Integrating cropping systems with cultural techniques augments wild oat (Avena fatua) management in barley (Hordeum vulgare)

*OACC Note: this research is of value to organic farmers applying cultural weed control methods

K. N. Harker¹, J. T. O’Donovan¹, R. B. Irvine², T. K. Turkington¹ and G. W. Clayton³

Abstract
Wild oat causes more crop yield losses and accounts for more herbicide expenditures than any other weed species on the Canadian Prairies. A study was conducted from 2001 to 2005 at four Canadian Prairie locations to determine the influence of repeated cultural and herbicidal management practices on wild oat population density, biomass, and seed production, and on barley biomass and seed yield.

Short or tall cultivars of barley were combined with normal or double barley seeding rates in continuous barley or a barley-canola-barley-field pea rotation under three herbicide rate regimes. The same herbicide rate regime was applied to the same plots in all crops each year. In barley years, cultivar type and seeding rate were also repeated on the same plots year after year.

Optimal cultural practices (tall cultivars, double seeding rates, and crop rotation) reduced wild oat emergence, biomass and seed numbers, and increased barley biomass and seed yield, especially at low herbicide rates.

Wild oat seed numbers at the quarter herbicide rate were reduced by 91, 95, and 97% in 2001, 2003, and 2005, respectively, when tall barley cultivars at double seeding rates were rotated with canola and field peas (“high management”) compared to short barley cultivars at normal seeding rates continuously planted to barley (“low management”).

Combinations of favorable cultural practices interacted synergistically to reduce wild oat emergence, biomass and seed production, and to increase barley yield. For example, at the quarter rate herbicide, wild oat biomass was reduced two- to three-, six-to seven- or 19-fold when optimal single-, double-, or triple-treatments were combined, respectively.

Barley yield reductions after low management were somewhat compensated for by full herbicide rates. However, high management at low herbicide rates often led to greater barley yields than low management in higher herbicide rate regimes.


Source
Weed Science (2009) 57: 326-337


Author Locations and Affiliations
(1) Agriculture and Agri-Food Canada, Lacombe Research Centre, 6000 C & E Trail, Lacombe, AB T4L 1W1
(2) Agriculture and Agri-Food Canada, Brandon Research Centre, Box 1000A, R.R. 3, Brandon, MB R7A 5Y3, Canada
(3) Agriculture and Agri-Food Canada, Lethbridge Research Centre, Box 3000, Lethbridge, AB T1J 4B1, Canada


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Posted January 2009