Adding a pre-emerge herbicide application with residual control to your glyphosate-tolerant or IP soybean crop buys you time and quite possibly helps maximize yield by keeping the crop clean early on.
Hitting the right timing is hard
Nailing the timing of a second, in-crop application of glyphosate in glyphosate-tolerant soybeans can be hard. It’s like putting all your eggs in one basket. If you miss the window for the second spray, you’ll more than likely miss out on yield too.
Protect yourself against bad weather
Weather can keep you out of the field. Getting locked out for 10 days or more during spray season can have a serious impact.
“In our trials in 2009 where we delayed the in-crop glyphosate application to the third or fourth trifoliate, which equated to 10 days, we were able to protect yield where we had a residual herbicide and lost yield where we didn’t have one,” says Mike Cowbrough, weed specialist with Ontario Ministry of Agriculture, Food and Rural Affairs. “A custom applicator looks at that and thinks that for the price of DuPont™ Guardian® as compared to a single application of glyphosate, I’m buying a little insurance if I’m not going to get there on time.”
Art Delanghe is a custom applicator based in Ridgetown, Ontario. He custom sprays as many as 10,000 acres a year.
“We’ve had really good luck with Guardian®,” he says. “You probably gain two to three weeks of weed control with the residual compared to just straight glyphosate. That’s pretty impressive.”
Delanghe says that with Guardian®, he doesn’t have weed pressure robbing yield early in the season. He has seen a lot of farmers who used straight glyphosate have to go back into the crop three times.
A residual herbicide can boost control of dandelions
In some specific situations – like to control dandelions in the spring – a residual herbicide can boost the effectiveness of glyphosate substantially. Cowbrough says they applied soybean herbicides on a yellow nutsedge patch with no crop competition at the Elora Research Station. They harvested the nutsedge tubers which are the only part of the plant that overwinters to produce new plants in the spring. “Where we applied Guardian®, we had an over 95 per cent reduction in nutsedge tubers,” he says. “We had over 451 tubers in a softball-size amount of soil. In the soil treated with Guardian® there were only 35 tubers.”
IP soybeans need to start clean
If you’re growing identity preserved soybeans, you know how important it is to start clean. In conventionally tilled soybeans, some farmers have had good results with one pass of Guardian® without a second pass. The typical no-till grower will have to go back with a second application. But even then, they’ll get much better control of perennial weeds.
Some growers also want to add in a second active ingredient to their glyphosate-tolerant soybeans to help guard against weed resistance and weed shifts. Guardian® brings that second active ingredient and also buys you some time to make an in-crop application, if necessary.