Carolina Cotton Notes - September 22, 2006

The newer herbicidal defoliants (Aim ET and Resource) do not tend to be rate dependent within temperature ranges normally seen for defoliation. This is similar to Harvade and unlike Def and Folex.
Low temperatures in general decrease the performance of hormonal defoliants more so than herbicidal defoliants. Hormonal defoliants include any formulation of Dropp alone or any epthephon product. Growers should not skimp on rates of these products where there use is justified.
The inclusion of an herbicidal defoliant in a mixture is more important in cooler temperatures. An example would be in hot weather you can defoliate well with Dropp alone or in combination with a rather low rate of an herbicidal defoliant. In cooler temperatures I would never rely on a hormonal defoliant alone. This can be accomplish with mixtures or with pre-packages products that include both hormonal activity as well as herbicidal activity. A good example of this is Ginstar which includes a hormonal defoliant (Dropp) and a herbicidal defoliant (diuron). It is amazing how much better Dropp works in a mixture like this than it does alone in cooler temperature.
We are moving into the transition period where we may still be worried about conditions favorable for regrowth but we should be finishing up the period of serious regrowth concerns in the next week or two. We will then move into a period where we are not too concerned about regrowth but may be anxious to open bolls before they are subject to possible frost damage. As we move into October we should focus on defoliation and boll opening and not worry so much about regrowth potential.