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25
May
2012
Thrips, Pigweeds and Ugly Cotton: What Do They All Have in Common
Author: Gus Lorenz, Extension Entomologist

Thrips have been absolutely terrible this year. Obviously numbers are very high, but the most important part of this equation is that the cotton isn’t growing, and that’s what’s made the thrips a problem. When cotton is healthy, it can usually outgrow thrips, but this year the slow growing cotton has forced many growers to make multiple applications to control thrips. To make the situation worse, we have western flower thrips, or WFT, that are harder to kill than our traditional dominant thrips, tobacco thrips.  As a result, many growers are experiencing control failures with  standard treatments such as acephate and bidrin and are having to change to Radiant,  which is twice (or more) as expensive. Radiant has been very effective on the WFT, but at 68-cent cotton, you have to wonder how much money we can spend on thrips control.

The long and short of it is that the cotton just isn’t growing well. Pressure from thrips is high and disease incidence is high, so, what’s going on? You have to wonder how much of this is related to all the herbicides we are putting out there to control those dang pigweeds. Most of us with a little gray hair on our head remember what cotton production was like before the Roundup Ready era, when we were using PPI’s, pre-emerges, and direct spraying under 3-inch cotton to control weeds. 

Herbicide damage was common place back in those days. Then the R-U system came on line and we aren’t doing any of that. We are just spraying Roundup over the top. I can’t help but feel like all these herbicides we are spraying are severely affecting growth which is impacting all the pests like thrips, seedling disease, and nematodes.

I’m hearing a lot of grumbling about insecticide seed treatments (IST) not working, and if we are going to have to spray thrips, why pay for the insecticide seed treatment? We have plots this year without seed treatments right beside cotton with the IST’s and I can tell you there is a big difference. True, they have to be sprayed, but they are providing some control, and you can see the difference, make no mistake about it. Admittedly, they aren’t providing the same level of control they were a few years ago –before resistant pigweeds. You have to wonder how much impact all those herbicides we are using to control pigweeds are making on the efficacy of our IST’s and fungicides. Aldicarb coming back on line for next year may prove beneficial for many growers next year. That’s what we had back in the day that helped us over the hump with herbicides.

Here’s one more idea, with all this dry weather and the slow-growth situation, when someone asks me about making yet another thrips application, instead of spraying again, how about running some water down the row and try to kick-start some growing cotton to outrun the thrips … just a thought.

The bottom line on all this is, we need to get a handle on this situation quickly, the future of cotton production in the Mid-South depends on it.

 


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