From the October 2018 UGA Cotton Team Newsletter
When to Stop Irrigating Your Cotton Crop
Throughout 2018 the Georgia cotton crop has been extremely variable in regards to growth and development. This is due in large part to heavy and frequent rains during the planting window. Even now we have the crop in various growth stages ranging from cotton being harvested, defoliated, starting to open, and our latest planted crop unopened and still needing additional irrigations in some dry regions of the state.
Deciding when to terminate irrigation is one question that has come up quite frequently in recent weeks. The general recommendation is to stop all irrigation events when 10% of the bolls have opened. (This is usually about 1-3 bolls per plant.) This can help with issues such as boll rot, hard lock, as well as preserve fiber quality. There MAY be times when irrigation beyond this point is warranted. Scenarios where fruit retention on the lower nodes is poor and most of the harvestable bolls are located on the upper nodes may require additional irrigation water. However, all factors such as current and future weather conditions and available soil moisture must be considered.