Every day you delay spring burndown, you can bet winter annuals and early perennials are gobbling up the moisture and nutrients meant for the crop. 
“An early pre-seed burndown, even weeks before planting, provides the highest yields,” says University of Saskatchewan, Department of Plant Sciences, Research Assistant, Ken Sapsford, in Saskatoon. “A high weed population in
spring can reduce yield potential before the crop is even planted.”
In a six-site year study of wheat performance under three burndown systems, options were compared for burndown and seeding in the first week of May, the last week in May, and burndown in the first week with seeding in the last week. The study focused on early spring annual weeds and concluded in 2007.
“Regardless of when we seeded, we ended up with similar yields – if we controlled the weeds early. But we got a yield reduction if we delayed weed control until late May,” Sapsford says. “Weeds growing in May suck out a lot of surface moisture and nutrients, so they’re not available to the crop.”
Moisture conditions in the study were good in relatively wet years. In dry conditions, Sapsford says the yield differences would have been greater.
More bang for the air seeding $$$
Traditional advice – seed early for the best yield – may need further clarification. “The benefit we think we get from early seeding may actually come from the weed control operation prior to seeding rather than from getting the seed in the ground earlier,” says Saskatchewan Agriculture’s Extension Weed Specialist Clark Brenzil.
Earlier burndown may reduce trouble with hard-to-control winter annual weeds like narrow-leaved hawk’s-beard and cleavers. Delaying burndown often requires more glyphosate or a second active ingredient.
Brenzil sees a relationship between deep roots and precision seeding. “A heavy population of tap-rooted perennials, like dandelions, can result in poor depth control and some obstruction issues for direct seeding,” he says. “Controlling these shortly before seeding may not make a lot of difference in depth control and draft on the implement, but a few weeks of decay before seeding will minimize the physical interference. Fall application allows even more time for decay.”
The best yield response occurs if dandelions are sprayed before the vast majority begin to flower.
If winter annual weeds are the only targets for an early burndown, it may be safe to seed just one day after spraying. However, Brenzil says to delay seeding at least three days if the targets include perennial weeds. “As long as conditions are ideal for glyphosate application (sunny and reasonably warm), three days will be adequate for the product to circulate through the plant and get down into the perennial root.”
Ultra clean
Producers, thinking fields are relatively weed-free, sometimes choose to seed early without a burndown. “That’s usually a mistake,” says Blair McClinton, executive manager, Saskatchewan Soil Conservation Association in Regina.
“Be very careful about deciding against a burndown,” says McClinton. “The earliest weeds can be very small and hard to see.
You may get away without one, assuming you don’t have winter annuals. Usually after May 1 on the Prairies, you can almost plan a burndown as a course of action on every field. Burndown becomes more important as the seeding date progresses in May.”
The last thing a grower wants to see is a flush of wild oats or green foxtail after burndown before the crop gets established. “Wild oats probably will take over if you have a reasonable infestation emerge two or three days ahead of the wheat,” McClinton says.
Extending control in an early burndown can help to prevent this situation. It’s also a good practice for anyone who has previously planted one of the glyphosate-tolerant crops, like canola or soybeans, in rotation.
“Extended glyphosate control improves the likelihood that you will have a relatively clean field at the time of crop emergence, assuming the residual products do not injure your crop rotation,” says McClinton. “Some of the products that extend the control of glyphosate come with varying levels of toxicity and residual. Growers should be aware of that.”
Ideally, fields should be as clean as possible prior to seeding the new crop. “We always say that whatever plant gets out of the ground first will win the competition. Anything you can do to get your crop ahead of weeds will work in your favor,” advises McClinton.
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Every day you delay spring burndown, you can bet winter annuals and early perennials are gobbling up the moisture and nutrients meant for the crop.
“An early pre-seed burndown, even weeks before planting, provides the highest yields,” says University of Saskatchewan, Department of Plant Sciences, Research Assistant, Ken Sapsford, in Saskatoon. “A high weed population in
spring can reduce yield potential before the crop is even planted.”
In a six-site year study of wheat performance under three burndown systems, options were compared for burndown and seeding in the first week of May, the last week in May, and burndown in the first week with seeding in the last week. The study focused on early spring annual weeds and concluded in 2007.
“Regardless of when we seeded, we ended up with similar yields – if we controlled the weeds early. But we got a yield reduction if we delayed weed control until late May,” Sapsford says. “Weeds growing in May suck out a lot of surface moisture and nutrients, so they’re not available to the crop.”
Moisture conditions in the study were good in relatively wet years. In dry conditions, Sapsford says the yield differences would have been greater.
More bang for the air seeding $$$
Traditional advice – seed early for the best yield – may need further clarification. “The benefit we think we get from early seeding may actually come from the weed control operation prior to seeding rather than from getting the seed in the ground earlier,” says Saskatchewan Agriculture’s Extension Weed Specialist Clark Brenzil.
Earlier burndown may reduce trouble with hard-to-control winter annual weeds like narrow-leaved hawk’s-beard and cleavers. Delaying burndown often requires more glyphosate or a second active ingredient.
Brenzil sees a relationship between deep roots and precision seeding. “A heavy population of tap-rooted perennials, like dandelions, can result in poor depth control and some obstruction issues for direct seeding,” he says. “Controlling these shortly before seeding may not make a lot of difference in depth control and draft on the implement, but a few weeks of decay before seeding will minimize the physical interference. Fall application allows even more time for decay.”
The best yield response occurs if dandelions are sprayed before the vast majority begin to flower.
If winter annual weeds are the only targets for an early burndown, it may be safe to seed just one day after spraying. However, Brenzil says to delay seeding at least three days if the targets include perennial weeds. “As long as conditions are ideal for glyphosate application (sunny and reasonably warm), three days will be adequate for the product to circulate through the plant and get down into the perennial root.”
Ultra clean
Producers, thinking fields are relatively weed-free, sometimes choose to seed early without a burndown. “That’s usually a mistake,” says Blair McClinton, executive manager, Saskatchewan Soil Conservation Association in Regina.
“Be very careful about deciding against a burndown,” says McClinton. “The earliest weeds can be very small and hard to see.
You may get away without one, assuming you don’t have winter annuals. Usually after May 1 on the Prairies, you can almost plan a burndown as a course of action on every field. Burndown becomes more important as the seeding date progresses in May.”
The last thing a grower wants to see is a flush of wild oats or green foxtail after burndown before the crop gets established. “Wild oats probably will take over if you have a reasonable infestation emerge two or three days ahead of the wheat,” McClinton says.
Extending control in an early burndown can help to prevent this situation. It’s also a good practice for anyone who has previously planted one of the glyphosate-tolerant crops, like canola or soybeans, in rotation.
“Extended glyphosate control improves the likelihood that you will have a relatively clean field at the time of crop emergence, assuming the residual products do not injure your crop rotation,” says McClinton. “Some of the products that extend the control of glyphosate come with varying levels of toxicity and residual. Growers should be aware of that.”
Ideally, fields should be as clean as possible prior to seeding the new crop. “We always say that whatever plant gets out of the ground first will win the competition. Anything you can do to get your crop ahead of weeds will work in your favor,” advises McClinton.
Write a comment
- Required fields are marked with *.