As the cotton harvest continues, it is important for cotton growers not to forget about destroying those cotton stalks as soon as the crop has been removed from the field to aid in reducing costs for the Boll Weevil Eradication Program.
This year there will not be an early stalk destruction rebate program from BWEP in order to help retire debt for the BWEP, which will ultimately reduce the program costs for cotton growers. The local stalk destruction deadline remains Sept. 1 for Zone I and Zone II, areas 1, 2 &3.
In its native habitat, cotton is a perennial shrub that may survive for many years. The perennial habit of cotton allows it to re-grow following harvest, providing the potential for development of hostable fruit (squares and bolls) for boll weevil feeding and reproduction.
Under good environmental conditions, cotton plants can generate hostable fruit within three to four weeks following harvest.
When field conditions and weather are favorable for tillage, stalks can be shredded and then disked to destroy the intact plant. Stubble stalk pullers can also be used to uproot the stalk.
These mechanical methods are generally successful, but some stalks may survive these operations. Also, many growers are implementing reduced tillage systems that do not allow for primary tillage operations, causing producers to evaluate new methods for stalk destruction.
There has been much interest in alternative cotton stalk destruction throughout the South Texas area in recent years. While many producers still use various tillage methods to destroy their cotton stubble, be aware that there are other choices available.
Regardless of the method chosen, the primary purpose of destroying cotton stalks remains the same and that is the removal of both feeding and fruiting sites that may be used by the boll weevil to reproduce.
Several herbicides have been registered for cotton stalk destruction. Herbicides available include, but are not limited to 2,4-D (ester and salt formulations), several dicamba products (Weedmaster, Clarity, Banvel), and Harmony Extra (thifensulfuron-methyl + tribenuron-methyl).
For these products to be legal for cotton stalk destruction, the label must contain a section addressing "crop stubble" or specify cotton as the target pest following harvest.
Based on most recent field research, it appears the low-volatile, amine salt formulations are equally as effective as the ester formulations for cotton stalk destruction, and minimize problems associated with off-target drift.
The first application should be at the rate of one pound of active ingredient/acre. Generally, a second application will be necessary for control of any live stalks and emerged cotton seedlings.
To obtain optimum results, cotton stalks should be shredded to a 6- to 8-inch height and the spray application should be made soon after shredding. Best results are achieved if the herbicide is applied the same day as the shredding operation. To achieve optimum effectiveness, some growers have mounted spray booms directly on their flail shredders and are banding their herbicide during the shredding operation, and achieving excellent results.
Note that thorough coverage is essential, and should be in the range of 5 to 10 gallons water per acre. Also, the addition of surfactant is recommended.
In a study conducted last year at the Texas AgriLife Research and Extension Center, there was essentially no difference in killing re-growing cotton plants with 2,4-D treatments in shredded stalk stubble or stalks left standing.
If one uses a hormone herbicide like 2,4-D, remember that there is always that potential for off-target drift that might affect other susceptible crops in the area, so be careful and monitor local environmental conditions that could promote the off-target movement of the product.
As we work to wrap up another cotton harvest, it is important to remember that without an effective cotton stalk destruction program here in South Texas, boll weevil eradication cannot be accomplished.
Jeffrey Stapper is the Agricultural and Natural Resources Agent for Nueces County. Readers may contact him at (361) 767-5217.