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Ontario Grain Farmer Magazine is the flagship publication of Grain Farmers of Ontario and a source of information for our province’s grain farmers. 

The art of spraying


CONSISTENT WEED CONTROL is top of mind for many growers at this time of year. New technology to improve fertilizer and crop protection application continues to become available and as options grow, so does the need for purchase and practice recommendations.


Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) weed specialist Mike Cowbrough says growers are always looking for mixing, application, and equipment advice to help meet their weed control goals.

“It all starts in the tank but sometimes what we think is an herbicide tank mix compatibility issue is really a cleaning issue,” says Cowbrough. He says some products foam very easily, such as glyphosate. By adding a de-foaming agent, cleaning the tank can be made easier and gooey gel mixtures at next use can be avoided.

Steve Johns, sales manager at Syngenta Canada, says he commonly receives phone calls regarding tank mixes causing gelling and difficult clean out. “As a general rule, wettables, powders, and granulars agitate liquids, flowables, emulsifiable concentrates, and solutions in that order.”

“We all have our own experiences with our machines but if you are going to try a mix you have not done before, ask the retailer if there are any tricks you should know in terms of mixing order.”

Johns says a common mistake he sees is when growers are in a hurry and try to dump dry flowables into the tank instead of putting them through the inductor. “Always choke them through because inductors are the most efficient,” he recommends.

With regards to water quality, Cowbrough says research at Purdue University found that extreme pH values can reduce the solubility of some herbicides by preventing the product from dissolving. He says it is worthwhile to use litmus paper to test pH to confirm that water quality is not negatively impacting results.

“According to recent weed surveys, two species that were not on the radar 10 years ago are now coming in at the top of the chart – Canada fleabane and giant ragweed,” says Cowbrough. In addition, he says he is receiving a growing number of performance inquires about Lamb’s quarters.

“The first step to solving these issues is to look at product cover,” says Johns. “It is really important to know how the chemistry works so I encourage growers to think about the product being sprayed and develop an understanding of water volumes and droplet quality.”

When it comes to ragweed and Lamb’s quarters, he says most often there is not enough water being used and weeds are not getting enough droplets. “Chemicals are expensive so growers should be making them work as well as they can,” says Johns. “My advice is to not skimp on water or droplet quality.”

Cowbrough also reminds growers that size matters. “As Lamb’s quarters get taller, visual control subsides. Taller weeds have more Calcium in their leaves and are more difficult to kill.”

“Letting weeds get too tall is costing money in terms of yield potential. It just makes sense to control them early. If your crop is not Roundup Ready, the sweet spot is 21 to 23 days after planting,” says Johns.

Jason Deveau, OMAFRA’s application technology specialist, focuses his work on the equipment side of spraying and says there are a growing number of advancements available.

He lists working to reduce pesticide wastage and off-target contamination, developing methods to spray crops consistently, and developing educational resources for operators as three aspects of his mission.

“Two of the most attainable and cost effective tools I recommend are oil and water sensitive papers and nozzle calibration systems,” says Deveau.

Oil and water sensitive papers – a tool used to test coverage, drift, and contamination – are yellow cards that turn blue when sprayed. Deveau says these papers are a resource that few growers have tried but he recommends a package be kept in every cab and used regularly.

Innoquest Inc.’s SpotOn® Sprayer Calibrator is an example of Deveau’s recommendation of a nozzle system. “These tools are like vessels with two sensors inside. They can be held under a nozzle and within ten seconds will tell an operator exactly how many litres, ounces, or gallons per minute the nozzle is emitting,” he says, noting that ATI Agritronics Inc. offers a similar system called AppliMax Spray Nozzle Calibrator.

“There are many innovations that are newly available or becoming available that focus on air from K-B Agri-Tech LLC’s Pattern Master brushes that cut apparent wind speed, to Harrie Hoeben’s Wings sprayer from Europe which physically opens the canopy,” he says. “Air-assist booms work and I would like to see more of these in the fields this spring.”

Deveau regularly publishes new product information and educational course offerings on his website. His updates as well as free presentation downloads are available at or by following him on Twitter @Spray_guy. •


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