Agricultural Extension Service

The University of Tennessee

IPM NEWSLETTER

For Pest of Field Crops

edited by

Scott D. Stewart, Cotton IPM Specialist

No. 1 June 7, 2002

NOTE: This newsletter will be distributed weekly throughout the growing season. If you do not want to receive an electronic copy of this newsletter in the future, let us know by e-mail reply. Please make us aware of anyone who would like to be added to the mailing list.

New Extension Specialists at the West Tennessee Experiment Station

Scott Stewart B Cotton IPM Specialist

Scott is the Cotton Insect Pest Management Specialist for the University of Tennessee. Scott comes to Tennessee via Mississippi State University where he had research and extension programs relating to IPM, primarily with cotton. His Ph.D. is from Auburn University, dealing with tarnished plant bugs. Scott received his degree from Texas A&M University, also working with cotton entomology. In all, Scott has about 20 years of insect pest management experience with cotton and other row crops.

Chism Craig B Cotton and Small Grains Specialist

Chism is the new Extension Cotton and Small Grains Specialist for the University of Tennessee. Chism comes to Tennessee from Louisiana where he recently completed his PhD at Louisiana State University. Chism=s Ph.D. research focused on cotton fertility, more specifically, cotton grown in rotation with corn and foliar applications of nitrogen on cotton. Chism received both his masters and undergraduate degrees from Mississippi State University. His masters degree is in Entomology where he evaluated non-crop hosts of tarnished plant bug and their movement into cotton. His undergraduate degree was in Agricultural Pest Management that focused on Entomology, Plant Pathology and Weed Science. He is a native of Friars Point, MS and grew up on a cotton and soybean farm.

Angela Thompson B Corn and Soybean Specialist

Angela received her Ph.D. in Weed Management from the University of Tennessee and her masters degree for the University of Kentucky working with johnsongrass control in field corn. She has had several years of work experience in agronomy including contract research in corn, soybeans, other field crops, and crop protection product development with DuPont Ag Products. Angela most recently taught agronomy courses at Southeast Missouri State University and conducted research in corn, soybeans, and rice.

Cotton Update

Current Crop Situation

by Chism Craig, Assistant Professor

According to the latest bulletin published by the Tennessee agricultural statistics service, 91% of the state=s cotton had been planted as of June 2^nd contrary to 100% last season and the 5-year average of 99%. This estimate does not take into consideration cotton that has been replanted. Recent dry weather and favorable planting conditions have encouraged planting and by now I feel that most cotton has been planted, at least for the first time.

Over the past several weeks I've had numerous calls about the adverse effects of cold weather, excessive moisture, seedling disease and insect injury. I've looked at several fields and some have needed replanting but other fields have had situations that made replanting decisions difficult. In most cases where the fields contained 1-2 plants per row foot and were uniformly spaced across the field, replanting was not recommended. In most years, thicker stands of late replanted cotton do not yield as well as the original, thin stand. I=m not saying that this is always the case but it happens more often than not. However, the window of opportunity for planting cotton has ended and we need to turn our planting attention to other crops. I realize that every situation is different and some growers must plant cotton but in most cases cotton planting should not be considered in June. Although, Tennessee has been spoiled in recent years with longer than normal growing seasons and higher than average DD-60 accumulation, long-term historical data tells us that in 50% of the last 30 years, the last effective bloom date for Jackson and Covington is August 8^th. This information utilizes temperature data from these locations along with the assumption that a minimum of 850 DD-60=s is needed to reach boll maturity, 14 days from defoliation to harvest and a completion of harvest on November 1^st. The bottom line is that blooms set after the second week of August have less chance of contributing to overall yield and are usually expensive to mature.

Because of the wide variety of planting dates across the state and the potential for a late crop, good earliness management must be employed. Earliness is generally a product of variety, planting date, sound fertility practices, favorable early season temperatures, first fruiting node, fruit retention and environmental factors leading up to maturity. Unfortunately several of these are out of our hands but there are several things we can still do to achieve earliness. At this point our attention needs to be focused on setting and protecting the crop that we can harvest. Maintaining at least 80% square retention along with judicious use of plant growth regulators will give us an opportunity to make a decent crop. However, all of these management tools will only be as good as our environment prior to and during boll fill. Listed below is a table of general cotton development. Keep in mind that these are only averages and varieties and others factors may influence this schedule.

Cotton Growth and Development

Development Stage Days (avg.) DD-60=s(avg.)

