Chop Pigweeds Now, Before It's Too Late

 

By: Brad Haire, SouthernFarmer.com
6/20/2012 10:41:50 AM

 

The field was clean. The best practices used at planting. The herbicide program applied, all as timely as possible during this year of extreme weather. But still, as you look over the cotton field now, you see them, Palmer amaranth weeds, standing tall, getting bigger by the day. The only course of action now is to go manhandle them out of there and save the crop and to keep a bad thing from getting worse next year.

"I think we've tilted the scale back to your favor as far as Palmer control. Our growers are making intelligent management decisions. They are at war and going after it. The key is accepting it is going kick your tail sometimes, but then going back and making the right management decision again," said Stanley Culpepper, weed specialist with the University of Georgia Cooperative Extension.

If Palmers are popping up, the trick, or the right management decision now, is to get out there and remove them before the weed starts producing seed, which most growers should now know it can do at an amazing level. But Palmer seeds are weak and don't last long in the soil, the only edge this weed gives to growers. "If they are seeing just 10 plants per acre, it is important to get those plants," he said. "And with good hand weeding, and if done right, we can see a significant change in the seedbank in just three or four years," he said.

Culpepper and Lynn Sosnoskie, a former UGA College of Agricultural and Environmental Sciences postdoctoral associate now at the University of California, conducted research to see how effective hand weeding at cotton layby can be in controlling Palmer's seed bank.

Basically, a unchopped Palmer will produce near 400,000 seeds in dryland cotton production. One chopped to six inches will regrow and still produce 130,000 seeds. If you get it down to one inch, it still produces 36,000 seeds. And, finally, if it's chopped all the way to the soil, well, it still regrows and gives you 22,400 seeds.

"Even if you pull it up, it can still resucker if any part of the root touches the soil. ... You have to get out there and not just whack it off but remove 100 percent of the above ground plant but really you have to get those roots in the air as much as possible or get it out of the field," Culpepper said.

It is important to remember that it is all a numbers game. If herbicide resistance can be found in that one plant in a million or even 10 million, then you don't really need that much cotton acreage to find it. In samples taken from 100 growers' fields in Georgia, having 25 pigweed plants emerge per square foot was common.

To find that one resistant one, in this case you only need 9.18 acres of cotton. "But let's just say that resistance happens in just one in a billion plants, still then you only need 918 acres of cotton to get it," he said.

 

For more information:  http://farmprogress.com/southern-farmer-story-chop-pigweeds-before-too-late-9-60791