Why are cotton bolls rotting before opening (kapas)?

Boll rot in cotton is mainly caused by fungi and bacteria in a dense, humid canopy, often worse after continuous rain and in lower bolls touching wet soil. Prevent it by keeping the canopy open, avoid excess nitrogen and very close spacing that make plants too bushy, and ensure good drainage so water does not stand. Remove and destroy rotted bolls to reduce inoculum, and control bollworms because their entry holes let rot organisms in. In high humidity a recommended fungicide spray directed at the lower canopy can help, but airflow and drainage matter more. Time picking so mature bolls do not stay wet on the plant. Confirm any fungicide with your local KVK before spraying.