Weekly in-season Updates
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INFORMATION |
July 18, 2005 Talkin’ Cotton Causes of Fruit Shed It is important to do all we can to ensure that developing bolls will stay on the plant, but due to the perennial nature of the cotton plant, it will adjust the fruit load according to prevailing conditions. Approximately 21 days from pinhead square, a bloom should appear on the fruiting site. During this 21 day period, the plant will abort a square due to stress only during the first few days following pinhead square stage. During the squaring stage, most fruit loss will be due to insect damage, but very severe stress at the beginning of the square stage can cause loss of pinhead and smaller squares. The development stage most sensitive to environmental stress is the first 10-14 days following bloom. The plant makes a decision at this time if it has enough nutrients and moisture to mature the boll, and if it is under stress, the small boll will be aborted. It is also at this stage that bollworms can damage the small boll enough to cause abortion. At about two weeks after blooming, stress shed will be greatly reduced, but larger bolls can be lost due to insect damage. If the plant sustains a large boll loss, it’s natural tendency will be to produce a surge of vegetative growth as soon as the source of stress is removed (rainfall). The plant can go into a sustained growth period of vegetative growth, which will develop a tall healthy looking plant, but with only a few bolls. In most cases, as soon as the stress is removed, an application of a mepiquat type growth regulator should be made to redirect plant development from vegetative to fruit development. Applications should be made as early in the fruit development period as possible. Late season applications of growth regulator are seldom effective. Under ideal conditions, as the boll load builds, the plant will start shedding squares when the yield potential of the plant is being met. If the cotton plant has a good fruit load, a slight deficiency in moisture, nutrients, or even a few cloudy days can cause small bolls to shed during the first ten to fourteen days following bloom. Under high fertility and good moisture conditions, the plant will retain more bolls during the critical period resulting in higher yields. Very late season stress will rarely result in shedding of large green bolls, but fiber quality likely will be reduced.
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