What is in this article?:
- For less soybean injury, run planter after spray rig
- Let planter chase spray rig
- Burndown window is expanding
- Cover crops a weed control option
Making a herbicide application after the planter has already gone through the field often involves “a very narrow window of opportunity, especially when temperatures are warm,” says Tom Eubank, assistant Extension and research professor at the Delta Research and Extension Center, Stoneville, Miss. “The approach I advocate is for the planter to chase the sprayer, and where farmers used this approach last year, they didn’t have nearly the injury issues we saw when we were making an application behind the planter."
BILL LONG, from left, DuPont Company, Greenwood, Miss.; Bob Stonestreet, Clarksdale, Miss., consultant; and Tucker Miller, Miller Entomological Service, Drew, Miss., were among those attending the annual conference of the Mississippi Agricultural Consultants Association.
Let planter chase spray rig
“A lot of farmers have called me and said weather kept them from making these applications. The best way to avoid this scenario is to make the application prior to planting. Even if you do it four or five days before planting, that’s better than making an application after the planter, in my opinion. Your spray rig can go a lot faster than your planter can go.”
Another point to consider, Eubank says, is that if these residual herbicides are applied earlier, then their length of residual will be shortened in-season. “This will necessitate that the first over-the-top herbicide treatment be moved up as well, and also that an additional residual herbicide should be included. Again the benefits are many in that applications of residual herbicides applied over-the-top are much less injurious on smaller soybeans. “Additionally, there is a greater chance these residual herbicides will contact soil, were they are most effective ,as opposed to being intercepted by the crop, and in many cases rendered ineffective.”
Two problem weeds, horseweed and Italian ryegrass, require that an effective herbicide program be used, Eubank says.
“For horseweed, we’ve been using glyphosate and 2,4-D or dicamba combinations, and these programs have been fairly successful. But we’re starting to see increased tolerance to these combinations.
“Dicamba rates have increased incrementally over the years. In Mississippi, we’re now using about 8 oz. of dicamba, but in Tennessee, Arkansas, and Alabama, they’ve had to increase rates to 10 oz. to 12 oz. to get an effective level of control of horseweed.
“Even though we’ve not yet documented dicamba resistance in horseweed, it’s highly suspect that we may be coming to that point in the near future.”
Farmers using combinations of dicamba, 2,4-D, and glyphosate, are getting somewhat better control, Eubank says.
“I like the combination of glyphosate, Sharpen, and 2,4-D on horseweed. If you can catch the weeds early, adding Sharpen really beefs up the 2,4-D and you can control somewhat larger horseweed with this combination.”
Closer to planting, he says, “I’d recommend a paraquat plus metribuzin combination, which works well. With this combination, you get a synergistic effect and better control. An added advantage is control of emerging pigweed.”
With paraquat, Eubank says, “Coverage is essential — you need a good water volume and fine droplets to get the spray down into the growing point.”