Research was conducted to determine environmental and cultural factors influencing triallate phytotoxicity to hard red spring wheat. Triallate injured ‘Alex’ wheat more than ‘Coteau’ but injury was not influenced by triallate application date. Wild oat control was greater when triallate was applied immediately before seeding compared to 12 d before seeding. Triallate tolerance in wheat did not relate to solid stem characteristic. Injury was highest when wheat was seeded in a 4-cm incorporated triallate layer and least when wheat was seeded below the treated layer. However, triallate injury to wheat was similar at both seeding depths within the 8-cm incorporated triallate layer. Triallate at 1.1 kg ai ha-1 reduced wheat fresh weight approximately 33% with a soil at 8 C but over 84% with a soil at 24 C.

Imazamethabenz is a selective herbicide used to control wild oat in small grains. The effects of rate, volume of carrier, and surfactant concentration on the efficacy of this herbicide in controlling wild oat were studied in field experiments. As each of the variables increased, wild oat control increased; the greatest degree of wild oat growth inhibition occurred at the highest herbicide rate, highest volume of carrier, and highest surfactant concentration.

The control of wild oat, volunteer wheat, and volunteer barley in a flax crop with sethoxydim was enhanced 20 to 27% by orienting the spray nozzles forward 45°. Control of annual grasses was not influenced by the time of day sethoxydim was applied. However, injury to flax from a tank mixture of sethoxydim and bromoxynil/MCPA (1:1) was greatest when applied between 0500 and 1100 h, and least when applied between 1500 and 2300 h. Flax injury and reduced seed yields also resulted when sethoxydim was applied when air temperatures exceeded 30 C regardless of stage of crop growth.

Three grass selective herbicides, sethoxydim, fluazifop, and haloxyfop, applied to wild oat plants at the five-leaf stage inhibited growth and induced chlorosis in leaves. Young and actively growing tissues were affected first. Stem elongation in wild oat was inhibited within 2 days of treatment with sethoxydim and within 5 days of treatment with fluazifop or haloxyfop. At these same observation times, internodes that were elongating rapidly at the time of treatment were constricted at the base. These symptoms were followed by necrosis of the internode tissue. Histological examination of the affected internodes indicated that the herbicides inhibited cell division in very young internodes and inhibited both cell division and cell elongation in slightly older internodes. Initial injury occurred in the epidermal, cortical, and procambium cells of the peripheral regions of the stems located at the base of the affected internodes. Necrosis then progressed to the center of the stem tissue and all cells in the internodes were killed within 14 days of treatment. All three herbicides caused similar morphological and histological effects on developing wild oat stems.