Pesticide Training Meetings
February 15 - Agricultural Pesticide / Pest Management Workshop, Executive Inn
East, Louisville, KY Approved for continuing education credits for commercial
applicators and Certified Crop Advisors
March 16 - IPM Training, UK Research and Education Center, Princeton, KY Approved for continuing education credits for commercial applicators and Certified Crop Advisors
For more opportunities go to http://www.kyagr.com/enviro_out/pesticide/programs/testing/CEUlistAG.htm
Check the new WATCH FOR section for information on arthropod activity that has been reported or is just around the corner.
WATCH FOR:
Insects from stored products (Entfact 612) and firewood (Entfact 626).
Wireworms reports have been on the increase the past few years in many corn fields in Central Kentucky. Wireworms are particularly damaging to corn as the larvae often attack the growing point of the young seedlings and the seedling keep the growing point below ground until stalk formation. Seeds damaged by wireworms fail to produce plants, and seedlings attacked by wireworms often display a characteristic deadheart, where the youngest leaves wilt and die. A deadheart is evidence that either the growing point has been killed or the leaves have become detached from the growing point.
Economic wireworm damage to field crops is becoming more apparent in some areas of the state, and where they are a problem they can be very destructive and difficult to control. Why have they become more of a problem? That is difficult to say, but there are factors that may favor increased damage. One factor is planting date, many growers over the past 10 years or so have been pushing up planting dates for corn. Some do this as they are farming more acres than they used than in the past and need the extra time. Others are trying to capitalize on soil moisture and want to have a mature plant with a well-developed root system prior to the heat of the summer. But early planting of corn may favor wireworm damage. Planting into cool soils slows germination of the seed and seedling growth leaving them vulnerable to attack for greater periods of time. Certain species of wireworms are abundant only in poorly drained soils. The proper draining of such soils will prevent damage by these species.
Because some species of wireworms have extended life cycles, the same wireworms can cause problems year after year in the same field. Some may require five or more years to complete their development. While wireworms are most often a problem in fields that have been in sod for many years, particularly bluegrass sod. We have reports of serious stand loss in fields that have been in corn and soybean for many years. But one fact is true, wireworm treatments must be preventative, there is no effective rescue treatment once symptoms of damage are observed.
Soil insecticides at planting or seed treatments are recommended for corn where the risk of wireworm damage is high or where wireworms damage was observed with the previous crop. There are liquid and granular insecticides registered for wireworm control for many crops. Best results can be expected when the insecticide is placed directly in the seed furrow. Seed treatments have been effective in many situations, but we have also observed early-planted fields with severe wireworm numbers where seed treatments, as well as soil-applied insecticides, failed to provide effective control.
With the threat of Asian soybean rust in 2005, some soybean producers are choosing to substantially reduce planting intentions for soybeans. This likely will mean an increase in the acreage of corn following corn.
Pressure from several corn diseases is increased when corn follows corn, especially under a conservation tillage program. Year in and year out this is true for several important diseases, such as gray leaf spot and Diplodia ear rot. More about the effect of continuous corn on these and other diseases is available in the Extension publication, Diseases of Concern in Continuous Corn, available at http://www.ca.uky.edu/agcollege/plantpathology/PPAExten/PPFShtml/ppfsagc1.htm
Producers should pay attention to these diseases when selecting hybrids with suitable levels of disease resistance for 2005. In addition, because of the unusually high levels of Northern leaf blight in 2004 in many areas of Kentucky, producers should consider the levels of resistance to this disease, as well. Like the fungi that cause gray leaf spot and Diplodia ear rot, the fungus that causes Northern leaf blight of corn overwinters in infested corn residue, so reduced-till continuous corn has a higher risk than a rotated field, and inoculum levels are likely to be higher in 2005 than normal. More information on Northern leaf blight can be found in several Kentucky Pest News issues published in November, 2004 through January, 2005.
For information about corn pests, visit
"Insect Management Recommendations".
This year brings us the fifth season for dealing with the soybean aphid. The past four years have brought relatively little impact for Kentucky other than learning about and watching for the beast. Hopefully, the 2005 season will be just as uneventful; however, several recent occurrences will make this year somewhat different.