Germination and Emergence 4-10 50-60

Emergence to 1^st Square 30-40 425-475

Square to 1^st Bloom 20-25 300-350

White Bloom to Open Boll 45-65 850-1100

Planting to 60% Open Boll 130-170 2150-2300

The cotton crop has made strides with recent sunshine and heat along with adequate moisture and the application window for glyphosate is rapidly approaching in some fields. Listed below are the recommendations for glyphosate application to glyphosate resistant cotton.

Overtop Applications - Apply overtop from cracking until the 4 true leaf (node) stage of development (until the fifth true leaf reaches the size of a quarter). Overtop applications after this stage may result in boll loss, delayed maturity and/or yield loss. Do not exceed 2 pt./A (3ae) or 1.6 pt./A (3.7ae) with any single overtop application. Two overtop applications, at least 10 days apart and with at least two additional nodes developed following the first application, may be made. Directed Applications - After the 4 true leaf stage, applications must be made with post-directed or hooded sprayers. Sprays must be directed to the base of the cotton plant. Take care to minimize contact of the spray with cotton leave by placing nozzles in a low position directing a horizontal spray pattern under the cotton leaves and by using low pressure (less than 30 psi). Leaf contact may result in boll loss, delayed maturity and/or yield loss. Two directed applications, at least 10 days apart and with at least two additional nodes developed following the first application, may be made. Do not exceed 2 pt./A (3ae) or 1.6 (3.7ae) per application. A total of 4 qt./A (3ae) or 3.2 qt./A (3.7ae) may be applied to cracking or layby.

DD-60 Accumulation (TASS and NWS data)

Location 4/15/02 - 5/28/02 5/15/02 - 5/28/02

Ames Plantation 438 168

Brownsville 449 181

Covington 405 169

Dyersburg 440 180

Jackson 427 173

Memphis 454 183

Milan 396 167

Thrips damage B photo by Craig Massey

Cotton Insect Update

by Scott Stewart, Associate Professor

You don=t have to be a genius to figure out that much of the cotton got off to a bad start because of cool weather and/or excessive rainfall. Not surprisingly, this generated a lot of problems with seedling diseases and thrips. Much cotton in the state could still be characterized as seedling plants, and thus, thrips and cutworms are potentially the most damaging pests likely to damage the crop.

It is apparent that both seed and in-furrow treatments of insecticide have often not been sufficient to deal with prolonged thrips pressure on slow growing plants. Keep in mind that the presence of adult thrips (identified by the presence of wings) may indicate migration into fields. Adults must feed to acquire a lethal dose of systemic insecticide. The presence of immature (larval) thrips is a better indication that seed and in-furrow treatments are failing. Immature thrips are usually pale white to yellowish in color and lack wings. There are several species of thrips that commonly occur on cotton. The most common species is usually the tobacco thrips. However, flower thrips, eastern flower thrips, and western flower thrips may also be present. All species can potentially damage seedling cotton in a similar manner. The western flower thrips is more difficult to control with insecticides. The following web site provides more information about the biology and damage caused by these small but important cotton pests:

http://web.utk.edu/~taescomm/wtes/thrips.htm.

It is unusual for cotton beyond the 3 true leaf stage to require treatment for thrips, particularly if growing conditions are favorable and plants are growing rapidly. On 1-3 leaf cotton or 4-5 leaf cotton that has a poorly developed root system, foliar applications for thrips may still be justified. Applications should be considered if plants have 1 or more thrips per plant. On cotton older than the 3 true leaf stage, slow plant growth and indications of thrips feeding damage in the terminal bud should also be present before treatments are made unless populations are very high.

A list of recommended insecticides for the control of thrips is shown in the table below. All of these products are systemic organophosphates. Some pyrethroid insecticides are labeled for thrips control but are generally not recommended because of they are typically more expensive and less consistent in performance. They are also avoided to prevent the development of pyrethroid resistance in populations of tarnished plant bug.

Recommended Foliar Insecticides Treatments for Thrips in Cotton

Insecticide	Lbs. of active ingredient per acre	Amount of formulated product per acre	Acres treated per gallon of product
acephate (Orthene 90S, Address 90S)	0.18	3.2 oz.	----
dicrotophos (Bidrin 8)	0.1 - 0.2	1.6 - 3.2 oz.	80 - 40
dimethoate 4	0.1 - 0.2	4.0 - 8.0 oz.	32 - 16
methamidophos (Monitor 4)	0.1 - 0.2	3.2 - 6.4 oz.	40 - 20

Stay Ahead of the Game

Considering the sluggish and generally late start of the cotton, it is even more important than usual to properly manage early-season insect pests. Do not let tarnished plant bugs, cotton fleahoppers, or other pests cause excessive square loss. Maintaining pre-bloom square retention above 80% will greatly reduce the risk that insects will further delay the crop. Next week=s newsletter will focus on plant bugs and their management.

