WSU Tree Fruit Research & Extension Center

Organic & Integrated Tree Fruit Production

Wednesday, September 26, 2018

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Search results on 09/26/18

707. Beer, E. and R. Heitefuss. 1981. Determination of economic thresholds and economic injury levels for monocotyle and dicotyle weeds in winter wheat and winter barley. I.. Zeitschrift fur Pflanzenkran. und Pflanzenschultz, 87(2/3):65-85.
Determination of economic thresholds and economic injury levels for monocotyle and dicotyle weeds in winter wheat and winter barley: 1.The methods of calculating threshold values in relation to economical and biological-technical influences for the example winter wheat. The percentage yield loss does not only depend on the weed density, but also on the yield-forming factors. Using the calculated correlations between weed density and yield loss, two equations are presented, by means of which the economic threshold and the economic injury level as well as the presumed monetary return of the weed control measure minus the expense for the control measure can be calculated independent of different economical and biological-technical influence factors.

715. Beer, E. and R. Heitefuss. 1981. Determination of economic thresholds and economic injury levels for monocotyle and dicotyle weeds in winter wheat and winter barley. II.. Zeitschrift fur Pflanzenkran. und Planzenschultz, 88(6):321-336.
The economic threshold for a mixed population of Alopecurus myosuroides and dicotyledonous weeds in winter wheat at the control datein spring will be 9.7% weed coverage. The calculated thresholds represent no fixed values.

6845. Thomas, P.E.L. and P.J. Schwerzel. 1979. Weed competition in Rhodesian wheat.. Rhodesia Agric. J. 76(2):73.
Competition for more than thirty days significantly reduced grain yields in one season when frost damage occurred. In the other three seasons weed competition for the first 42, 102, or 72 days had little effect on yield. When the weeds were competing for the whole season (+/- 150 days) grain yields were significantly lower in three seasons.

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