Frost on Cotton
Keith Edmisten - Extension Cotton Specialist
Many of you have had a frost and may be wondering what effect this will have on the cotton. A light frost will often help open bolls and defoliate the cotton. Once you get down below about 29 degrees the frost can have a negative effect on the cotton depending on the length of the frost and the age of the leaves and bolls. Younger bolls and leaves are more likely to stick as they have a higher mosture content than older leaves and bolls. By sticking I mean leaves will dessicate and stick on the plant for quite a while. For bolls that means they will not open.
A few days after a frost you can usually start smelling frost damged bolls when you cut them open. Hopefully this was a light enough frost for most of you and it will not harm harvestable bolls but help open them.
What do we do about defoliation and boll opening after the frost?
As noted earlier the frost may cause leaves to defoliate (especially older ones) or cause them to dessicate and stick (especially younger ones). I would not waste money on defoliants until you can tell what the frost has done. Shortly after the frost you will be able to tell if the frost had an effect. After 5-8 days you should be able to go out a thump leaves to see if the frost stuck them. If they fall of when you thump them then they will fall of naturally. If not they are probably stuck. Many times a frost will do different things to different portions of the plant. For example it may stick the leaves at the top, defoliate some of the top and middle and leave some leaves (not damaged by frost) in the bottom or the middle of the crop. In thiscase the producer will need to decide if enough non-frost damaged leaves are left to justify defoliation. Like deciding wether or not to pick through regrowth this can be a difficult decision. If they decide to pick through some remaining green leaf they can reduce the risk of color damage by using trailers, waiting until the cotton is dry and by using an oil based spindle wetting agent as opposed to a surfactant based agent. DO NOT WASTE DEFOLIANTS ON LEAVES THAT THE FROST TURNED TO CRISPY CRITTERS.
Hopefully most all the harvestable bolls were open. If you see the frost turn the bolls brown then there is no use in trying to open them with Starfire. They may only turn brown on the tops of the bolls but this is where the Starfire would have affected anyway.The frost has already done what starfire could have done (good or bad). Likewise, I see no use in trying to open frost damaged bolls with Prep. If you had a frost it either helped you or hurt you in terms of opening bolls and there is nothing else to do.
Back to the 1997 and earlier Cotton Notes
Carolina Cotton Notes CCN-95-11a November, 1995