Cotton is ready for defoliation when the following conditions are met starting from least important to most important:
- Approximately 2/3 of the bolls are open
- The top bolls are within 3 or 4 nodes of the highest first position cracked boll. (4 NACB)
- The top bolls that will be harvested are difficult to cut with a sharp knife and the seed have no hollowness and a darkened or tannish seed coat around very light green endosperm and no jelly or liquid inside the seed coat.
- There is no tropical weather getting ready to sit on top of the field for multiple days with frequent and daily rainfall never allowing the canopy to dry.
Deciding on when to defoliate before a big storm or whether to wait until afterwards:
- Situation 1 – Wait until after the storm system or tropical event whenever it is supposed to last for an extended period by stalling out.You would not want to defoliate and have a bunch of bolls in the cracked stage.
- Situation 2 – Spray in front of the storm when it is expected to be moving fast, not last more than a day or so, and has extremely high winds that will tie up the cotton making it more difficult to get the field sprayed afterwards.
- Situation 3 – Most or all of the harvestable bolls are already open.Then it would be better to defoliate right in front of the weather event so that that job is taken care of.There would be no further risk of hardlock in this situation and the leaves would not start coming off for several days after spraying.
Hurricane Florence is predicted to be most like situation 1 for our region. Even though the high winds could come, the risk of cracking the bolls is more of a concern unless all your cotton is completely open. Most cotton is not ready yet anyway.