UGA Cotton Newsletter

October 20, 1999

Cotton Situation. (Brown) The old saying, "a bad crop gets worse," accurately represents where we are in 1999. USDA lowered its estimate for Georgia to an average yield of 530 lb/A with total production at 1.6 million bales. That average may fall to around 500 lb/A as harvest progresses. As much as 60,000 to 70,000 acres are being mowed down in east and central Georgia due to extremely low yields.

Quality, particularly in terms of staple length, has also been a serious problem across the eastern half of the Cotton Belt. Fiber length less than 34 (measured in 32nds of an inch) is discounted. Fiber elongation occurs during the first 16 to 25 days after bloom, and environmental stresses in that period can adversely affect length. Such stresses include water, heat, and potassium deficiency. A likely cause of widespread problems with short fiber are the joint effects of high night temperatures and high relative humidity.

There are reports from several areas in the state of extremely poor boll retention (less than 5 bolls per plant from 15+ fruiting branches). In many instances, this has included well managed, irrigated cotton. While some of these fields set a few bolls late in the season, others did not. No doubt, yields will be disappointing.

Efforts to determine the cause are on-going. Plant map data have been collected from several hundred fields and from variety trials across the Southeast. Early summaries show a wide range of fruit retention across all varieties (transgenic and otherwise), and thus we are a long way from knowing the related environmental and management factors involved.

Weed Management for 2000 Season Begins Now. (Culpepper) The first step in a successful weed management program is to identify the problem. This is best accomplished by weed mapping. Survey fields now and record on a field map the weed species and their general population levels. Species present in the field now will be the predominant problems next season.

You can better plan a herbicide program if you know ahead of time what weed species to expect. Additionally, by referring to weed maps over a period of years, you can detect shifts in weed populations and make adjustments in your herbicide program to deal with these weed shifts as they occur.

Sample for Nematodes Now for Best Results. (Davis) The most important step in nematode management is to identify which nematode species are likely to cause damage in a given field. All nematode management decisions depend on that first step, so population assessment cannot be over-emphasized. In cotton, as in most row crops, this first step is accomplished primarily through soil sampling, and NOW is the time to sample to get the most meaningful results.

Population levels of all plant-parasitic nematodes are influenced by two factors that change significantly this time of year: food availability and soil temperature. Diminishing plant food resources and temperatures decline in the fall and result in a decline in nematode populations. Therefore, sampling for nematodes should be performed NOW. Assessments much later in the year will provide unreliable counts and may confuse management decisions.

When cotton plants are defoliated, the amount of food they produce for nematodes is drastically reduced. Nematode population levels may remain steady for a short time, but soon decline. This is especially true for root-knot nematodes. While nematode eggs are highly durable and will survive until the following spring, worm-like stages decline as the fall progresses. As a result, counts late in the year often underestimate populations of the worm-like stages and thus may fail to identify potential problem fields. Sampling prior to or just after defoliation is ideal. The next best choice is immediately after harvest and stalk destruction. Mowing makes sampling and other field activities much easier.

The effect of declining soil temperature is less dramatic than the effect of defoliation because it happens over a longer period of time. Nematode metabolism, like that of insects, is dependent on external temperatures. As soil temperature declines, all nematode activity eventually stops. When eggs stop hatching and already-hatched nematodes die or enter roots for protection, the population extracted from soil samples declines. When apparent population levels decline below threshold levels, potential problems cannot be identified from soil samples. In other words, delayed sampling often grossly underestimates nematode numbers and fails to trigger appropriate management options.

Crop Management Seminar, November 3^rd and 4^th, Augusta, Georgia. (Roberts) Cotton Incorporated is sponsoring a Crop Management Seminar on November 3^rd and 4^th in Augusta, Georgia. The topic for the seminar is "Cotton Production in the Southeast: New Technology for a New Millennium." The seminar will provide an opportunity for participants to discuss events of the growing season, exchange ideas, share information, and learn about new technologies on the horizon. The seminar will be held at the Radisson Riverfront Hotel in Augusta. Cotton Incorporated will provide complimentary meals on Wednesday evening and during the seminar on Thursday. A tentative outline for the seminar, hotel information, as well as additional information about the seminar can be found on the Cotton Incorporated Website:

http://www.cottoninc.com then Crop Management Seminar

Registration is required. Size of the conference space may limit the number of registrations that can be accepted.

If you have additional questions or need more information, please let me know. (Phone 912/386-3424 or email proberts@arches.uga.edu)

Calendar

November 3-4, 1999 - Cotton Incorporated Crop Management Seminar, Augusta (see attached announcement)
December 8-9, 1999 - Georgia Crop Production Alliance Annual Meeting, Macon
December 15-16, 1999 - Georgia Cotton Production Workshop, Tifton
January 4-8, 2000 - Beltwide Cotton Conference, San Antonio, TX

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