EDMONTON – Farm herbicides work just as well with five gallons of water per acre as the recommended 10 gallons per acre, according to a five-year study of sprayer technology.
“In 95 percent of the cases, we found the five gallons per acre at the full chemical rate was doing just as good a job and in some cases a better job,” said Brian Storozynsky, project manager with the Agtech Centre in Lethbridge.
While the study was designed to test the myriad of sprayers, spray nozzles and spray tips, it became apparent that water rate was often more important than sprayer technology, he said.
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“At five gallons per acre, our results are similar to 10 gallons per acre. It didn’t matter what sprayer or nozzle we were using, we got the same results,” Storozynsky told farmers at the FarmTech 2003 conference.
“Five gallons is working, there is no doubt about it.”
Most herbicide labels recommend a water rate of 10 gallons per acre. For some fungicides, the recommendation jumps to 20 or 40 gallons per acre.
But in five years of research that included 10 to 15 chemicals representing a range of herbicide groups, all the chemicals did just as well or better with the lower water rate, he said.
For farmers and custom sprayer operators, the half rate means thousands of dollars of savings in water and time hauling it to the field.
“At 10 gallons per acre, that’s hauling a lot of water,” he said.
“You’ve reduced your workload by 50 percent by going to five gallons an acre. Custom applicators would really be able to reduce their water. They could make a lot more money if they didn’t have to haul all that water. They’re hauling a lot of water for no reason.”
Custom applicators must follow the label rate to protect their liability in case something goes wrong during spraying.
However, Storozynsky said many custom applicators already reduce the label rate by using about seven gallons per acre.
Storozynsky said some companies in the past five years have changed their pesticide label application rates to five gallons of water per acre, but they aren’t going to retest old chemicals.
Now that Agtech is confident herbicides are as effective at five gallons of water per acre as the higher rate, they will test two and three gallons per acre, which some farmers are already using.
Storozynsky said most herbicides in the 1960s were designed to be sprayed with two and three gallons of water. In the 1970s a new nozzle was developed that had a lot of spray drift. The amount of water was increased to reduce the drift.
