AGCO releases Crop Tour Field Report on boom height, carrier volume, and droplet size
AGCO, which carries brands such as Fendt, Massey Ferguson, Gleaner, and Challenger, has released the latest data from its Crop Tour Field Report.
The report shows that proper sprayer setup and well-timed application leads to the best weed control.
LibertyLink cotton in Georgia and soybeans in Illinois were tested on, to examine the effects of ground speed, sprayer nozzles, droplet size, carrier volume, and sprayer boom height.
Jason Lee, AGCO agronomist and farm solutions specialist, says the biggest takeaway from the soybean plots in Illinois was the importance of application timing for weed control efficacy. The plots initially didn’t have a lot of weeds, so the agronomists waited for more weeds to emerge, which allowed some waterhemp plants to get quite large.
“The problem with waiting for a full flush of weeds before spraying is that some weeds will get way too big and really hard to control,” Lee explains. “We should control weeds when they’re small: four inches or less in height.”
The second factor of herbicide application was speed. Speeds used in the study ranged from 5 to 15 miles per hour, with carrier volumes ranging from 10 to 20 gallons per acre. Sprayer nozzles were also evaluated — with droplets of various sizes created from medium to extremely coarse.
Darren Goebel, AGCO director of Global Agronomy and Farm Solutions, says that speed isn’t really a factor when rate and droplet size are correctly maintained.
“From what we saw, as long as we were using the appropriate nozzle to give us the correct droplet size for the speed we were running, we’d get the right coverage,” Goebel says. “We thought maybe there would be a bigger effect due to speed, but we really didn’t see any issues as long as we were doing everything else right.”
Speed may not be a changing factor, but when spraying contact herbicides such as Liberty, coverage is a key consideration, especially at lower carrier volumes. Based on what was observed in the Georgia cotton plots, Goebel recommends applying at least 15 gallons of carrier volume per acre, and using nozzles that produce a coarse droplet.
He adds, “if you’re going to use nozzles that produce larger droplets, you really should bump the water up some more to ensure you’re getting good coverage.”
The last application factor that was studied was boom height, and results showed that the coverage penalty for improper height can be severe. The AGCO team compared the coverage and weed control achieved with booms at 20 inches and 60 inches above the target.
“Booms often get set too high because applicators don’t want them to accidentally hit the ground. But if you’re spraying four to five feet from the target, you’re not going to get proper coverage, and you’ll also likely get more drift,” explains Goebel.
“Ideally, for 110-degree spray angles, your boom height above the target should equal your nozzle spacing. So, if your nozzles are 20 inches apart, your boom should be approximately 20 inches above the target. At 60 inches, we only achieved about 30 per cent control. The spray simply didn’t make it to the target due to a combination of drift, and evaporation.”