Wild oat (Avena fatua) seed production in spring barley (Hordeum vulgare) is affected by the interaction of wild oat density and herbicide rate

Abstract

The efficacy of current wild oat herbicides and their high cost have resulted in use rates that are less than those recommended. While acceptable weed control may be attained at less cost, this practice does not consider the potential for increased wild oat seed production. The objective of this experiment was to determine the interaction of wild oat density and reduced imazamethabenz rates on wild oat seed production in spring barley. As wild oat densities increased from 8 to 1,100 plants m−2, wild oat seed production increased from 180 to 9,950 seed m−2without herbicide, and from 0 to 2,810 seed m−2using 0.53 kg ai ha−1imazamethabenz. This general pattern was modeled using a cumulative logistic function. Estimates from this model indicated that < 1 wild oat seed m−2was produced at population densities of ≤ 20 plants at any imazamethabenz rate. Imazamethabenz rates of 0.26 kg ha−1or greater at wild oat densities of less than approximately 190 plants m−2did not result in wild oat seed production above the initial population density. As wild oat density increased, however, imazamethabenz rates below 0.40 kg ha−1resulted in substantially greater wild oat seed production compared to the recommended rate.