Talkin’ cotton

Oklahoma State University Extension cotton specialist J. C. Banks says cotton needs early attention.

“The cotton plant is known as a slow starter and hopefully, a strong finisher,” he says.

“Cotton is sensitive to all forms of stress while emerging and becoming established, so early management usually centers on reducing stress on the plant as much as possible. Cool soil temperatures, wind, blowing sand, heavy rainfall, thrips and weeds will contribute to early season stress.

“Once we get the plant into squaring, it can handle more stress, but the result of too much stress is fruit shed.”

Banks says some cotton is beginning to respond to heat. “Cotton, being a tropical plant, is beginning to grow out of the early season stress. Usually, at this time of year, I get questions from producers on what stage cotton should be in. Cotton growth is closely related to heat accumulation, which is reflected as accumulated heat units since planting.

“Oklahoma is unique among many states because we have at least one weather station per county, and these are all linked together to form the Oklahoma Mesonet, a cooperative effort between the University of Oklahoma and OSU. Information is made available to anyone with a computer.”

The following instructions should give anyone access to the cotton heat unit calculator. First, go to This should get you to the main mesonet page, which will allow you to download a weatherscope program you will need later. Click on weatherscope download, when it comes to click run, you may need to click run again. When weatherscope has been downloaded, you can exit from the main mesonet site.

Then go to either or You will find a heat unit calculator key; click on this. Next click on cotton and then heat unit calculator. You will select the date of planting first and the current date next, then click run. The Oklahoma map will then be displayed with the number of heat units accumulated at each weather station. You can then locate the weather station nearest to you.

“As a general guideline, cotton should be expected to emerge at 50 to 60 heat units,” Banks says. “Pinhead squares should begin at 425 to 500 unit units from planting. First bloom is 725 to 825 heat units, and the first open boll should occur at 1,575 to 1,925 units after planting. The reason for the range in heat units for each stage of growth is the amount of stress the plants have been through prior to the growth stage.”

Bollgard II

Producers growing Bollgard II (BGII) cotton in specified areas no longer will be required to plant a structured, non-BT cotton refuge. After reviewing date submitted by Monsanto, EPA concluded that non-cotton crops and plants serve as a natural refuge for cotton bollworm and tobacco budworm moths. Thus, the presence of alternate hosts for insects and the efficacy of two Bt proteins in BGII sufficiently reduce the risk of resistance.

The natural refuge option is permitted in Oklahoma, Texas and Kansas when BGII cotton is planted. The natural refuge option is not allowed yet in several west Texas counties, however.

TALKIN’ COTTON is a feature of NTOK Cotton, a cotton industry partnership, which encourages increased cotton production in the Rolling Plains of North Texas, Oklahoma and Kansas. For more information on the cotton scene, check out and For comments or questions about Talkin’ Cotton, contact us at [email protected].

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