UGA COTTON NEWSLETTER - APRIL 26

April 26, 2000 http://www.griffin.peachnet.edu/caes/cotton

Crop Situation 1
Cotton Seedling Diseases 1
Thrips Management 2
Whiteflies 2
Scout Schools 2
Milan No-Till Field Day 3
Glyphosate Update for 2000 3

Crop Situation. (Brown) Over the past 4 weeks, soil moisture has declined considerably. Planting began in earnest the week of April17, and as of April 24, about 10 percent of the expected 1.5 million acre Georgia crop is planted. Both dry and cool conditions have restrained planting. Rains on Monday improved the overall situation in extreme south Georgia.

The scramble for seed continues. Shortages in transgenic options are due primarily to two factors: (1) under estimation of grower interest in Roundup Ready technology (and the lack of commitment to RR variety seed production) and (2) cool test problems with numerous seed lots of DP 458 B/RR, a variety which had been expected to occupy over 3 million acres across the Belt. Growers are looking to fill their needs with "new" varieties with similar technology. Unfortunately, many of these varieties have had limited exposure in the state, and that puts us in the same position we have regrettably found ourselves in the past couple of seasons.

Cotton Seedling Diseases. (Kemerait) Seedling diseases caused by Rhizoctonia solani and Pythium spp. are sporadic, yet important problems for cotton growers in Georgia. Severe seedling disease often results in a poor stand and reduced yields at harvest. Growers can minimize the impact of seedling disease by using high quality, healthy seed; planting when soil temperatures are warm enough to promote rapid, vigorous germination; and using fungicide seed treatments. Crop rotation can also be an effective way to reduce populations of these pathogens; however, suitable rotation crops are usually not economically feasible for the grower.

Applications of in furrow fungicides are also an effective means of protecting the germinating seeds and young seedlings, but require added expense for the grower and possible modifications to planting equipment. In furrow fungicides are most warranted in fields with a history of seedling diseases and when early planting dates and cool soil temperatures increase the risk of disease. A study being conducted at the Coastal Plain Experiment Station in Tifton this season is being used to compare the efficacy of fungicides that should be labeled for cotton in the near future against more traditional fungicides that are currently used by growers in Georgia.

While the importance of seedling diseases in cotton is recognized in Georgia, it is difficult to determine just how widespread this problem actually is. I would appreciate hearing from county agents when they observe fields in their county that have a high incidence of seedling disease. Such observations could then be documented and used in developing management strategies in the future. I can be reached at (912) 386-7495 or by e-mail at Kemerait@arches.gnv.uga.

Thrips Management. (Roberts) Failure to control damaging populations of thrips will result in stunted plants, delayed maturity, and in severe cases, stand loss. Thrips damage young seedlings by rasping tender plant tissues and feeding on escaping plant juices. Unfurled leaves which are damaged by thrips feeding in the terminal bud will have a crinkled appearance upon expansion. Since thrips are an annual pest of cotton in Georgia, a preventive treatment is recommended at planting. Several options for delivery of systemic insecticides for thrips control exist and include in-furrow granules, in-furrow sprays, or seed treatments. The majority of cotton in Georgia is treated with insecticide granules applied in-furrow.

It is important that all granule applicators on a planter are correctly calibrated. It is not uncommon for there to be row-to-row variation during calibration. If variation exists, applicators should be thoroughly cleaned and correctly calibrated. Failure to calibrate correctly could result in excess insecticide being applied, resulting in unnecessary cost, or conversely, too little insecticide being applied, resulting in inadequate control.

The most severe damage appears when immature wingless thrips are present in seedlings. The presence of immatures suggests the insecticide is not present at a sufficient concentration in the plant to provide control. Environmental factors such as drought or excessive moisture can influence efficacy of preventive treatments. All fields should be scouted for thrips from emergence until the five leaf stage. Damage is unlikely if seedlings are growing vigorously and have reached the five leaf stage. Foliar treatments are recommended if thrips number 2 to 3 per plant,, especially if immature thrips are observed. The use of a hand lens can aid in determining the presence (adults) or absence (immatures) of wings.

Whiteflies. (Roberts) Silverleaf whitefly was a serious problem of cotton in parts of the state last season. The most intense populations occurred in the southern part of Tift County and surrounding areas. We have received a few calls concerning the presence of whiteflies in landscapes during recent weeks. Callers are asking if the silverleaf whitefly that was so abundant last fall in south Georgia has come out early this year. This is not the case. The whitefly is being observed in high numbers at this time is the citrus whitefly which is much larger than the silverleaf whitefly. Citrus whitefly has a restricted host range and feeds and reproduces on citrus, gardenia, privet, chinaberry, and sometimes viburnum. There are only two generations per year, with adults emerging in April and again in August. Adults are active for 2 to 3 weeks, and then they disappear until the next generation matures in late summer. Huge numbers develop on privet and chinaberry in the summer, but most of the flying adults this time of year come from privet (various Ligustrum species). To date we have not had warm temperatures which would allow the buildup of silverleaf whitefly. At this point in time we cannot predict what type of silverleaf whitefly populations will be encountered in late summer.

Scout Schools. (Roberts) Several cotton scouting schools have been scheduled for the upcoming weeks. The annual Cotton Scouting Schools held at the RDC in Tifton will be held on Saturday June 3 and Monday June 12. Registration is required for the training sessions held at the RDC. Several additional scout schools are being conducted in various counties. Contact the respective county extension office for more details about these schools.

