Weekly in-season Updates
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INFORMATION |
July 4, 2005 Talkin’ Cotton
We’ve been getting questions on two somewhat related items, use of growth regulators and use of foliar fertilizer on cotton. There have been several foliar fertilizer products lately promoted for supplemental nitrogen use on cotton. These products contain 9 to 28 percent nitrogen and are recommended to be applied up to 1 gallon per acre on seedling cotton and up to 3 gallons per acre on cotton during the full leaf, boll development stage of growth. We have looked at some of these materials and they do boost nitrogen available to the crop, but should be used only as a supplement if soil available nitrogen is not enough during an especially heavy fruiting period. Most nitrogen needs should have been taken care of with soil applied materials because the price per unit of nitrogen is much lower, and a greater amount of materials can be applied without injury to the crop. It is commonly accepted that foliar feeding can make a good crop better, but it cannot make a poor crop good. Some claims are made that these materials will help stressed, wind injured, or hailed on cotton overcome the stress more easily. A material may be applied, and with favorable conditions the crop may start growing, and we give credit to the application material instead of the favorable weather. We need to remember that an injured or stressed leaf will not absorb any foliar fertilizer effectively. Even the herbicide Roundup has label restrictions that weed control will be decreased when applied to stressed weeds because they cannot absorb the herbicide. Dryland cotton will seldom need foliar fertilizer unless a lot of moisture and heat is received during the boll development period in early to mid-August and inadequate fertilizer was applied to meet yield predictions.
Now is the time to consider plant growth regulator (PGR) application to cotton. Growth regulators can be any product that contains the active ingredient mepiquat chloride, there are several generic brand names, and active ingredient concentrations may differ for trade names, but the most common materials will contain .35 lbs per gallon of mepiquat chloride. If dryland cotton can set and hold early bolls, a growth regulator is seldom needed. Our August weather normally does a good job of regulating cotton growth in dryland conditions! If for some reason, the cotton has lost it’s bottom crop, an application of a PGR may be needed to throttle plant growth and re-direct growth from vegetative to fruiting. If an application is needed, do not apply to drought stressed cotton, because it may result in excessive fruit shed. Irrigated cotton can normally benefit from an application at first bloom or just prior to first bloom. At first bloom, the number of nodes (or branches) above a first position white flower can be determined and if this number is seven or less, little or no PGR will be needed. If the number is above seven, the crop will usually benefit from a PGR application. If you need advise on rates for a particular field call me at 580-482-2120. |