The Spray to Swath Interval calculator is an internet tool that helps farmers figure out the pre-harvest interval after spraying a desiccant or a pesticide.
“The pre-harvest interval (PHI) … is the minimum number of days that must pass between that last application of product and when you cut the crop. That’s either straight-cutting or swathing,” said Greg Bartley, director of crop protection and crop quality with Pulse Canada.
A couple of years ago, the Canola Council of Canada introduced the online calculator to help growers make better decisions about desiccants and pesticides prior to harvest.
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The calculator is part of the Keep It Clean program, a grain industry initiative to ensure that exports of pulse, oilseed and cereal crops satisfy maximum residue levels.
“Our agricultural exports must meet the standards set by importing countries, including their tolerances for pesticide residues and traces of disease,” the Keep It Clean website says.
”These tolerances differ from market to market, and importing countries are using highly sensitive equipment to test for residues.”
If a desiccant is sprayed on a crop when the moisture content is too high, or the crop is combined too soon after spraying, there is a greater risk of unacceptable pesticide residues in the seed.
For growers, the Spray to Swath Interval calculator helps them avoid residues in a particular crop.
If a farmer is growing lentils, for instance, she can look through a list of desiccants and pre-harvest aids on the Spray to Swath Interval website. For every product, the calculator provides the required wait time before cutting.
“It’s an easy tool to make sure growers are aware of the pre-harvest interval and the differences between them,” Bartley said.
“If you think of a lot of the desiccant products… you are (at) two to four days, depending on the crop. If you compare that to pre-harvest glyphosate, now you are at seven days to pre-harvest interval.”
The tool also helps growers with decisions around insecticides, fungicides and herbicides. There may be an insecticide that requires a couple of weeks of wait time before harvest.
“That’s maybe where the tool is powerful. It could rule out those products… if you know you’re harvesting in two weeks,” Bartley said.
The Spray to Swath Interval calculator can be synchronized with a smartphone calendar, so growers receive a reminder about the pre-harvest interval.
The tool may be simple and powerful, but it may also be under-used.
“I think (pulse) growers appreciate the ease of the tool. We do get good feedback,” Bartley said “However… I think there’s an opportunity for more growers to use it.”
The calculator can be found at keepitclean.ca/phi/spraytoswath.