Large 04 Fall Populations Colonizing the Primary Host. Perhaps the biggest single difference in 2005 from other years is the likelihood that very large populations of soybean aphid may be available to start this season. For several years Dr. David Voegtlin (Illinois Natural History Survey) and coworkers have been working on methods of predicting aphid population size. It appears that the number of aphids, as caught in aphid traps, returning to colonize their primary host for over-wintering may be the best indicator. This past fall (2004) very large numbers of aphid migrants were captured. So, based on the three previous years experience, we expect to see larger populations in the 2005 season.
Effect of Controlling Soybean Rust on Soybean Aphid Populations. Without question, understanding soybean rust will be among the highest priorities for KY soybean producers in 2005. Certainly, control of this fungal pest could be an important effort. However, don't forget that what you do to control soybean rust could affect soybean aphid populations. The fungicides that control soybean rust will also suppress the fungal diseases of insects. This could allow for larger soybean aphid populations as one of their natural controls is suppressed. In addition, adding unneeded insecticides, applied at inappropriate times, will further suppress biological controls of soybean aphid and other insects. This will all become much more important if soybean rust treatment is widespread. If you must apply fungicides for soybean rust control, don't forget to look for insect resurgence later in the season. (See: Implications of soybean rust control measures on insect populations KPN #1045 Jan 2005) http://www.uky.edu/Agriculture/kpn/kpn_05/pn050124.htm#soyimp
Change in Threshold for 2005. Research results from the 2004 season have caused us to change our threshold statements for 2005. The threshold number of aphids per plant remains at 250. However, the time (growth stage) when this number should be used to make a decision has been altered. In 2005 if you have 250 aphids per plant (on average for a 30 plant sample per field) any time during the vegetative (V) stages, through reproductive stage 5 (R5-beginning seed), then an insecticide application is appropriate. At R6 ( full seed) a return might be possible but is much less likely. After the R6 stage, applications will not be economically appropriate. If on line, click HERE to see pictures of soybean plant stages. NOTE: the aphid thresholds with these photos are from 2004! Also, to avoid having to use 30 plants per field, check out the Speed Sampling Scheme below.
New Speed Sampling scheme. The University of Minnesota, Department of Entomology, has developed a method of Speed Scouting. This method allows the use of as few as eleven samples and no more than the standard thirty plant samples to make application decisions. Information and LINKS will be in the next issue of KPN.
Likely Situation in Kentucky in 2005.
Trying to keep up with the rapidly changing soybean rust situation has been, and will continue to be, a major challenge for everyone caught up in the soybean rust saga. To help with this, the University of Kentucky, College of Agriculture has created a free List-Serve which is open to anyone interested in soybean rust. Farmers, agrichemical dealers, consultants, Extension faculty, news media, government employees, commodity leaders, and the general public are all invited to subscribe to the University of Kentucky Soybean Rust List-Serve. By signing up, you will receive notification, by e-mail, each time the University's Soybean Rust website is updated. This web site is a gateway to extensive internet resources on soybean rust. It is also the best source for Kentucky-specific information on soybean rust. In addition, list members will receive periodic expert commentary, disease alerts, newsletter articles, publications, PowerPoint presentations, and data on soybean rust as soon as they become available.
To sign up for this free service, go to http://www.ca.uky.edu/soybeanrust. Click on "E-mail updates" and follow the instructions.
For the foreseeable future, fungicides will be the main way that soybean rust is managed in the U.S. As a result, growers will be asking many questions over the next months and years that relate directly to fungicide use decisions and application. Questions such as:
The above questions are just some of the many different questions that are likely to be asked by soybean producers this summer.
One take-home message of this article is that there are a great many questions for which we simply do not yet have answers. As a result, there will be a steep learning curve for all of us as soybean producers take steps to manage soybean rust in 2005 and beyond. There is a great wealth of information available from Africa, Asia, and South America on how to manage soybean rust with fungicides. However, the U.S. is unique in many respects and it is not possible to know with any degree of certainty how the soybean rust drama will play out here. International experience and research data are being used to develop rust control strategies for U.S soybean, but most scientists would agree that the answers to many specific questions being asked will only become available as we develop our own research and experience base. Certainly, some mistakes will be made as we move into uncharted territory. Therefore, read international reports and study international data, but don't be lulled into thinking that everything that happens in Brazil, for example, is directly transferable to the U.S.; it is not.
