fly around causing people to notice them. They tend to be much more obvious on the field edges, and their distribution across the field will be clumped. In addition, it is not unusual to find them active in one field and almost absent in an adjacent field. Japanese beetle infestations are a lot like bleeding; a little blood looks like a whole lot!

In general Japanese beetle will not do economic damage to the crop. Certainly they can, and should be watched, but most often they just serve to get the blood pressure up. One should use defoliation tables to decide if sufficient damage is being done to warrant an application of insecticide. When you try to determine the level of defoliation in your fields do not be tricked into looking at only the damaged area of the plants. This is what often gets a field sprayed that should not be. Check the whole plant. Soybeans have a tremendous ability to compensate for damage, especially if they are still putting on leaves.

Defoliation tables can be found in: IPM Scouting Manual for Soybeans (

If you find that an insecticide application is warranted, the beetles are not difficult to kill. Check the Insecticide Recommendations for Soybean (ENT-13). You can find them on the web at:

You can always get a printed copy of these and other publications from your local County Extension office. To find one near you look at:

For more information about soybean pests, visit "Insect Management Recommendations".



By John Hartman

Rhododendrons are sold in garden centers and grown in nurseries and landscapes throughout Kentucky. Despite fairly fastidious growing requirements such as a need for moist, but not wet, acid soil; screening from the hot sun; and shelter from cold, cutting winds, they are popular with many gardeners.

The U.K. plant pathology department is engaged in the current Kentucky survey for Phytophthora ramorum, cause of sudden oak death. As part of this survey, rhododendrons are commonly submitted for assay for this pathogen. Although it is one of many species susceptible to this pathogen, P. ramorum has not been found on rhododendrons here, fortunately. However, several diseases and disorders are being observed on rhododendron samples examined in our laboratory. As can be seen from this list, if adverse growing conditions don't directly cause decline, they favor many of the diseases commonly found on rhododendrons.

Phytophthora dieback. This disease is appearing most commonly in survey samples. Wet spring weather with frequent rains these past two years may have favored this disease. In addition, symptoms of Phytophthora dieback most closely resemble potential P. ramorum symptoms and samples with these symptoms are more frequently collected. Several species of Phytophthora have been implicated in this disease. The Phytophthora fungi that invade the twigs and stems also invade the leaf petioles and leaves. The brown leaf lesions are unique for this disease. Phythphthora dieback can be confused with leaf blights, leaf spots, and dieback and canker diseases.

Gray blight. Leaf blight, caused by Pestalotia spp., appears as gray lesions with brown margins. As the lesions expand and cover the leaf, defoliation may result. Dark pimple-like pycnidia of the fungus may appear embedded in the diseased leaf tissue. The gray blight fungi are regarded as weak parasites, invading leaf tissues that have been injured by sunscald or winter cold. Gray blight appears quite frequently in this survey and in most cases does appear to be associated with abiotic injuries.

Discula leaf spot. This disease, with leaf spot and blight symptoms similar to anthracnose on other host plants, is appearing in the survey. Look for tiny dark fungal fruiting structures, visible with a hand lens, in the diseased leaf tissue. This disease is also favored by wet spring weather.

Phyllosticta leaf spot. Caused by Phyllosticta sp., symptoms on rhododendrons consist of small spots with tiny black fungal fruiting bodies. This seems to be a fairly minor disease appearing in the survey.

Powdery mildew. Powdery mildew disease is easily recognized by the white, powdery signs of the causal fungus, Microsphaera azaleae, and possibly other species on the surface of the infected leaves. Young plants are most vulnerable to the disease, especially those grown in the shade. This disease is not appearing much in the survey except when parts of leaves become necrotic after prolonged and severe infection and laboratory diagnosis is needed.

Botryosphaeria dieback. Dieback and canker, caused by the fungus Botryosphaeria dothidea, is often found on individual rhododendron branches. The first indication of a problem usually is the appearance of individual stems with drooping leaves that are rolled inward. Closer examination of affected stems reveals a reddish-brown to black sunken canker that girdles the stem. Cankers develop slowly and may appear a month or two after infection of a pruning wound, an injury, or a leaf scar. This disease is more likely to occur on plants suffering from heat and drought stress or winter injury. Pruning tools have been implicated in spread of the fungal spores.

Phomopsis dieback. In the survey, a species of the fungus Phomopsis has been observed. This fungus causes canker and dieback symptoms similar to those of Botryosphaeria dieback.

