The best way to avoid dicamba drift is to follow label directions.
Although dicamba can be applied to Xtend soybeans from pre-emergence to early flowering, applying pre-emergence has advantages. One is if your crop isn’t up your neighbour’s might not be either and can’t be damaged by drift.
“Dicamba provides residual control for a short period of time,” Terry Buss, a pulse crop extension specialist with Manitoba Agriculture, said during the Crop Diagnostics School in Carman in July.
Research shows earlier weed control boosts crop yields.
Monsanto also recommends applying dicamba with nozzles that produce coarse, to ultra-coarse, droplets such as Turbo TeeJet Induction and Air Induction. Those nozzles require application rates of at least 10 gallons of water an acre.
Spraying should take place when wind speeds are three to 15 kilometres an hour and at sprayer travel speeds of no more than 24 kilometres an hour. Boom height should be no more than 50 centimetres, Monsanto says.
Farmers shouldn’t spray during inversions or when wind conditions are dead calm, Buss said. The spray might not penetrate the crop canopy and could move to a neighbouring field.
“There is potential for a lot of drift damage if we are not doing things properly,” he said.
Farmers and their employees should also pay more attention to what they and their neighbours are growing to avoid not only drift, but spraying the wrong field, Buss said.
Also be aware of recropping intervals. Manitoba’s Guide to Field Crop Protection 2017 says after applying one litre of Monsanto’s dicamba (called XtendiMax with VaporGrip Technology) per acre, farmers should grow only cereals, corn, soybeans or white beans the year after.
After applying a half-litre per acre, only grow cereals, corn, soybeans, white beans or canola the next year.
“If applications are made after Sept. 1, or if dry weather persists after application, crop injury may occur the following spring,” the guide states. Cleaning all the dicamba out of a spray tank isn’t hard, but critical.
“Eight ounces of dicamba solution — not the concentrated product, but the solution left in a big sprayer filled up with something else — can cause (injury) symptoms,” Buss said. “If you leave three gallons of solution in that sprayer… and then fill up and go spray something else susceptible you can actually cause yield loss.”
Monsanto’s XtendiMax with VaporGrip Technology label calls for cleaning sprayers immediately after application and using a triple-rinse procedure as follows:
- After spraying immediately drain the sprayer, including boom and lines. Do not allow the spray solution to remain in the spray boom lines overnight prior to flushing.
- Flush tank, hoses, boom and nozzles with clean water.
- Inspect and clean all strainers, screens and filters.
- Prepare a cleaning solution with a commercial detergent or sprayer cleaner or ammonia according to the manufacturer’s directions.
- Take care to wash all parts of the tank, including the inside top surface. Start agitation in the sprayer and thoroughly recirculate the cleaning solution for at least 15 minutes. All visible deposits must be removed from the spraying system.
- Flush hoses, spray lines and nozzles for at least one minute with the cleaning solution.
- Repeat above steps two additional times to accomplish an effective triple rinse.
- Remove nozzles, screens and strainers and clean separately in the cleaning solution after completing the above procedures.
- Appropriately dispose of rinsate from steps one to seven in compliance with all applicable laws and regulations.
- Drain sump, filter and lines.
- Rinse the complete spraying system with clean water.
All rinse water must be disposed of in compliance with municipal, provincial, and federal guidelines.