What weeds are lurking in buffer areas?
Resistant weeds will be difficult and more costly to control in buffer areas required for Xtend and Enlist technologies, particularly when buffers extend into part of a crop field, say weed scientists.
“It certainly is a concern,” said Aaron Hager, associate professor of weed science, University of Illinois at Urbana-Champaign, especially “if those herbicides (2,4-D and dicamba) are being used because glyphosate and other products are no longer effectively controlling the weeds in those areas. If the weeds are left uncontrolled, they’ll basically be a nursery for weed seed.”
The buffer requirement, if anything, is ironic from a weed management standpoint, more than one weed scientist has pointed out.
Bob Scott, weed scientist at the University of Arkansas says buffers may be the law, but the concept runs counter to best management practices established by the Weed Science Society of America because they reduce herbicide options for farmers.
“The whole idea of a buffer means that you’re leaving a repository for weeds to come up,” Scott notes.
Spelled out in extensive detail on labels, the buffers are designed to minimize herbicide drift to sensitive areas. Depending on rate, herbicide and type of sensitive crops nearby, buffers can extend 30 to 220 feet from a sensitive area or crop. In some cases, buffer requirements may prevent a field from being sprayed.
Will you have to maneuver in and around buffer requirements this year? Below are 7 tips to take into account.
#1. Wind direction – it pays to check throughout the day.
Because buffer location is determined by wind direction, producers won’t know where a buffer is until the day of spraying. “You need a plan for when you have wind and when you don’t have wind,” says Larry Steckel, weed scientist at the University of Tennessee. “Ask yourself if the field is close enough where you can conveniently come back to spray the buffer when the wind switches in two days. Or is it in a field three counties away from your operation? In that case, you need to have a Plan B.”
Another complication could occur if wind speed or direction changes abruptly during an application, Hager points out. “What if you’re making an application in June on a 120-acre field? At 7 p.m., when you’re halfway through, the wind stops. How many applicators are going to recognize that when they’re in a cab doing 12 to 15 miles per hour? Are they going to stop and check for temperature inversion conditions?”
#2. Use residual herbicides.
A recommended preemergence rate of residual herbicide all the way around the field perimeter could help control weeds in potential buffer areas, Hager says, “but if you’re dealing with a species like Palmer amaranth or waterhemp, the idea of trying to get season-long control from soil-applied herbicides generally doesn’t apply.”
Hager says for pigweed species in Illinois soybean production that farmers “still have some fairly good activity out of the soil-applied PPO-inhibitors, like Valor- and Authority-containing products. But we always caution farmers that if you use an ALS-inhibitor product with a PPO, you have only one effective herbicide in that mix simply because of how common ALS resistance is in our waterhemp population.”
Don’t cut the rate to cut the cost, Hager stresses. “It’s a time of low commodity prices, but cutting the rate could lead to reduced revenue if you’re losing bushels in the hopper.”
“The problem is that residual herbicides play out,” Scott observes. “They’re inconsistent, and they will never be the answer for complete season-long control. Having said that, we recommend them on every acre, no matter what the technology.”
#3. Keep a dedicated sprayer for buffers.
You’re getting ready to spray a field with Xtendimax and realize that you may have to lay off the downwind side of the field by 110 feet. There are resistant weeds in the field that you won’t be able to spray. You can come back a day or two later and spray if the wind is more favorable. But if you absolutely need to spray that day, consider dedicating a buffer sprayer to control those weeds.
“Hopefully, you would be able find a herbicide that would still control the spectrum of weeds that would be in there,” Hager says.
#4. Weeds In buffers – chop them out or cultivate if you can.
If you don’t have a herbicide option or can’t get back into the buffer in a timely manner – and resistant weeds are present –remove the weeds by hand or cultivate if you can.
“The worse-case scenario is that there’s not a postemergence herbicide option,” Hager said. “If that’s what you’re up against, it’s time to sharpen up hoe, because at the end of the year, if you let those surviving plants produce seed, you’re going to be dragging that seed all over the field when you combine the field.”
#5. Consider planting corn in buffers.
Xtendimax and Engenia are labeled for preplant, preemergence and postemergence applications in corn, and no buffer is required. A quarter-pound active ingredient of dicamba can be applied up to 30-inch corn. A half-pound of active ingredient, which is the standard Engenia and Xtendimax rate of 22 ounces, can be applied up to 5-inch corn.
“I’ve talked to some cotton producers who are thinking about planting corn around the edges of fields to serve as buffer areas or to give them some drift protection,” Steckel said. “There may not be a lot of that, but I think we’ll see a few farmers play with the concept a little.”
The buffer corn crop could be harvested, “but you’re going to run over it a lot when you’re spraying your insecticides on cotton,” Steckel said. “So how good the corn will be is debatable.”
So why is there not a buffer for corn? “I don’t know,” Steckel says. “No one has explained it to my satisfaction.”
#6. Communicate with neighbors.
You may be able to minimize the impact of buffers on your weed control program by smart placement of technologies and sensitive crops. “We’ve really been stressing that farmers talk to their neighbors on the other side of that fencerow,” said Steckel. “I’ve talked to a number of growers who’ve called each other and adjusted what crop they’re going to plant based on what the other farmer was going to plant.
“Communication with your neighbors or getting eyes on what’s happening next door are very critical in knowing what is downwind. If for some reason you don’t talk with your neighbor regularly, drive over there and figure out what’s in that field. You can’t guess, you need to know,” Steckel emphasizes.
#7. Choose the right technology.
In some situations, a buffer may prevent a field from being sprayed at all. If you anticipate a no-spray situation at some point in the season, “then you need to plant a LibertyLink technology,” Scott says.
LibertyLink technology might also be a good choice in soybean fields with PPO-resistant Palmer pigweed. “You should not plant Xtend soybeans, because if you have to leave a buffer, there is no other herbicide option for you,” Scott specifies.