Soybean producers are being bombarded with information, resources, and products from every direction. This trend will most definitely intensify as the season approaches. It seems like everyone (including us) has a fact sheet, a newsletter, a website, etc, that has been developed to keep soybean producers and others, as up-to-date as possible on the rapidly changing soybean rust situation. The fact is that there IS a great deal of very excellent information available through the internet or through other sources. There is also a significant body of marginally accurate, or even inaccurate, information. We must all become informed enough that we will be able to separate the "wheat from the chaff" when it comes to information sources. My suggestion is that you seek out and follow a few sources of information which are unbiased, stay current, are highly credible, and are diverse. These are not hard to find and include several government, university, commodity, and industry web sites and resources. You will need to discern for yourself which ones to latch onto, based on your specific needs. If you add these to your "favorites" list, it will be hard to go too far astray.
Finally, there is considerable confusion in the marketplace on how soybean rust fungicides compare with each other in terms of: when and to what degree they are active against soybean rust, efficacy at various use-rates, length of residual at different use-rates and disease pressures, potential for fungicide resistance, mixing partners, etc. I hear many different things myself and much of it is conflicting. My suggestion is that you take a balanced approach to learning about soybean rust fungicides. Read and listen to what the fungicide manufacturers have to say. Then compare that information with what university and government scientists, and even competing manufacturers, are saying. Certainly, the label is the final authority and must be followed. However, labels tend to have "grey areas" which are open to interpretation. Read, study, compare and formulate an opinion; there really is no alternative to becoming better informed. Make a list of questions and areas of concern and take them to your chemical salesperson for clarification. They may not be able to answer all your questions, but they all have resource persons they can call on to answer technical questions. But, as I indicated above, understand that they, too, do not have all the answers.
For more information about soybean pests, visit
"Insect Management Recommendations".
A variety of holes and excavations, ranging from mole runs to insect and earthworm diggings can show up in turf at this time of year. The large fresh mounds and runs from mole activity are relatively distinct but there smaller holes can be from a variety of different creatures.
Here are some signs that may be seen over the next few weeks:
1) Holes caused by green June beetle grubs are about the diameter of an index finger and may be surrounded by small mounds of loose soil and fecal pellets. These grubs work extensively in soils with high organic matter content. Usually, they remain deep in response to cold temperatures but they can stay active and visit the surface at this time of the year during mild winters. Unlike other white grubs, they come to the surface at night and may crawl long distances (10 ft or more) on their back. Green June beetle grubs do not feed much on grass roots so their impact is primarily limited to areas immediately around tunnel openings. In extreme cases, grass can be killed, opening up places for weed germination.
2) Earthworm castings are similar in appearance to those left around a tunnel entrance by green June beetles. Brush away the castings and the tunnel entrance should be much smaller, about the diameter of a pencil. Earthworms are favored by food - organic matter, moisture, cool, light to medium-textured soils. They are less active in heavy clay or coarse sandy soils or acidic soils. Earthworm castings can be an annoyance but typically are a sign of a healthy soil.
3) Crayfish chimneys can appear where the water table is near the surface. The tunnels of these nocturnal arthropods can extend more than 3 ft below the surface. Crayfish activity is usually seasonal and will subside. There are no registered pesticide treatments due to the high potential for groundwater contamination. Over the long term, tiling or improvements in drainage may help to reduce crayfish activity but this often is impractical.
A few weeks ago, a report was made in this newsletter of the survey for Phytophthora ramorum in Kentucky nurseries. This second article describes an informal survey of parks and natural areas done in central and eastern Kentucky. This survey was funded in part by the Cooperative Agricultural Pest Survey (CAPS).
Introduction. During recent years, sudden oak death (SOD) caused by a fungus-like organism new to the U.S., Phytophthora ramorum, has appeared in the coastal regions of northern California and Oregon. The fungus causes bleeding necrosis on the trunks and limbs of affected oak and tanoak trees and can girdle and kill infected trees. The fungus also infects foliage, causing spots, blotches, or leaf tip necrosis of many kinds of plants without much notice or harm to the plants. These infected "carriers" of SOD may include rhododendrons, camellias, bay laurels, maples, viburnums, honeysuckles, buckeyes and many other trees and shrubs.