Revisions in Cotton Insecticide Recommendations for 2002

It=s too late for a full-blown revision to UT=s Cotton Insect Control Guide, but it is not too late to make some changes. Despite what anyone tells you, always read and follow instructions on the label. The label is the law and includes important information including use rates, post application re-entry intervals, pre-harvest intervals restrictions, and other important information.

Cruiser 5FS (thiamethoxam): It=s mostly water under the bridge now, but Cruiser (the new name for Adage) is recommended as a cotton seed treatment for thrips. Cruiser is a neonicotinoid insecticide like Gaucho (imidacloprid), and thus, will not suppress nematodes. The label rate for Cruiser is 7.65 oz/100 pounds of seed. Most research indicates that Cruiser will as well Gaucho.

Centric 25WG (thiamethoxam): This formulation of thiamethoxam is for foliar applications targeting aphids, plant bugs, and whiteflies. Centric is not recommended for control of stink bugs, but some suppression could be expected when this product is applied for other pests. This is also true for other neonicotinoid insecticides such as Trimax and Intruder (see below).

Trimax 4F (imidacloprid): Trimax will be replacing Provado 1.6F, also imidacloprid, in cotton. Its recommended uses will be similar to those in effect for Provado. However, Trimax is more concentrated than Provado, so less formulated product is needed.

Intruder 70WP (acetamiprid): Formerly called Assail, Intruder should give rapid and good control cotton aphids. The labeled use rate of Intruder on aphids is 0.025-0.05 lb ai/a.

Steward 1.25SC (indoxycarb): Steward has a full label for control of lepidopteran larvae in cotton, including tobacco budworm, bollworm, armyworms, and loopers. The typical rate range is 0.09-0.11 lb ai/acre. The label also includes suppression of tarnished plant bug populations that may also be in the field at the time of application. Like Tracer (below), this product will be especially useful for insecticide resistant populations of tobacco budworm.

Tracer 4SC (spinosad) for loopers: Tracer is already in the Cotton Insect Control Guide for control of tobacco budworm and fall armyworm. It will now also be recommended for looper control in cotton at use rates of 0.067-0.089 lb ai/a.

Bidrin 8E (dicrotophos): Bidrin will now be recommended for control of stink bugs in cotton (0.4-0.5 lb ai/a). Extensive testing across the Cotton Belt indicates that this is one of the most reliable compounds for control of green, southern green, and brown stink bugs.

Karate Z, Decis, Scout, Fury, Capture, and Baythroid: Although not in the current control guide, labeled rates of these synthetic pyrethroids will typically give good control of green and southern green stink bugs. However, pyrethroid insecticides will not be as effective as Bidrin and other organophosphate insecticides if brown stink bugs are a common component of the stink bug complex present in the field. Labeled rates of the above pyrethroids will also control bollworm infestations when properly timed. Thus, when pyrethroid applications are needed for bollworm control, they will have the added benefit of controlling green and southern green stink bugs.

Cotton Seedling Disease

by Melvin A. Newman, Professor

This has been the worst planting season for cotton in the last 30 years. In general, 25-40 percent of the cotton acreage had to be replanted or was planted back to another crop like soybeans.

Low soil temperatures and heavy rains allowed Ryzoctonia and Pythium to rot roots and stems (sore shin) of seedling cotton. Some of the major factors that had an influence on the cotton crop this year were:

Producers planting in cold soil or after planting, soil temperatures dropped to below 68⁰F.

Many producers used seed treatments and hopper box treatments instead of full rates of recommended in-furrow fungicides.

Producers using seed with low seedling vigor and/or low cold test.

Most producers using a lower seedling rate to reduce seed cost.

Some producers using an in-furrow, systemic insecticide without an in-furrow fungicide.

Some producers planting too deep.

Sore shin has been very severe and is close to impossible to control because it occurs at the soil surface.

Area Cotton Report B including Haywood, Shelby, Hardeman, Fayette, Tipton, Madison, and parts of Crockett County

by Craig Massey, Area Specialist (Plant and Pest Management)

Crop Conditions: Cotton planting is 99% complete with 75% emergence reported on 6/3/02. Cotto