Weekly in-season Updates
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INFORMATION |
July 25, 2005 Talkin’ Cotton
Hot weather has arrived and where cotton has moisture it has responded with rapid growth and fruiting. Irrigation is on full schedule for those who have water; cotton is using some of the subsoil moisture received in early spring in dryland areas. Most dryland areas started stressing for moisture this week; hopefully we will get a rain soon. I have received some questions this week on how long it takes to make a boll and does late planted cotton that has been under stress have time. Cotton growth and development is controlled by heat units received, but we can get reasonably close by counting the number of days. From pin head square it requires 21 to 23 days to produce a white bloom. In one to two days the white bloom will turn red and fall off. This is officially when the fruiting form becomes a boll. Boll development from this stage to full maturity requires 50 to 55 days when the boll opens and is ready for harvest. The fiber elongates and develops maximum length during the first 16 to 18 days following bloom drop. Any severe stress during this period can cause short fiber content. The extent of short fiber will depend on the number of bolls that were in this critical stage when the stress occurred. Micronaire, or thickness of the fiber, develops after fiber length occurs. Low micronaire problems occur when fiber development is stopped before the boll fully matures. This usually is a result of cool weather late in the development process. Now we can get back to the question of “does this crop have time to mature”. In most areas of Oklahoma we have our first freeze near the first week of November. We normally receive very few heat units during the last week of October so fiber development will be terminated at this time. Since fiber needs to be mature the last of October, and development from bloom requires 50 to 55 days, a September 1 bloom should have time to mature under normal conditions. Since a pinhead square requires 21 to 23 days to become a bloom, a square that is formed in the first week of August should have a good chance of developing into a harvestable boll. Cotton that is blooming the first week of August will normally have at least 6 to 8 squares above the bloom. Weather conditions in August will determine how many of these bolls the cotton plant will keep, but at least this gives us an idea of the “potential” of our crop.
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