As the cotton harvest continues, it is important 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 (BWEP). This year there has been a 90% reduction in the number of boll weevils caught in the local area as compared to last year. Good progress has been made on this front, so lets keep the weevils on the march and out of town for good!
The Chairman of the Zone 2 Cotton Producer Advisory Committee has sent a request to TDA to extend the cotton stalk destruction deadline for Zone 2, Areas 1, 2 & 3. Citing weather conditions that delayed cotton planting at the beginning of the season, along with seasonal weather that delayed crop maturation, the committee chairman is requesting the deadline for these areas with a September 1st and September 15th deadline be extended to September 22, 2010. This change in deadline will be in effect for the 2010 crop year only.
Counties affected by the extension include: Jim Wells, Kleberg, Nueces, San Patricio, Duval, Webb and the southern portions of Bee, Live Oak and Aransas counties.
In its native habitat cotton is a perennial shrub that may survive for many years. The perennial habit of cotton allows it to regrow 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 in three to four weeks.
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 which 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 (eg. 1 qt. of a 4 lbs. a.i./gal. formulation). Generally, a second application of 0.5 to 1.0 lb. a.i./acre will be necessary for control of any live stalks and emerged cotton seedlings.
To obtain optimum results, cotton stalks should be shredded (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/acre. Also, the addition of surfactant at the rate of 0.5% v/v (2 qts./100 gals. water) is recommended. In a recnet study conducted at the Texas AgriLife Research and Extension Center, there was essentially no difference in killing regrowing cotton plants with 2,4-D between treating shredded or left standing stalks,
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!
