Keep Young Cotton Out of Battle with Pigweed

Keep Young Cotton Out of Battle with Pigweed

Everything on the farm gets an early start in south Texas – including weed pests. As such, the last thing growers in the region need is for their young cotton to be pitted against invading pigweed on their home soil. It’s a losing proposition for the home team.

“The pigweed can get a jump on the cotton,” says Josh McGinty, Extension agronomist with Texas A&M AgriLife Extension Service in Corpus Christi. “And if the producer isn’t burning that field down at planting, they’re planting into a stand of pigweed. It may be little, and they may not really notice them, but they have an advantage already when that cotton is just seeded and there’s already emerged pigweed.”


“That does happen pretty often down here because we do warm up pretty early.”

The problem lies in the pigweed’s ability to remain inconspicuous in the first week that it emerges. The pesky weed will lay low and appear patchy – something that many growers may not recognize as an imminent threat.

In a scenario where the weeds are already established while a cotton crop is trying to make a stand, the cotton is going to have a lot of trouble competing.

“In the early season competition between a pigweed and a cotton plant, the pigweed wins every time if you don’t take care of it,” McGinty says. “They’re just more competitive. They get up so quickly once they get a little moisture – and that cotton plant, it’s slow. It’s a perennial so it takes a little while before it starts to put on a canopy. So the pigweed will take over pretty quickly.”

And in the warm early-season conditions of South Texas, the pigweed can grow more than an inch a day. With label-restrictions in mind, the window for spraying the early arrivers is “pretty narrow,” as McGinty says.

“We might only have a couple of days to catch them before they get too large,” he says.

So what can South Texas growers do to ensure their cotton doesn’t start off being bullied by pigweed? McGinty says growers would be smart to err on the side of caution.

“If they’re seeing any pigweed emergence, they need to go ahead and burn down that whole field,” he says. “My growers are getting very good at that. They’ll plant, and then they may come back in and spray a pre-emerge at the same time they’re spraying a burndown application of some sort.

“The growers who I’ve seen have the most success down here, as soon as they see pigweed starting to emerge, they’re already thinking about scheduling a spray,” says McGinty. “Those are little half-inch or one inch tall weeds, and they’re going to get a spray out there within a few days. That works. It’s more work, for sure, but it does work.”

McGinty recognizes that in South Texas, unlike other parts of the Belt, the early season is the most vulnerable time for a cotton crop.

“That first 8-10 weeks of cotton growth is the critical time,” he says. “That’s what I worry about as we get closer to planting.

“Getting that part right, at planting, does the lion’s share of the weed control that we need down here. Other parts of the country, because they get more rain, will have other weed problems. But our issues are right at planting for the most part.”


From Cotton Grower Magazine – February 2018