In Kentucky, we are concerned about whether or not this disease would be similarly devastating to oaks if the pathogen were introduced into the state. The SOD disease organism thrives in the relatively cool and moist climate of coastal California and Oregon. Since we also can have periods of cool, moist weather in spring and sometimes in fall, the disease might thrive here, too. The wide host range of the fungus in nature and in greenhouse inoculations includes Kentucky native woody plants such as red oaks, rhododendrons, viburnums, and mountain laurels.
P. ramorum is known to be capable of being moved in soil, such as that stuck to hiking boots and to automobile tires. On the chance that P. ramorum has already been introduced into the state, selected Kentucky state and national parks and natural areas were surveyed in 2004 for the presence of P. ramorum.
Parks and natural areas survey. The parks and natural areas survey was done mainly during September and October when relatively cool temperatures would favor P. ramorum diseases. Collections were made from plants growing mainly along well-traveled trails. Trail-side vegetation was examined for plants showing abnormal symptoms including bleeding necrosis, leaf spots, blotches and leaf tip necrosis. Species such as oaks, rhododendrons, viburnums, and mountain laurels were especially scrutinized.
Plant specimens were collected, labeled, placed in plastic bags, double-bagged and immediately taken to the laboratory for analysis. Small pieces of infected plant material were tested for the presence of Phytophthora using an enzyme-linked immunosorbant assay (ELISA) test. Samples were also plated on a culture medium selective for Phytophthora (PARP) and were floated on water in Petri dishes. Samples testing positive with the ELISA test were further tested for Phytophthora fungi closely related to P. ramorum with a polymerase chain reaction (PCR) test. ELISA- and PCR-positive samples were considered presumed positives and were sent to the USDA-APHIS lab in Beltsville, Maryland for confirmation.
Survey results. Park and natural area collections were made at the following 11 locations: Bernheim Forest (Bullitt Co.), Big Bone Lick State Park (Boone Co.), Carter Caves State Park (Carter Co), Cumberland Falls State Park (Whitley Co.), Kentucky Horse Park Fayette Co.), Mammoth Cave National Park (Edmonson Co.), Natural Bridge State Park (Powell Co.), Pine Mountain Settlement School (Bell Co.), Shaker Village of Pleasant Hill (Mercer Co.), Tygart State Forest (Carter Co.), and University of Kentucky (Fayette Co.). These locations are mainly in central and eastern Kentucky and from these locations, collections were made from 51 indigenous plants showing disease symptoms.
In this survey, the following specimens were collected and tested: nine rhododendrons; eight red oaks; five pin oaks; four European beech; three shingle oaks; two each of American beech, azalea, elm, lilac, magnolia, and mountain laurel; and one each of bottlebrush buckeye, chestnut, chestnut oak, chinquapin oak, filbert, hickory, maple, redbud, viburnum, and witch hazel. Of the 51 plant samples taken, three rhododendrons tested positive using the ELISA test and one of those tested positive with PCR. DNA from the ELISA and PCR "suspect positive" was sent for confirmation by the USDA-APHIS laboratories. This sample then tested negative for the disease. No isolates of P. ramorum were cultured. This survey suggests that for now, P. ramorum infected plants are absent from or are not easily found associated with the Kentucky parks and natural areas surveyed.
Conclusion. We in Kentucky are thus far fortunate that P. ramorum is apparently not yet here in Kentucky. This disease of West Coast nurseries could
greatly impact the forest industry in Kentucky with broad implications for the Kentucky nursery industry. Forest and nursery surveys are expected to continue in 2005.
Small vials containing gnats have been appearing in the Insect ID lab mailbox. They have been fungus gnats, generally associated with very moist plant media or wet soils. Usually, the white to cream, darkheaded larvae are in the potting soil or media where they feed on organic matter. However, these legless larvae also can feed on plant roots. The adults can be found most anywhere in the house but frequently accumulate at windows or around lights.
If over-watered house plants seem to be a reasonable source, then allowing the media to dry more between waterings can reduce the problem. In some cases, no obvious source can be located. Fortunately, the gnats are short-lived and disappear on their own.
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