Tom Peters is by no means a clone of Michael J. Fox (aka Marty McFly). But he does have a "Back to the Future" focus right now that he hopes will be bought into by increasing numbers of Upper Midwest sugarbeet growers. Peters, Fargo-based extension agronomist-sugarbeet and weed science for North Dakota State University and the University of Minnesota, is hoping to bolster weed control in sugarbeets by taking a system-wide approach to the issue. In other words, he believes that in these days of increasing resistance to glyphosate and certain other herbicides, producers can take a big step toward satisfactory weed control in their beet fields by reviewing and modifying their weed management programs in other rotational crops, such as corn, soybeans and small grains.
That’s hardly a new concept, Peters knows. Indeed, it was an important component in the success of the microrate program conceived by Peters’ wellknown predecessor and mentor, Alan Dexter, in the 1990s. But it’s an approach that receded in the minds of many sugarbeet growers after 2008 — the first year that Roundup Ready® sugarbeets were produced commercially in most U.S. sugarbeet regions. The use of pre-emergent herbicides and other previously popular "post" products declined sharply as producers quickly embraced the simplicity and benefits of a glyphosate-based weed management program. It’s not quite that simple anymore for many growers, of course, given the glyphosate resistance (Peters prefers the term "weeds management") issues that have arisen — from waterhemp in southern Minnesota to horseweed in Michigan and kochia in several western beet states. Numerous producers have already jumped back into the use of pre’s along with other post herbicides to assist with tough weeds in their beet fields, and others are taking a hard look at doing so. That by no means indicates the Roundup Ready system is in retreat; simply that weed scientists and growers in a number of areas realize it needs supplementation. "In many cases, other rotation crops offer the farmer the advantage of using a unique brand of herbicides or herbicides that are not used in sugarbeet," Peters points out. "My thought is to use that to our advantage — to use that diversity of herbicides as a way of reducing the spread of resistant weeds." Peters began to actively address this "Back to the Future" approach in 2014, establishing research sites at Herman, Minn., and Barney, N.D., in the southern Red River Valley. The objective was to achieve optimum control of waterhemp (Herman) and kochia (Barney) in corn and soybeans by utilizing a systems approach based on five premises: (1) It is not reliant upon Roundup Ready technology. (2) It provides greater than 90% visual control of waterhemp and kochia on a season-long basis. (3) It utilizes herbicides from families grouped by modes of action that complement herbicides used in other crops within the cropping sequence, including sugarbeet. (4) It employs herbicides with appropriate rotation restrictions, thus allowing corn, soybean and sugarbeet to be planted within the same sequence. (5) It considers per-acre weed control costs, including the cost of the seed — i.e., profitability. A full listing of the corn and soybean herbicides evaluated at the two sites in 2014 can be seen in a report by Peters being posted at www.sbreb.org (the website of the Sugarbeet Research and Education Board of North Dakota and Minnesota). Below are several highlights of what transpired last season at Herman and Barney. Within the range of herbicides evaluated were preemergent, postemergent, and pre + post products. In addition to efficacy, treatments were selected based on herbicide site of action and chemical family, as well as crop rotation restrictions — and cost. The corn planted at both locations was a Roundup Ready hybrid; the soybean was a Liberty Link® variety.
Weed Control in Corn -- A number of herbicide treatments provided between 90 to 100% control of green foxtail, waterhemp, lambsquarters and redroot pigweed at canopy closure in the corn. Herbicide treatments applied post-emergence and containing atrazine, Laudis or Status provided broad-spectrum weed control at both locations. However, the Barney site, which had a very heavy infestation of kochia in 2013, had a very light kochia infestation — but heavy lambsquarters and redroot pigweed infestations — in 2014. "This emphasizes the importance of scouting and identifying weeds in fields and matching the observed weeds with the appropriate herbicide — especially in the case of post herbicides," Peters observes. Cost per acre for herbicide treatments ranged from $13 (two post applications of PowerMax) to $65 (two post applications of Widematch + Status + PowerMax). Weed Control in Soybean -- Visual assessment of soybean growth reduction and weed control in soybean was conducted at various times during the growing season. In general, the yield impact from insufficient weed control tended to mask any effect from phytotoxic effects of herbicide.Herbicide treatments provided broad-spectrum waterhemp, lambsquarters and redroot pigweed control. Control generally was best from soil-applied herbicides following post herbicide treatments. Post-only treatments tended to be less consistent and did not provide broad-spectrum control.As with corn, the soybean herbicide treatments were selected based on herbicide site of action and chemical family, crop rotation restrictions and cost. There are not as many herbicide choices in soybean, compared to corn, that allow rotation to sugarbeet the following season. But, Peters notes, "the soybean herbicides used in these trials generally have no rotational impact on crops grown in the rotation, including corn or sugarbeet."The per-acre cost of weed control in soybean ranged from $16 (two post treatments of Cadet) to $69 (a pre and post combination of Dual Magnum + Valor / Liberty). Peters and his colleagues plan to continue the research project for two to three more years. They’ll also be incorporating wheat into the sequence in 2015, recognizing that wheat is part of many Red River Valley rotations that include sugarbeet. What kinds of feedback has the NDSU/UM sugarbeet weed specialist received thus far from growers on this project — his "Back to the Future" reemphasis on system-wide weed management? Cost obviously is a major consideration — especially in a year like 2015 when commodity prices in general are down significantly. Peters is fully aware of that, but simultaneously stresses that a systems approach inherently factors in multiple years — in terms of both outlay and results. "A farmer has to be committed to spending more money if he wants to successfully implement this ‘weeds management’ approach," he states. "For the grower who is thinking long term, that makes a lot of sense. Where we ‘get into trouble’ a bit is on rented ground and situations like that where we’re really taking only a year-to-year approach. That’s where it breaks down somewhat — at least on the economics side."
'Zero tolerance should be our target, and we need to use all available means to achieve it.’
How does he answer the formidable economics question? "My answer is, ‘You are the farmer. You know what your budget is. You know your cost of production and what you need to plan for,’ " Peters states. "I’m saying you may have to consider a little more money for herbicides in your plan and find other places where you can save some money." Not everyone he’s talked with this winter is on board with his thinking, Peters admits. "Some are saying, ‘Yeah, it’s a great idea — but give me another year or two of the system I’m already using: the Roundup system. Maybe the economics will turn around by then.’ "Others, though — usually those having tough weed problems — are saying, ‘I have to do something, because what I’m doing now is not working, and I can’t afford to let it get worse.’ " The university weed scientist knows how difficult it is to achieve 100% weed control in any crop in a given year; but, he believes, that should be the objective for sugarbeet producers. "I think the ‘zero tolerance’ threshold concept — which, again, is not a new concept — is geared at there being no threshold in sugarbeets other than complete weed control. That should be our target, and we need to use all available means to achieve it." A key reason for setting the goal so high, Peters says, is the weed seed bank. "The problem with a weed like waterhemp is, if you have a failure, you’re going to have that seed in the seed bank for a good four years — maybe closer to six. That’s the first problem. "The second problem is that a single one of those escaped plants makes a tremendous amount of seed — more than 150,000. So you just can’t afford to have any of them going to seed. If you do, you’ll have to work even harder in the succeeding crops to clean it up." — Don Lilleboe
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