Time to terminate irrigation on 2007 Oklahoma cotton

No more water is the unfamiliar advice being given by Dr. J. C. Banks, Oklahoma State University Agricultural Extension state cotton specialist at Altus.

"It is quickly approaching the time producers need to consider terminating irrigation on cotton," Banks says. "Factors involved in this decision are stage of the crop and the amount of water available in the soil profile.

"Generally, our rule of thumb in the irrigation district is to have a full soil water profile near the first of September. This will allow the young developing bolls to finish fiber development without encouraging late vegetative growth. In a normal year, we have about a 50 percent chance of maturing blooms that are on the plant Sept. 1. If the plant has a heavy boll load, that percentage decreases due to the stress the developing bolls have on the plant and the resulting shed of small bolls.

"On furrow irrigation, the full profile of water Sept. 1 remains the best decision, but on circle irrigated or drip irrigated fields, the final irrigation date will probably need to be extended by approximately one week. Overhead irrigation normally is not heavy enough at each application to fill the soil profile. Drip irrigation has the plant trained to get water from the emitters. On termination of irrigation at these areas, the plant will stress for water much more quickly than when the profile is full."

Cotton crop conditions vary widely across the U.S. cotton growing area, according to the weekly USDA report.

A slight decline in the overall crop condition is seen with the Southwest generally receiving adequate to excessive rainfall in some cases. Overall, the crops in Kansas, Oklahoma and Texas are rated as average to above-average. The percentages of the crop in the Good to Excellent categories are: Oklahoma, 66 and six percent; Texas, 37 and 14 percent; and Kansas, 45 and 10 percent.

As of Aug. 26, 12 percent of the national crop is rated Excellent and 37 percent Good. At the other extreme, six and 14 percent of the crop are rated Very Poor and Poor, respectively.

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