We experienced 31 degrees F for 2 hours, and 32 degrees F for 5 hours early on Monday morning here in the Levelland area. These temps were accompanied by an 10 mph north wind. This is what prevented a frost from developing.
Soil moisture kept temperatures in the cotton canopy slightly above freezing. The plants here are not dead but do have some injury and plant physiology is severely interrupted. It will be another day or so before we know the full extent of the freeze damage. I am not concerned with regrowth potential from this point on.
Add to this the fact that both daytime high and low temps are trending lower every day, and it would take several above average temperature days to allow the cotton plant to correct this. However, never underestimate a perennial plant. The cold snap I would liken to an application of paraquat at 1:30. A good conditioning treatment.
Obviously each field is going to be different, but from what I have seen so far, and based on the amount of green tissue remaining in leaves and bolls, ethephon will still work, the PPO defoliants (Aim, ETX, Display or Sharpen) will work, and desiccants will work. The ethephon treatment can go on at most anytime now, while the others need a more open weather window of 3-5 days. We should have that in a few days.
AgFax Weed Solutions
On grain sorghum it is not so easy. I do anticipate freeze injury in the grain sorghum head, as it is not as protected in a canopy. I suspect on grain that was well into dough it will make grain but could have light test weight. Anything younger than this, all bets are off.