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Farmers mixing more herbicide cocktails

For effectiveness and to reduce the risk of herbicide resistance more farmers are using herbicide blends against weeds

What’s your weed-of-choice these days? That answer seems to be a moving target not only across Western Canada but on individual farms. Farmers interviewed for the Farmer Panel say one weed seems to be a problem for a while — they get that dealt with and then other species come along to pose a challenge to crop yields.

Depending on the crop and where they farm, Panel members cited everything from cleavers, to wild oats, to Canada thistle, to kochia, to volunteer canola as their most problematic weeds. Solutions appear to be a combination of tools.

No one expects weeds to be completely controlled, but using a combination of herbicides, proper herbicide rotations, proper crop rotations, eliminating weed seed sources on field boundaries and improving soil quality to boost crop competition are among the tools producers are using to keep weeds manageable.

Here is what Farmer Panel members say are the top one or two problem weeds on their farms and how they manage them.

John Burns Kandahar, Sask.

Using effective herbicides, following a proper rotation and eliminating at least some of the seed source is the program John Burns follows to control cleavers on his farm in east-central Saskatchewan, about half way between Saskatoon and Yorkton.

Burns, who farms with family members, says cleavers are of particular concern in canola and flax. It is a weed that has been around his area for several years but it seems to have become more of an issue in recent years.

“At one time scentless chamomile was the big problem but over 20 years of farming you learn how to manage it,” says Burns “Scentless chamomile is a weed you can manage quite nicely under a direct seeding, zero till system, but not so with cleavers.”

A single cleavers plant, with a clinging vine, can produce up to 3,500 seeds. It is impossible to clean cleaver seed out of canola seed and the viney nature of the plant produces problems at harvest. “It produces a condition called hay stacking which is a problem when you are trying to straight cut the flax crop,” says Burns.

To reduce the cleavers numbers he follows at least a three- to four-year canola rotation with canola crops. Along with canola, about 15 per cent of the farm is seeded to winter wheat and he also grows dry yellow peas, oats, flax, malt barley and hard red spring wheat. With rolling topography on part of the farm, he’d like to find another pulse crop to include in rotation, hoping perhaps he can develop a market for faba beans.

Group 2 herbicides will control cleavers but he is concerned about weeds developing herbicide resistance with too many applications of products that use the same mode of action for weed control. Glyhphosate is quite effective in controlling the weed in canola. He’ll apply a pre-seeding burn down and then follow with two applications of glyphosate in-crop when growing Roundup Ready canola. Group 2 herbicides used with Clearfield canola are also effective, while Liberty Link herbicide used with Invigor canola is not as effective.

On fields ear-marked for flax he uses a fall application of Authority herbicide, usually followed by a spring application of Express herbicide. In-crop he uses Basagran to control weeds.

“We aim for a four year rotation with canola and then in the alternate crops we try to be as effective as we can in controlling cleavers so they aren’t as much a concern the next time we seed canola,” says Burns.

Burns has also been removing some of the tree and shrub shelterbelt rows on the farm as another weed control measure. “Cleavers, other weeds and even diseases can thrive in those tree rows,” he says. “You can apply good control measures in your field, but then 30 meters out from the tree rows the weeds will establish again. Today with zero till farming practices the risk of erosion is greatly reduced so removing the tree rows makes it easier to control the spread of weeds.

“Overall the two major tools we have is proper chemistry and applying good agronomic practices to optimize crop competition,” says Burns.

Eric Brewer Hamiota, Man.

A pre-harvest application of glyphosate for the past several years is helping Erle Brewer of Hamiota win the battle against Canada thistle and dandelion on his southwest Manitoba farm.

“There is always going to be some around, but it is a lot better than it was,” says Brewer, who has been using the pre-harvest treatment for the past eight years.

Brewer applies a full one-litre rate of glyphosate on all wheat acres in August. The treatment helps to dry down and even out the crop for straight combining and also knocks out the weeds.

With peas, he usually applies a Reglone treatment in August for crop dry down, and later if the weather co-operates he makes a post-harvest application of glyphosate on the pea acres to control any winter annuals. Cleavers can be a concern in canola, but he finds a two-time, in-crop application of glyphosate at the half-litre rate on Roundup Ready canola keeps the cleavers in check.

“I believe we are winning the battle,” says Brewer. “Weed numbers seem to get a little better (lower) every year. But you are always going to have some, particularly with the thistle and dandelion as weed seeds will blow in from the ditches. It is better than it was, but we just have to keep at it.”

Ryan Lecoq Agronomist, Artel FarmsNiverville, Man.

Wild oats and wild buckwheat are the two mains weeds on Ryan Lecoq’s radar each year as agronomist for Artel Farms at Niverville, in southern Manitoba, just south of Winnipeg.

A basic strategy is to apply a pre-seeding burn down with glyphosate and then follow up with effective in-crop treatments.

“Wild oats are a concern in pretty well every crop, but especially in the cereals,” says Lecoq, who operates n-Raje Agronomy from his home base at nearby St. Adolphe. “With wheat and oats, for example, we apply the pre-seeding burndown and then follow with an in-crop application of a Group 2 product such as Everest or Simplicity. It appears to be quite effective.”

Lecoq says he does see wild oats that develop resistance to Group 1 and Group 2 herbicides, but he finds it easier — has more options — for dealing with weeds with Group 2 resistance.

Wild buckwheat is the second biggest concern particularly in the Roundup Ready crops such as soybeans and corn.

