What is in this article?:
- Four bract square phenomenon in 2011 cotton likely temperature-related
- Better quality choices than ever
- Know weed species in field
“When we started getting reports of squares on the ground in 2011, our first thought was plant bugs,” says Darrin Dodds, assistant Extension professor of plant and soil sciences at Mississippi State University. “But when we looked more closely, we found the shed squares were mostly four bract squares. Research regarding four bract squares points to high temperatures as the cause, rather than insects."
PATTON EMBRY, from left, Worthy Pest Management, Eupora, Miss.; Chris Adams, Adams Crop Management, Winona, Miss.; and Kobin Worthy, Worthy Pest Management, Cadaretta, Miss., were among those attending the annual meeting of the Mississippi Agricultural Consultants Association.
Know weed species in field
“It’s important to know which weed species are in the field and their growth stage when making applications. You can’t melt down a six foot tall pigweed with Liberty the way you could with Roundup before resistance showed up.”
Dodds cautions that “we want to be careful not to over-use Liberty. It’s a very valuable tool in cotton, and if resistance develops to this chemistry, it would put us in a very difficult spot, relying heavily on PPOs.
“We’ve already seen resistance in some related weed species in the Midwest, and it could show up here. We need to look at Roundup as an example of how not to use Liberty. Let’s be a bit more judicious in our use of Liberty in order to try to prolong the life of that technology.”
Trait technologies in the development pipeline “will present some unique challenges,” Dodds says. “The dicamba and 2,4-D technologies are very interesting, but certainly the biggest issue with them will be keeping them where they’re sprayed and off neighbors’ fields.”
A grower’s choice of seed treatments should also be carefully made, he says.
“We talk a lot about insecticide traits and herbicide traits, and it’s often easy to overlook what’s on the seed — but that’s certainly not an unimportant decision.
“Over the last decade, seed treatments have become the standard, and there are numerous options available, from insecticide to fungicide to full packages plus a nematicide.” While different varieties may include many of the same treatment components, Dodds says beyond that the question is whether to use a nematicide treatment.
“Several years ago Gabe Sciumbato, plant pathologist at the Delta Research and Extension Center, and others did a survey in the Delta and found about 33 percent of the surveyed acreage infested with reniform nematodes.
“If you have 333 acres infested out of 1,000, figuring a 10 percent yield loss on a 950 lb. state yield average, you’d lose 95 pounds per acre, or 31,000 pounds total. At $1 per pound, that’s $31,000 lost to nematodes.
“If you reduce that loss by 50 percent with a nematicide seed treatment and other management practices, such as irrigation, you’ve just gained almost 16,000 pounds, or $16,000, which is a really great return on your investment.”
Some growers, he says, are not happy that “I spent money on soil sampling and didn’t find any nematodes, so I wasted that money.”
“My argument is that if you didn’t find any nematodes, you can eliminate a nematicide seed treatment, a savings of $6 to $8 per acre, which is a three- or four-fold return on your cost for soil sampling. And knowing whether or not you have yield-limiting levels of nematodes is worth making that investment.
“I would suggest matching seed treatments to the needs you have. If you have no treatable level of nematodes, then just choose an insecticide and fungicide seed treatment. Some of your choices there will be dictated by the brand of seed you choose.
“If we get a season like 2011 that was cold and wet for a long time, and cotton seed sits there in those conditions for a long time, results likely will be less than optimum. A lot of folks weren’t happy with the way their seed treatments performed in those conditions last year.”