The cotton crop is off to a late start and is struggling in many areas. The use of mepiquat (Pix) can be more important with a late crop than a “normal” crop. This is because mepiquat can make cotton mature earlier. This could be important this fall since the crop is averaging being about 2 weeks behind. The excess rain has made it difficult to make applications and made it difficult to make mepiquat decisions when the weather has allowed opportunities.
I have looked at cotton that is close to 30 inches tall and a week or two from blooming and I have seen cotton that is very stunted due to excess moisture. The cotton that is is 30 inches tall prior to bloom obviously could use some mepiquat as soon as the weather allows. I would wait on the stunted cotton to resume normal growth when things dry out. We would like to see that cotton get some fruiting sites (nodes) before we risk decreasing growth.
Of course there is often some of each of the cotton I have described above in the same field. This would be a great place to use a wick applicator if you have one, otherwise you are stuck trying to cut the sprayer on and off. Where this is not feasible I would tend to go ahead and put 3/4 the rate suitable to the taller cotton on the entire field and be ready to treat again soon.