As we get closer to defoliation, Dr. Camp Hand shares with us his recommendations:
“Looks like temps will stay in the 80s across the state this week, and in spots will go below 80 over the weekend. 3.2 oz/acre Dropp, 10 oz Folex, 32-42 oz/acre of Prep. Dropp rates should be increased in situations where there is already a significant amount of regrowth, or where regrowth potential is high. Additionally, if there is no regrowth, and low potential for regrowth, dropp rates can be reduced or it can be pulled from the tank. In cases where dropp is not in the tank-mix, I would increase Folex/PPO rates to get a better kill in the top of the plant.
By the time we get to Friday, I’d be thinking hard about having 12 oz/acre of Folex in the tank, 42 oz/acre of Prep, and Dropp in the tank. Additionally, I would think hard about using a Ginstar + Prep mix as opposed to the “three-way” mix I have outlined above. I’d be around 6.4-8 oz/acre of Ginstar in combination with 32-42 oz/acre of prep. I like an 8 oz/acre rate, but that is a little high for some folks’ taste. When using Ginstar, more dropp may need to be added to the tank if regrowth potential is high. As a reference, in 8 oz of Ginstar, there is only 1 oz of Dropp.”
There are many ways to determine the appropriate time to defoliate your cotton crop – 60% to 75% open boll, four nodes above cracked boll, and the ‘sharp knife’ method.
To determine percent open boll, count the number of open bolls and the number of unopened, harvestable bolls. Divide the number of open bolls by the total bolls and multiply by 100. For NACB, count the number of nodes from the uppermost first position cracked boll to the uppermost first position harvestable boll. When that number is four, on average, it is time to defoliate.
For the ‘sharp knife’ method, cut into the uppermost boll you intend to harvest and look for a black seed coat with developed cotyledons inside. Also, you want the lint to string out. Keep in mind that deer damage and severe plant bug infestations that were not controlled will likely delay maturity, thus checking your fields is of paramount importance.