Cotton has had fairly good weather the last few weeks. Sure, many of you could have used a bit more rain, but all in all despite how we have heard the weather forecast saying it is going to be hot, the temperature range has been very good. No doubt irrigation has been critical since the last week of July but thank God it was not early June. Irrigation applications are still critical currently. The cotton plant is still at peak water use for a while longer. This brings up an important point. We are at or very close to the end of the blooming cycle, at least effective bloom, and creation of bolls (harvestable and mature). From this point forward it is all about retaining those bolls, achieving good size for yield and good quality.
Always remember that we are dealing with a perennial plant in cotton. Any late growth will not have time to contribute to yield and in fact can detract from what is already there. Also, a growth regulator cannot fix that situation. Along these lines, and to support what my point is here, we are now seeing the adjustment in fruit load in many fields. This adjustment causes squares and young bolls, less than 5–7-day old, to be shed from the plant. This is a natural process which occurs when the holding capacity of the plant has been reached. Of course, we want to be certain it is not insect induced losses, or it can be induced by a well going down in an irrigated situation. That capacity is set by the plant which has been developed, soil nutrients, soil moisture, production of carbohydrates within the plant etc. Based on those parameters the plant can produce only so much, until something changes. When these changes, like a big influx of soil moisture (or late fertilization), occur late it can cause the plant to resume vegetative growth.
This directs energy into creating additional nodes, stems, leaves, and subsequent squares. This late growth will run out of heat units before it can develop into good contributing mature bolls. So, be careful with any inputs provided and how the plant will react to those inputs.
Cotton aphids have rebounded here the last 10 days or so, attracting attention again. We have had an ideal situation for aphids – skippy stands, maybe late N applications, etc. Keep scouting and make sure the beneficial insects, which have been present in great numbers will do their job. If not, you may have to treat. Besides aphids Lygus, and stinkbugs are still present in good numbers and may cause economic loss. YOU MUST SCOUT THOUGH TO BE CERTAIN!
In grain sorghum the sorghum aphid (aka. sugarcane aphid) has not been noted but the yellow sugarcane aphid has. Headworms and stinkbugs are highly variable from field to field. Again, you must scout each field. No blanket generalizations here.
My priority list for August goes like this:
1. SCOUT! SCOUT! SCOUT! Lygus, stinkbugs, and cotton aphids have been about as active across a wide area this year as I have seen in many years. Scout, apply threshold, act on good information.
2. Continue with late season weed control: residual herbicide, cultivate, hoe, whatever it takes to keep weeds from going to seed, especially Palmer amaranth. It is a numbers game.
3. Be careful when irrigating not to cause additional vegetative growth resulting in delay of plant maturity. The goal is to finish blooming before the end of August.