Wild oat (Avena fatua) and sterile oat (Avena sterilis) response to selected herbicides

An experiment was initiated in Morocco in 1992 to determine sterile oat seed longevity in soil at three burial depths at the Settat and Allal Tazi stations. Seed survival was determined 6, 12, 18, and 24 mo after burial. Sterile oat seed with 88% viability deteriorated rapidly during the first 6 mo with reduction to 31% viability at Allal Tazi and to 16% at Settat. Seed had greater viability when buried shallow than deep. However, the viable seed was less dormant when buried shallow instead of deep.; The influence of triallate formulation, rate, and time of application on sterile oat control was evaluated in 'Massira' wheat in Morocco. Triallate as liquid and granular formulations at 1.5 and 2 kg ai/ha reduced sterile oat by 90% or more when applied 2 wk before and at planting. Wheat yield components increased as a result of triallate treatment, and grain yield increased from 13 to 150%.; Two hundred forty-two Red River Valley (RRV) and 2000 USDA accessions of wild oat from the United States and bulk populations of sterile oat from Morocco were evaluated in greenhouse experiments for their response to triallate, imazamethabenz, and tralkoxydim.; Accessions of both Avena species were highly susceptible to triallate at 0.5 kg/ha. Some RRV accessions of wild oat were tolerant to two herbicides, but only accession 125 was tolerant to all three herbicides. Accessions 294 and 327 survived imazamethabenz at 5-fold and accessions 125 and 291 at 10-fold the greenhouse rate that controlled the susceptible accessions. Accession 125 was tolerant to tralkoxydim at 5-fold the greenhouse rate.; A laboratory experiment was conducted to determine the absorption and metabolism of triallate by triallate-susceptible and -resistant wild oat accessions. More {dollar}rmsp{lcub}14{rcub}C{dollar}-triallate was recovered from the shoot of the resistant than susceptible accession. However, {dollar}rmsp{lcub}14{rcub}C{dollar}-metabolite content in the shoot was much higher in the susceptible than in the resistant accession. Small amounts of {dollar}rmsp{lcub}14{rcub}C{dollar}-triallate and -metabolites were found in the roots of both accessions indicating minimal translocation of {dollar}rmsp{lcub}14{rcub}C{dollar}-triallate applied to the shoot. Susceptible accession tended to absorb more {dollar}rmsp{lcub}14{rcub}C{dollar}-triallate than resistant accession. Reduced conversion of triallate to metabolites in the resistant wild oat accession appeared to impart resistance.