Cooler temperatures and low humidity brought by the passing front of Sept. 10 should help mitigate cotton conditions in the Delta region. Weather has not only affected cotton lint and seeds but has stimulated tremendous re-growth in all fields.
Most cotton defoliated before the rains will most likely need some type of treatment before picking. Considering the necessity of having the seed-cotton as dry as possible before moduling and ginning. A desiccant may be necessary in some fields. An application of one of the phosphate materials (Def/Folex) plus paraquat (Gramoxone Max/Boa etc.) or sodium chlorate plus paraquat (Gramoxone Max/Boa, etc.) are examples of good second treatments for this situation.
For first applications, hormone type defoliants will generally do a better job removing the young tender regrowth and inhibiting of regrowth. A tank mix of Dropp/FreeFall plus ethephon (Prep, Super Boll etc.) or Dropp/FreeFall plus Finish or Cotton Quick are excellent choices for removing young juvenile plant material and for regrowth suppression.
In some situations, a three-way combination of Dropp/FreeFall plus Harvade plus ethephon (Prep/Super Boll etc.) or Leafless (a prepack of Dropp plus Harvade) plus ethephon may be a consideration. In most all cases, these primary treatments will need to be followed by applications as stated above. Rates of selected materials should be based on field and weather conditions. The materials and combinations listed are only examples and there are numerous materials and/or combinations that will perform adequately in various respective situations.
Where weeds top cotton, it is suggested that the cotton be defoliated first with materials that will retard re-growth and the weeds be attacked in a follow-up application. Combinations of defoliants and desiccants in an initial or primary application may lead to excessive leaf sticking and reduce already deteriorated grades.
The following recommendations should be strongly considered for the 2001 harvest season for cotton defoliated prior to rains where open cotton bolls have been exposed to excessive moisture.
- Cotton should only be harvested after at least five to seven additional days of sun exposure than normally used to allow the germinated cottonseed to die and dry out some as well as allow the other cottonseed to dry. These five days should have low to moderate relative humidity, moderate to high heat, and high sunlight. In most instances, if at least 50 percent of the cottonseed is firm, the cotton can be ginned. The sunshine will possibly move the color of the cotton from light spot or spotted to white.
- If harvested too quickly, seed cotton moisture will be excessive and the seed cotton cannot be stored either in trailers or modules for more than 24 hours. Again, this cotton cannot be stored more than 24 hours either in modules or trailers if the moisture is excessive. Module temperatures must be monitored in at least six locations immediately after module formation and every 12 hours afterward for at least 6 days. If temperatures rise more than 20 degrees or reach 120 degrees, gin immediately.
- At the gin, substantial drying will be required to ensure that the gin stand remains operational. Substantial seed coats will be in the lint after the gin stand due to the germinated cottonseed, and two stages of lint cleaning will likely be required. If air-type lint cleaners are used, care must be exercised to ensure that substantial quantities of fiber which is attached to the seed coat is not removed; it may be necessary to close the opening in the air jet cleaner to reduce or prevent excessive fiber loss.
- The cottonseed will be of limited value due to quality degradation. Initial results indicate that less than 50 percent of the cottonseed are marketable, and they will be graded 75 or below and discounted for excessive moisture. Cottonseed value may be less than 30 percent of normal.
- Fiber quality will be near normal except for the degradation caused by extra drying needed at the gin, additional light spots and seed coat fragments.
- The potential for high-moisture lint after ginning necessitates careful use of moisture restoration systems.
Note: Relatively impermeable polyethylene bagging for bale covers may be a potential problem since excess moisture may be in the cotton.
Will McCarty, Mississippi State University, Charles E. Snipes, Delta Research and Experiment Center, and W. Stanley Anthony, Supervisory Agricultural Engineer/Research Leader, U.S. Cotton Ginning Laboratory, wrote this article.