Minimize off-target movement while spraying
Herbicide-resistant weeds in corn and soybeans threaten your bottom line. Fortunately, help is on the way. Soybeans that tolerate new formulations of 2,4-D, dicamba, and HPPD inhibitors should debut later this decade. Firms are also looking for a new row-crop herbicide action mode – something that hasn’t been developed since the 1980s.
However, these new products and increased use of older ones raise herbicide-contamination concerns. Off-target management by drift and volatilization is also a potential threat. If you grow row crops in areas where specialty crops (such as grapes and tomatoes) are grown, you need to be even more vigilant.
Here are four steps you can take to minimize drift potential and to avoid product contamination.
Monitor Wind Speed
“Keep in mind, when you’re making those applications, wind speed has a huge role in off-target movement,” says Greg Kruger, cropping system specialist at University of Nebraska-Lincoln. As wind speed doubles, off-target movement at 90 feet downwind increases 700%, says Kruger.
“There is no substitute for common sense. If the wind is blowing, droplets will move,” says Kruger.
Manage Boom Height
Doubling the boom height from 18 inches to 36 inches can boost off-target movement 90 feet downwind by 350%, says Kruger. “The higher the boom, the longer it takes for the droplets to reach the ground,” he says.
Kruger says you should monitor speed. As it increases, so does the boom height, generally. “As you go faster, boom height goes up, but so does drift potential,” he says.
Maintain Distance From Susceptible Vegetation
If downwind distance is doubled from 100 to 200 feet, just 20% as much drift exists at 200 feet as at 100 feet, Kruger says.
Control Droplet Size
You can’t control wind direction, neighbors, or wind speed, but you can control droplet size. “One of the easiest things you can do is to control the pressure,” Kruger says. By dropping the pressure to create larger droplets, you will significantly reduce drift potential.
It’s a Balancing Act
New nozzle designs are specifically built and engineered to reduce drift, says Bob Wolf, co-owner of Wolf Consulting and Research, Mahomet, Illinois. Reducing drift is a necessary part of an effective application, but there are trade-offs.
“When selecting a nozzle, consider both drift potential and the ability of the nozzle to provide proper coverage to control weeds or targeted pests,” says Wolf.
Selecting the right nozzle to provide proper coverage for optimal pest control while simultaneously minimizing spray drift with larger drops is a balancing act.
That’s your challenge: to find the proper droplet size.
“Nozzle selection has the greatest influence on particle size. The nozzle type you select is going to be the biggest way you can change the droplet size and drift potential,” says Kruger.
Nozzles that worked well with older chemistries won’t necessarily provide the same coverage with new chemistries.
“Most labels are going to have some sort of indication in terms of spray nozzles,” Kruger says.