Harker: Integrated Crop Management Systems for Wild Oat Control
Date: April 2013
Term: 5 years
Status: Completed
Researcher(s): K.Neil Harker, John O’Donovan, Kelly Turkington, Vern Baron, Agriculture and Agri-Food Canada (AAFC), Lacombe AB, Robert Blackshaw, Newton Lupwayi and Elwin Smith, AAFC Lethbridge, AB, Eric Johnson, AAFC Scott SK, Denis Pageau, AAFC Normandin, QC, Linda Hall, University of Alberta, Chris Willenborg and Steve Shirtliffe, University of Saskatchewan, Rob Gulden, University of Manitoba, John Kobler, University of Guelph
SaskCanola Investment: n/a
Total Project Cost: n/a
Funding Partners: n/a
Project Summary
Wild oat continues to be the most economically important weed problem in Canada. Researchers conducted a study to determine if diverse rotation treatments combined with other cultural practices would reduce wild oat populations, and if diverse crop rotations would influence wild oat seed bank, soil microbes, and crop quality. Preliminary results from the study indicate that some diverse rotations in integrated systems without wild oat herbicides can be just as effective at managing wild oat as typical summer annual canola-wheat rotations in full herbicide-rate regimes. Final results will be available a few months after the 2015 growing season.
Wild oat continues to be the most economically important weed problem in Canada. Given the intense herbicide pressure, many wild oat populations are now resistant to several different herbicide modes of action. In fact, it is estimated that 37% of western Canada cropped land has a resistant weed species; over 75% of that land has a wild oat biotype resistant to herbicides. To slow herbicide resistance evolution, weed management techniques that include something other than herbicides are needed to preserve herbicide efficacy for when it is really needed.
Neil Harker with Agriculture and Agri-Food Canada (AAFC) in Lacombe, Alberta lead a five-year (2010 – 2014), no-till study at 8 sites across Canada (Lacombe, Lethbridge, and Edmonton, AB; Scott, and Saskatoon, SK; Winnipeg, MB; New Liskeard, ON; and Normandin, QC) to determine if diverse rotation treatments combined with other cultural practices would reduce wild oat populations, and determine if diverse crop rotations would influence wild oat seed bank, soil microbes, and crop quality.
The foundation for all successful integrated weed management programs is diverse rotations. Almost all wild oat research, even in integrated programs, has been conducted in summer annual crops. This project was designed to combine cultural weed management practices with minimal herbicide use to manage wild oat. Wild oat management was compared in diverse rotations that included winter cereals, chemical-fallow, and alfalfa with more common summer annual crop rotations (canola, wheat, barley, peas). In addition, diverse rotation treatments were combined with other cultural practices that reduce wild oat populations such as early-cut silage and higher than normal crop seeding rates.
In the trials, wild oat populations were established in canola in 2010. Natural wild oat populations were supplemented with seeded wild oats at each site to ensure adequate, uniform wild oat populations. Broadleaf weeds were treated with full herbicide rates.
Many of the crops were seeded at 2x the normal seeding rate. Wild oat density and biomass, crop density, yields and biomass were collected each year.
Diverse rotation treatments (including winter cereals, chemical-fallow, and alfalfa) were grown from 2011 to 2013 (See Table 1).
Table 1. Rotation treatments for the experiment. Some rotations were duplicated with varying crop seeding (1x or 2x) and/or herbicide rates (0%, 50% or 100%).
Figure 1. Selected individual plot photos at Lacombe in the Spring of 2013 (May 31). Note the canopy cover for perennial and winter annual (top) versus barley or spring wheat (bottom) crops at the time when wild oat is emerging. The former effectively preclude adequate light and other resource acquisition by emerging wild oat seedlings. Can, Alf, ES, WT, WW, and Wht = Canola, Alfalfa, Early-Cut Barley Silage, Winter Triticale, Winter Wheat, and Wheat, respectively. Seeding rate is either recommended or double (2x). Herbicide rates are 0, 50 or 100% (H). The large yellow numbers indicate spring wild oat emergence density averaged across four replications for the specific treatment.
Preliminary results from the study indicate that some diverse rotations in integrated systems without wild oat herbicides can be just as effective at managing wild oat as typical summer annual canola-wheat rotations in full herbicide-rate regimes. Given the fact that wild oat resistance to herbicides on the Canadian Prairies is increasing at a rapid pace, these results are very encouraging and important.
Figure 2. Wild oat emergence density at Lacombe in the Spring of 2013 (June 7). C, Alf, CFall, FR, ES, P, WT, WW, and Wht = Canola, Alfalfa, Chem Fallow, Fall Rye, Early-Cut Barley Silage, Pea, Winter Triticale, Winter Wheat, and Wheat, respectively. Seeding rate is either recommended or double (2x). Herbicide rates are 0, 50 or 100% (H). Blue bars are significantly greater than the bottom treatment (P < 0.05). Treatments with the orange box are those that received no wild oat herbicides for the last 3 years and yet have similar wild oat density as the 100% herbicide regime in the canola-wheat rotation (red box).
Experiments and data collection will be continued at all 8 sites through the 2014-growing season. Wild oat seed bank data (Fall 2014) and spring wild oat emergence data (Spring 2015) will help us determine if the successful treatments shown above can provide wild oat management in the absence of intense selection pressure for herbicide resistance. Some of these management ideas may then be available for growers for wild oat management that delays resistance to our most important wild oat herbicides. New knowledge generated from this research will provide growers with options to reduce herbicide expenditures, reduce selection pressure for weed resistance, and to grow canola in more sustainable rotations.
Full Report PDF: n/a