Sun Scald in Cotton
In the picture below you can see leaves that have curled up and “scalded” or “sunburned” on the lower side of the leaf.
This typically happens when we get a short rain on a hot day and then it immediately turns back hot. It may also occur when the cotton is sprayed (as is the case in the cotton above) on a particularly hot day.
You can also see leaf spot diseases in the picture below (photo 2). These are fairly common on drought stressed cotton due to the stress and the lack of Potassium available to a plant during drought. It seems that fields like this are more likely to show symptoms of sun scald, probably because due to the lack of moisture the plant cannot cool off the leaves as well.
You can also see premature defoliation in the picture at the bottom of the page (photo 3) taken from the same field. This is also likely due to stress and lack of Potassium. Potassium uptake is dependent on moisture movement into the plant. During droughts we sometimes see potassium deficiencies even where adequate Potassium fertilizer was used because the plant cannot take up Potassium in the absence of moisture.
Photo 2
Photo 3
Photos taken by Paul Smith
2007 - Carolina Cotton Notes