Phytophthora Root and Crown Rot. Phytophthora cinnamomi, P. cactorum, P. citricola and other species sometimes cause rhododendrons to decline and die in Kentucky landscapes. This disease is not appearing much in the survey, but the survey is biased towards foliar and shoot pathogens of rhododendrons. However, from years of experience in the Plant Disease Diagnostic Laboratory (not the lab conducting the P. ramorum survey) we know that root and crown rot are fairly common in Kentucky. Examination below ground will reveal a reddish-brown color of decayed roots, and a reddish-brown discoloration of the stem at or just below the soil line. Phytophthora root rots are favored by wet soils. Periodic flooding provides opportunities for the fungus to produce swimming spores which function in disease spread. This disease can attack plants growing in otherwise good growing conditions.

By Lee Townsend

Clusters of the redheaded pine sawfly are feeding now on some Kentucky pines and can defoliate small trees in a short time. They tend to attack trees in the 1 foot to 12 foot height range, especially those already under stress due to poor site or severe competition from other trees. This species attacks longleaf and shortleaf pines.

These distinctive larvae have red heads with 2 black eye spots and a yellow-white body with six rows of black spots. They feed for about four weeks and are 1" to 1-1/4" long when full grown.

There are two generations each year, with the first appearing in early summer. The larvae feed gregariously on new and old needles, as well as the tender bark of young twigs, starting at the top of the tree and moving downward. Orthene or Sevin can be used for control, Bt caterpillar sprays do not work against sawflies.



By Lee Townsend

Mosquito The first equine case of West Nile virus (WNV) in Kentucky (Nelson County) was reported last week by the Kentucky Cabinet for Health Services - Department for Public Health. When combined with the previous bird cases, the total WNV cases for 2004 now stands at three. Horses are particularly susceptible to encephalitis (inflammation of the brain) caused by the WNV. This virus can be picked up by any one of several mosquito species that feed on infected birds. These mosquitoes then carry the virus particles in their salivary glands and can infect susceptible hosts - healthy birds, other animals, or humans - when they feed again. Horses, humans, and most other animals are considered to be "dead end" hosts. They can become infected but do not develop a high enough level of the virus to infect other mosquitoes.

What can be done to reduce mosquito problems on horse farms?

For more information livestock pests, visit "Insect Management Recommendations".



By Julie Beale and Paul Bachi

The Diagnostic labs have been piled high with samples during the past week, especially tobacco. We have seen numerous cases of black shank and blue mold, as well as more frogeye leaf spot than we would normally see this early in the season. Target spot is also beginning to develop extensively in some fields. We have also seen angular leaf spot, blackleg, black root rot, Pythium root rot, tobacco ringspot virus, alfalfa mosaic virus, tomato spotted wilt virus, wet weather frenching, acid soil problems including manganese toxicity and nitrogen, potash and phosphorus deficiencies, and weather fleck (ozone).

On fruits and vegetables, we have diagnosed anthracnose, black rot and phylloxera injury on grape; anthracnose and double blossom (Cercosporella) on blackberry; Phytophthora root rot on raspberry; scab, bitter rot, cedar- apple rust, fireblight and frogeye on apple; brown rot and scab on peach (brown rot also on plum); Phyllosticta leaf spot on pawpaw; bacterial wilt, Alternaria leaf blight, and magnesium deficiency on cantaloupe; southern blight on pepper; and Fusarium wilt, buckeye rot, southern blight, Septoria leaf spot and bacterial canker on tomato.

On ornamentals and turf, we have seen powdery mildew on dahlia; Pythium root rot on Asiatic lily; black root rot on petunia; Exobasidium leaf/flower gall and lacebug injury on azalea; powdery mildew on dogwood and crepe myrtle; decline (abiotic factors) on ornamental pear; anthracnose on maple; Actinopelte leaf spot and jumping oak gall on oak; tip blight on pine; Rhizosphaera needlecast on spruce; and brown patch on fescue.

Scout Cat


By Patty Lucas, University of Kentucky Research Center

UKREC-Princeton, KY, June 25-July 2, 2004
Black Cutworm 3
True Armyworm 28
Corn Earworm 1
European Corn Borer 0
Southwestern Corn Borer 2

To view previous trap counts for Fulton County, Kentucky go to - and click on "Insect Trap Counts".

For information on trap counts in southern Illinois visit the Hines Report at - The Hines Report is posted weekly by Ron Hines, Senior Research Specialist, at the University of Illinois Dixon Springs Agricultural Center

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.

Lee Townsend
Extension Entomologist