Tips for spraying in wet conditions

1. Missing a window of opportunity (due to moisture or any other reason) with herbicides, fungicides or insecticides often results in greater yield losses because the pests will have had a chance to cause damage, or are tougher to control later. Research in western Canada has shown over and over that removing weeds earlier significantly increases yields.

2. Big new sprayers have more horsepower but they weigh 30,000 pounds dry and up to 40,000 pounds with a full tank. Ideally, you don’t want to go into a low spot with a full tank. So here’s a tip from a Saskatchewan grower: With GPS you know where you’ve been, so spray all the higher ground first, then go back to the lower spots when the sprayer tank is only a quarter full. This reduces the risk of getting stuck.

3. Keep your speed up, if possible. Slippery conditions slow a sprayer down, which results in lower spray pressure as rate controllers attempt to maintain a constant application volume. This can cause nozzles to perform poorly. With low-drift nozzles, higher pressure is important to get the pesticide to work properly.

4. An option is to apply by air where product registrations allow. Aircraft can cover large areas in a short time. Most aerial applicators have all-weather airstrips. And aerial applicators can produce droplet sizes that provide the right amount of coverage for the product and crop in question. For more on early-season aerial application of herbicides, read the next article.

Thanks to Tom Wolf, research scientist with AAFC in Saskatoon, for his help with this article.