Fl. Young et al., Predicting winter wheat (Triticum aestivum) yield loss based on jointed goatgrass (Aegilops cylindrica) populations from the previous season, WEED TECH, 14(2), 2000, pp. 423-427
To manage jointed goatgrass (Aegilops cylindrical, growers need an action t
hreshold decision aid to assist them in deciding when to rotate to a spring
crop instead of growing winter wheat (Triticum aestivum). A study was cond
ucted in Washington from 1992 to 1995 to predict winter wheat yield loss ba
sed on a jointed goatgrass population in the previous year's winter wheat c
rop. To describe the relationship between jointed goatgrass density in year
I and the resulting winter wheat yield loss in year 2, data were fitted to
a rectangular hyperbolic model. First year jointed goatgrass densities in
winter wheat of 1 to 5 plants/m(2) led to a second year winter wheat yield
loss of 3 to 30%, Yield loss was greater in a dry year than in a normal to
wet year. To initiate an action threshold for jointed goatgrass successfull
y, growers need to incorporate data from this study with their knowledge of
yield potential, price dockage of the subsequent winter wheat crop, and pr
ofitability of alternative spring crop rotations.