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Agronomic Crops > Crops Blog > Posts > Managing this "Split Crop" of Cotton

Every year brings its own challenges to the farmer.  Every year the weather patterns are an unknown and even with the best plans such as: when we plant and what we are going to do and how we are going to accomplish it, those plans always somehow seem to get rearranged.  For 2018, it really seems to have been a very challenging spring to get the crop planted and emerged in the time period that we wanted to plant the crop. It has also been a very challenging spring to manage the first post emerge weed control spray.  The cooler than normal April delayed many farmers from planting until early May.  When May got here it went from cool to hot and there were no spring planting showers to keep the planters going.  Some farmers continued to plant while others stopped the planter because of dry soil conditions.  When the rains did start back in the later part of May they did not shut off until we got well into June.  This was a condition that I refer to as the year of the "light switch May".  It was dry and just like that it was wet.  As a result this has created a "split crop" for us in Alabama.  I was traveling last week in southwest Georgia and it seems that their crop is not as divided as our crop is in southeast Alabama.  The end result is an early crop which I estimate to be around 50 percent and a late crop being around 50 percent.   With this split crop this certainly presents a challenge when making management decisions.  With the earlier planted crop we should be very familiar with crop management of fertilization, weed control, growth regulator use, etc.  However with the later planted crop, it is here where I feel that we must not be lulled to sleep thinking that this plant is just like the cotton that was planted in late April or early May.  On the earlier cotton we are subject to split apply fertilizer and sometimes not be as aggressive with our growth regulator applications.  The crop has "time" we feel like to basically manage itself somewhat and still make it to the finish line.  The later planted crop which has been planted in late May through late June and some even in early July is a different animal than the early planted cotton.  It may not seem like much but being just a month or more later planted really is a very different crop. Cotton is a 150 day crop basically and develops on heat units, typically around 2500 growing degree 60s.  The early crop is slower to develop because of cooler temperatures.  The later planted crop has much higher growing degree 60s therefore it will change rapidly.

The management for the later planted cotton should be one of urgency.  All the nutrients such as nitrogen should be applied early.  Early is somewhere in the 3 to 6th true leaf.  Especially dry land cotton.  The reason being is because we are in July and it may not rain for two weeks and the nitrogen doesn't activate until you get the rain and the whole time the cotton has been deficient of nitrogen, therefore slowing its growth and development.  This is time we do not need to give up on producing this crop.  Also, the management of growth regulators is also very important.  The very best growth regulator is actually a cotton boll itself.  Once the plant begins to load up in fruit the cotton plant is relatively easy to regulate with a growth regulator.  Remember cotton is a perennial and we manage it as an annual and often we need growth regulators to channel the plant into a reproductive commitment.  Otherwise the plant likes to grow vegetative.  Some varieties are more indeterminate than others therefore the utilization of a growth regulator is more important.  Stress conditions can also channel the plant into more of a reproductive phase.  That's why the application of a growth regulator is more of an art than a science.  However, we know that using them is important and the take home message is this late planted cotton doesn't need to grow unchecked in the vegetative stage because the time to make this crop is in a narrower window.   We have the time, we typically have the heat units to make an excellent late planted crop of cotton but we do not have the luxury to mismanage the crop and still be fine.

Another item of concern is that this later planted crop will reach peak water demand somewhere around the first of September, which coincides with the peak bloom being roughly 90 days after planting.  September is historically the second driest natural rainfall month for Alabama with October being the historical driest month of the year.  This certainly concerns me when considering the dryland late planted crop.  Nobody has the crystal ball to see the future, but my message is to manage with urgency to not sacrifice any heat units in producing this crop by managing all aspects without delay.  

William Birdsong

Ext. Regional Agronomist, Auburn University, Wiregrass research and Extension Center



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