Date Location Date Location
29-Apr Decatur, Seminole 3-Jun RDC
6-May Worth June 6-7 Jeff Davis
6-May Crisp, Dooly, Wilcox June 8-9 Evans
13-May Brooks 12-Jun RDC
13-May Bleckley, Dodge, Pulaski June 15-16 Burke

Milan No-Till Field Day. (Brown) The Milan No-Till Field Day in Milan, Tennessee, is one of the best field days in all the South. It showcases the latest in conservation tillage equipment and technology. We have put together a tour/trip for the 2000 field day, which is on July 27. Attached is the schedule and registration form. Because of the limits of transportation (bus) and accommodations, participation is planned for 55, so you need to reserve a spot soon. The tour is open to growers, county agents, industry personnel, and anyone with an interest in agriculture.

Glyphosate Update for 2000. (Culpepper) The availability of products containing glyphosate (the active ingredient in Roundup and other products) has grown rapidly. With such an increase in accessibility, growers have benefitted from a reduction in the cost of these glyphosate products over the past several years. It has become confusing when determining formulations of each glyphosate product, assessing which of them can be applied in Roundup Ready cotton, and specifying the need for additional adjuvants.

The tables on pages 4 and 5 list some of the glyphosate products available, adjuvant suggestions, and whether or not they are labeled for use in the 2000 Roundup Ready cotton crop. Since there may be other glyphosate-containing products that are not listed in the tables below and because all of the products have not been compared with one another for weed control or crop tolerance, always read and follow label recommendations.

Special thanks to Dr. Alan York of NC State University for help in preparation of this section.

Prepared by:

Steven M. Brown, Extension Agronomist-Cotton
A. Stanley Culpepper, Extension Agronomist-Weed Science
Bob Kemerait, Extension Plant Pathologist-Cotton

Glyphosate Products
Brand Name Company Formulation Contents Adjuvant Recommendations Use of Glyphosate Products on RR Cotton
Acquire BASF Liquid (S) 4.0 lb/gal isopropylamine salt of glyphosate 2 qt nonionic surfactant per 100 gal may be added; 8.5 to 17 lb AMS per 100 gal may be added. No
Credit Nufarm Liquid (S) 4.0 lb/gal isopropylamine salt of glyphosate 2 qt nonionic surfactant per 100 gal may be added; 8.5 to 17 lb AMS per 100 gal may be added. No
Glyfos Cheminova Liquid (S) 4.0 lb/gal isopropylamine salt of glyphosate 2 qt nonionic surfactant per 100 gal may be added; 8.5 to 17 lb AMS per 100 gal may be added. No
Glyfos X-TRA Cheminova Liquid (S) 4.0 lb/gal isopropylamine salt of glyphosate AMS at 8.5 to 17 lb per 100 gal may be added. The equivalent rate of AMS in liquid formulation may be used. Yes
Glyphomax Dow Liquid (S) 4.0 lb/gal isopropylamine salt of glyphosate 2 qt nonionic surfactant per 100 gal may be added; 8.5 to 17 lb AMS per 100 gal may be added. No
Glyphomax Plus Dow Liquid (S) 4.0 lb/gal isopropylamine salt of glyphosate AMS at 8.5 to 17 lb per 100 gal may be added. The equivalent rate of AMS in liquid formulation may be used. No
Glyphosate Original Griffin LLC Liquid (S) 4.0 lb/gal isopropylamine salt of glyphosate 2 qt nonionic surfactant per 100 gal may be added; 8.5 to 17 lb AMS per 100 gal may be added. Yes
Rattler Helena Liquid (S) 4.0 lb/gal isopropylamine salt of glyphosate 2 qt nonionic surfactant per 100 gal may be added; 8.5 to 17 lb AMS per 100 gal may be added. No
Roundup D-Pak Monsanto Liquid (S) 6.42 lb/gal isopropylamine salt of glyphosate 2 or more qt nonionic surfactant per 100 gal; 8.5 to 17 lb of dry AMS per 100 gal may also be added, or equivalent rate of AMS in liquid formulation may be used No
Roundup Original Monsanto Liquid (S) 4.0 lb/gal isopropylamine salt of glyphosate 2 qt nonionic surfactant per 100 gal may be used; 8.5 to 17 lb of dry AMS per 100 gal may be added. No
Roundup Ultra Monsanto Liquid (S) 4.0 lb/gal isopropylamine salt of glyphosate AMS at 8.5 to 17 lb per 100 gal may be added. The equivalent rate of AMS in liquid formulation may be used. Yes
Roundup UltraDry Monsanto Dry flowable (DF) 71.4% ammonium salt of glyphosate AMS at 8.5 to 17 lb per 100 gal may be added. The equivalent rate of AMS in liquid formulation may be used. No
Roundup UltraMax Monsanto Liquid (S) 5.0 lb/gal isopropylamine salt of glyphosate AMS at 8.5 to 17 lb per 100 gal may be added. The equivalent rate of AMS in liquid formulation may be used. Yes
Staple Plus Dupont Co-pack

4.0 lb/gal isopropylamine salt of glyphosate

and

85% pyrithiobac sodium (Staple)

 Follow label directions; finalized label unavailable as of April 20, 2000.

Yes
Touchdown Zeneca Liquid (S) 5.0 lb/gal trimethylsulfonium salt of glyphosate (also called sulfosate) 1 qt nonionic surfactant per 100 gal may be added; AMS at 8.5 to 17 lb/100 gal may be added. The equivalent rate of AMS in liquid formulation may be used. No**
**Research has shown unacceptable injury to Roundup Ready Cotton.

20th ANNUAL MILAN NO-TILL FIELD DAY TOUR

JULY 26-28, 2000

MILAN, TENNESSEE

The University of Georgia Cotton Team with the assistance of the Tifton Campus Conference Office are coordinating a three day, two night trip to the University of Tennessee Milan Experiment Station's No-Till Field Day to view the latest equipment and technology pertaining to no-till crop production.

Tour package includes: