Weekly in-season Updates
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INFORMATION |
June 10, 2007 Talkin’ Cotton J.C. Banks
The cotton plant is known as a slow starter and hopefully a strong finisher. Cotton is sensitive to all forms of stress while emerging and becoming established. This is the reason that 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. We are now beginning to get some heat, and 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 their 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. This is a cooperative effort between OU and OSU, and 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 http://www.mesonet.org. This should get you to the main mesonet page, which will allow you to download a weatherscope program that you will need later. Click on weatherscope download, when it comes up click run, you may need to click run again. When weatherscope has been downloaded you can go ahead and exit from the main mesonet site. Next, go to either http://NTOKCotton.org or http://okiecotton.org. 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. Pinhead squares should be initiated at 425 to 500 heat units from planting. First bloom is 725 to 825 heat units, and the first open boll should occur at 1575 to 1925 heat units from 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.
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