Competition of Wild Oats (Avena Fatua L.) in Wheat and Flax*

Abstract

Summary. This project was designed to study various aspects of wild oat competition in spring wheat and flax. From ten to forty wild oat plants/yd2 were sufficient to cause significant yield reductions in wheat when grown on summerfallow land or when ammonium phosphate fertilizer was added to stubble land. However, when wheat was grown on stubble land without the benefit of a fertilizer treatment, seventy to one hundred wild oat plants/yd2 were needed to suppress wheat yields significantly. This would suggest that on stubble land, soil fertility was a more important factor than moderate densities of wild oats in determining eventual crop yields. In these experiments, wild oats reduced the number of tillers per plant, but did not significantly affect the protein content of the harvested grain. Only ten wild oat plants/yd2 were sufficient to reduce flax yields significantly on both summerfallow and stubble land. The only exception was in 1966, when flax grown on summerfallow land was not significantly affected until the density of wild oats reached forty plants/yd2. This confirms the general observation that flax is a poor competitor with wild oats. The results suggest that wild oat competition had already commenced prior to emergence of wheat, particularly with the higher densities of wild oats. In general, competitive effects increased with time and with wild oat density. In flax, severe competition had already taken place prior to the 2–3‐Ieaf stage of the weed in 1964, but did not become severe until after the 2–3‐leaf stage of wild oat growth in 1965 and 1966. Again, competitive effects increased with time and with wild oat density. Results of a final series of experiments, suggested that the optimum seeding date for flax in Manitoba is the latter part of May or the first week of June. Yield reductions due to wild oat competition became very severe as seeding dates were delayed. La compétition de la folle avoine (A vena fatua L.) avec le blé et le lin

An Index of Competition for Estimating Crop Loss Due to Weeds

“…The following regression equations and corresponding correlation coefficients between y (observed yield) and f (predicted Bell and Nalewaja (1968a, b) and Bowden and Friesen (1967) The data used for estimating these equations are shown graphically in Fig. 1 Bowden and Friesen (1967).…”

“…The average weed count was 270 per square meter with yield reductions ranging from zero to 6l%. Alex (1968), Bell andNalewaja (1968a, b), Bowden and Friesen (1967), Burrows and Olson (1955), Gruenhagen and Nalewaja (1969) Can. J. Plmt Sci.…”

“…J. Plmt Sci. 52.jl2l-927 (Nov. 1972) (Bell and Nalewaia 1968b) and for flax at Carrington in 1965 (Bell and Nalewaja L968a) were used, as was the mean of 3 years wheat on fallow at Winnipeg (Bowden and Friesen 1967). These data were combined and plotted ( Fig.…”

Effects of Volunteer Wheat and Barley on the Growth and Yield of Flax

“…Bowden and Friesen (1967) reported average flax yield reductions of 24 and 50% from l2 and 48 wild oat plants m-2.…”

Comportamiento de la poblacion de Avena fatua tratada con graminicidas postemergentes

“…Posee diversas estrategias de supervivencia y perpetuación, lo que la caracteriza como una especie difícil de controlar. Se encuentra ampliamente difundida en los cultivos de trigo y otros cereales en varios paises del mundo causando en éstos severas pérdidas de rendimiento por competencia y disminuición del valor comercial del producto cosechado (Bowden & Friesen, 1967;Bell & Nalejawa, 1968;Chancellor et al, 1976;McNamara, 1976;García Baudín, 1982;Wilson & Peters, 1982;López, 1983;O'Donovan & Sharma, 1983).…”