Cotton Maturity Update and Defoliation

Author: Scott Stewart, IPM Extension Specialist Comments Off on Cotton Maturity Update and Defoliation

If you look at the DD60 accumulations for Jackson (see Quick Links), you will see that we have now accumulated 350 DD60s since August 15th. This means insecticide applications should be terminated. A rare exception would be where spider mites are present is levels high enough to defoliation during the next 10 days.


It takes roughly 800 DD60s before the last, potentially harvestable bolls … those present at NAWF5 or August 15th, whichever came first … will be physiologically mature. This means we need a warm September for late maturing fields. Fortunately, the recent weather has been cooperating and the crop is progressing nicely.


It is likely, based on typical September weather, that we will accumulate another 350 DD60s or less by the end of the month. Even though the top bolls may not be completely mature in late fields, a good rule of thumb is to begin making applications of harvest aids no later than the first few days of October. It is important to get harvest aids applied in time to work before our first frost, which typically occurs in mid October. I’m no defoliation experts, but those in the know are strongly suggesting a two-shot approach (especially in late maturing fields).

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