“As long as you stay on top of them, you can keep them controlled,” he says. “Timing is important, so you need to treat them early, while the weeds are less than two inches tall.”

He says two in-crop applications of glyphosate to catch first and second flushes of the weed are usually quite effective.

“Glyphosate is very effective, but of course my one biggest concern is about glyphosate resistant weeds,” says Lecoq. “We don’t see it yet, but it’s just across the border (in the U.S.). We have to be watching for it. There are solutions for dealing with it, but it just depends on which weed shows up first.”

Josh FankhauserClarseholm, Alta.

Wild oats is the main weed to be concerned about on Josh Fankhauser’s family farm near Claresholm in southern Alberta, but of over all greater concern he is working on a strategy to reduce the risk of seeing development of glyphosate-resistant weeds.

“Glyphosate is such a valuable chemistry that we have to do what we can to reduce the risk of resistance,” says Fankhauser. “We were applying two litres of glyphosate on nearly every acre of the farm every year. So now my focus is minimize the risk and to do that I am doing all I can to reduce the amount of glyphosate we use.

“We are doing everything and anything, trying to be pro-active. We follow the most extended rotation we can, we’re going back to some of the old tried and true herbicides, we include more winter wheat in the rotation — the idea is just to keep changing things up so we keep the weeds guessing.”

Avadex is one of the “old” herbicides in Fankhauser’s tool box. “If the snow is gone I have even gone out in January and applied Avadex,” he says. “We use glyphosate for a pre-seeding burndown, but now we use more additives with other chemicals so there are two modes of action. And in the fall we use a combination of Dicamba and 2,4-D to control broadleafs and other winter annuals such as dandelion and thistle.”

Fankhauser also grows less Roundup Ready canola in favor of Liberty Link varieties.

An extended crop rotation with a wider range of crops also keeps “the weeds on their toes” and Fankhauser believes in long-range planning.

“I haven’t got this year’s crop seeded, but I already know what I am growing next year,” he says. “I have my crop rotation planned out for the next four years, and I also have my herbicide rotation planned for the next four years. Unless some new chemistry comes along, I already know what herbicide groups I will be using on what crops over the next four years. And I keep a white board in the shop too and there’s always lots of figuring going on there as well.”

Jason Craig Delburne, Alta.

Volunteer canola is probably the Number 1 weed on Jason Craig’s central Alberta farm. He grows mostly Liberty Link canola varieties and with a four-year rotation, he uses the three intervening years to control the volunteers.

“The volunteers can really be a problem if you don’t stay on top of them,” says Craig who farms at Delburne, east of Red Deer. His rotation usually follows canola/barley/wheat/peas. The first year after canola, he usually applies a combination of glyphosate and Express Pro to knock back volunteer canola and other weeds.

In the wheat year he’ll still see some volunteer canola, but probably just apply straight glyphosate as the pre-seeding burn down. And hopefully by the pea year the volunteers have disappeared.

Cleavers can also be a concern on his farm, but he finds that most in-crop herbicides are effective in providing control.

“I believe the key in controlling weeds is to follow a longer rotation, and I think it is also important to hit them early before they get much of a start,” he says. “Using a combination of products is also important. When we started into zero till farming about 10 years ago we used quite a few combination products to control weeds, that seemed to be effective and then we went more to straight glyphosate. Now the shift seems to be back to using more combination products so you are hitting the weeds with different products with different modes of action.”

Charles Schmidt Chinook, Alta.

Improving the productivity of the soil which in turns improves crop growth and a heavier crop canopy is one strategy Charles Schmidt uses in his overall weed control program on his east central Alberta farm.

With a fair amount of solonetzic/high sodium soils on his Chinook-area farm, east of Hanna he says soil quality can be quite variable. “You can be going along combining a 45 bushel wheat crop and then you come to a two acre patch where it drops to five bushels and you have mostly kochia.”

Schmidt is adding calcium sulphate to the fertilizer blend this year in hopes of counteracting the high sodium levels which in turn should improve crop growth. “Rather than just hammer the weeds we are trying to change the environment to benefit the crop,” he says. “If you can do a pre-seeding burn off and then see that crop canopy close in after, that is your best weed control measure.”

Schmidt follows a 60/40 crop/chemfallow rotation on his farm. On chemfallow land he’s using more combination products to control kochia, wild buckwheat, volunteer canola and other weeds.

“The first treatment might be a combination of glyphosate and 2,4-D and then we come back with glyphosate and Banvel or other tank mixes,” says Schmidt. “The wild buckwheat has sort of a waxy leaf so glyphosate isn’t as effective and you have to use something else.

“You can do a drive-by, 60 miles per hour check and all looks pretty good, but then you get out and walk or drive through the stubble and you see this gnarly mass of weeds at the three to four leaf stage and it is just ready to explode. So you have to hit it with something effective.”

On the cropped acres, he applies a pre-seeding burn off with a glyphosate combination product and usually finds most in-crop herbicides effective at controlling weeds.

A newer product he has been using with canola is Aim, supplied by Racketeer, the glyphosate bulk handling system offered by Rack Petroleum of Biggar, Sask. Aim is a Group 14 broadleaf herbicide intended for preplant burndown and pre-seed application that can be used with canola, pulses and cereals.

“It seems to do a good job,” says Schmidt. “It is safe to use with canola and seems to do a better job of controlling kochia and narrow leaved hawkesbeard. It gets the crop off to a good clean start.” †

About the author

Field Editor

Lee Hart

Lee Hart is editor of Cattleman’s Corner based in Calgary.

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