BRANDON, Man. – Incorporating herbicides in a no-till field? Impossible!
Maybe not. Researchers and several farmers at a zero-till workshop held here last week say from experience it can be done. They have brought granular herbicides like Treflan, Rival, Edge, Avadex and Fortress back into their zero-till herbicide rotations with encouraging results.
Success depends on a number of factors including the time and rate of application, the soil type, weather conditions and the type of seeders and harrows used, they said.
With so many wild cards, they warned, farmers should experiment in their own particular environment.
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In conventional tillage, granular herbicides are usually incorporated twice to prevent herbicide from being lost to sun and air. But standing stubble on zero-till fields seems to protect the chemicals when applied to the surface and extra soil moisture helps it to be ‘naturally’ incorporated through absorption.
While Avadex has been recently granted a minimum-till label (see opposite page), none of the other herbicides are approved by Agriculture Canada to be used in this way.
North Dakota State University researcher Greg Endres said the U.S. Department of Agriculture has been experimenting with the herbicides on no-till fields since the mid-’80s.
In the past couple of years, his university has conducted more research on wheat and soybeans with new no-till equipment to prove the herbicides will work.
Endres has applied various rates of Treflan (trifluralin) and Sonalan (ethalfuralin) on plots measuring 4.5 m by 10.5 m (15 ft by 35 ft) in the late fall or early spring. The granules were either left on the surface or moved below the stubble with zero-till implements such as undercutters or rotary hoes.
Some of his results show:
- Treflan applied at five pounds per acre to wheat in mid-October and incorporated with a rotary hoe controlled 79-88 percent of foxtail, as effective as the 83-86 percent control in a conventionally-tilled control plot. Granules left on the surface provided slightly less control at 76 percent.
- There was a 10 percent improvement in yield by doubling application rates, but the increased yield did not balance the higher cost.
- When applied in November, only the higher rate provided a good level of control on fields with no incorporation.
More foxtail control
As an added benefit, Endres said the experiments with fall application provided more foxtail control than with spring application.
“I think that’s mainly due to having a wider window of opportunity for receiving moisture, which will help to disperse and activate the chemical,” he said.
“In the spring, we really need to rely on Mother Nature and hope that everything’s just right.”
David Rourke of the Ag-Quest research farm at Minto, Man., pulled together research from a number of studies. Over wide-ranging conditions, conventional incorporation of these herbicides provides a little more control than surface application, he said.
But he warned drier regions can face more problems with surface application.
In his experience, lower rates provide less control for wild oats, but Rourke noted soil types may affect this factor. And overdoing rates can reduce stand and residue.
He, too, has had better luck with fall application, but said spring application can work as long as it occurs at least 14 days before seeding.
“We’re about 20 years behind where we should be in the use of these products in zero till,” Rourke said.
