WEST PLAINS IPM UPDATE
COTTON- Let us look at what the average cotton plant looks like based on what I am finding in the scouting program: • Average number of total nodes
• Average number of total nodes is 15 (range 11 to 19)
• 1st fruiting branch at node 7.2 (range 5-10)
• Square retention of 1st positions is 91% (range 80-99%)
• Node length is 0.8" (range of
0.7"-1.4")
• Plant populations average 36,300 per acre (range 23,000 to 49,000) • Nodes Above White Flower 5.5 (range of 2 to 9)
• Average 1st position bolls per plant 1.1
I continue to see more blooms and small bolls daily. However, I am also seeing way too many fields blooming out the top. I know this may be unavoidable in some fields. On the other hand, if you can prevent it from happening for a few more weeks your yield potential will improve greatly. I addressed this in last week’s newsletter. So, available moisture or the lack thereof is driving this thing. If you have adjacent fields sharing water resources and one or both fields are closing in on 5 or fewer nodes above white flower (NAWF), I suggest diverting more water to one of the fields. Yes, this will sacrifice potential on one but maximize on the other. Many other situations are occurring out there were water is not going solely to the cotton crop (i.e., trying to get a sorghum crop established at least for cover). This diversion of water is really going to hurt your cotton prospects. Do Not Do It! Keep the water on the cotton as best you can for as long as you can. We are going into the cotton crops greatest water consumptive period, and it is showing in this drought. No insect issues more important than this tilizer applications need to be wrapped up soon if not already. More on Irrigation- Most years it seems as though irrigation management here in our neck of the High Plains is simple - you turn it on, and you do not shut it off. Unless of course it rains, or it is late August to mid-September, then you may shut it off. However, this is a terribly unusual year, and many are wondering when they can start backing off or just shut the water off. So first, before I give my annual example of when to stop irrigating, let me say that I understand the desperation that many are in and literally cannot water any longer. Also, you are the owner of your farming enterprise, and it is your prerogative to make any decision you feel necessary.
The NAWF measurement can be helpful. This will let you know where your current top boll position is and how old previously set bolls are. As an example, if we have a white bloom three nodes down from the top, I will say you have 2 NAWF. Now I am only referring to first position fruit.
So just below that white flower should be a small boll which would be approximately 3 days old. The boll directly below it was formed 60 heat units before this small boll. Which on average this year is 2.7 - 3 days. So, if there are a total of 4 first position bolls, we can estimate that the oldest boll is somewhere around 12 days old right now (the only boll which may not come off). The oldest boll would have been a bloom around July 16th. Okay, now that you know how to judge the age of a boll you should consider which of the uppermost bolls you can realistically take to harvest. Let us say that the current white bloom up near the top is the last one we think we can hold based on the drought. Okay then, this flower will be a boll in a day or so. This boll cannot be water stressed for about twenty days. So, this plant needs good water through August 17th. Now this moisture may come from irrigation or rain. After August 18th this boll can take moderate stress, meaning that it can wilt down on a hot afternoon if it completely recovers the next morning. By September 13th or when this last boll is about 45 days old it can take severe water stress and it should not cause quality or yield loss. Remember also, that until a small boll is 7-10 days old it can easily be shed when the plant is put under stress.
So, there you have it, with the drought we will already suffer yield and possibly quality reduction. However, if you turn the water off too soon you are guaranteed to cause additional if not total loss of yield and quality. I would much rather see you try and keep up with portions of a field rather than shutting a whole field off. Unless of course it is a scenario where irrigation water is being shared with another field. Then it may be the right thing to sacrifice one field for another.
West Plains IPM Update is a publication of the Texas A&M AgriLife Extension Service IPM Program in Hockley, Cochran, and Lamb Counties. Editor: Kerry Siders, Extension Agent-IPM Contact information: 1212 Houston St., Suite 2 Levelland, TX 79336 (806) 894-3150 (office), 638-5635 (mobile), or 897-3104 (Fax) ksiders@tamu.edu (E-mail)