Black Alder Seedlings Demonstrate Tolerance to Preemergence Herbicides in Preliminary Trials1
Abstract Seven preemergence herbicides, atrazine, metolachlor, napropamide, oryzalin, oxadiazon, oxyfiuorfen, and simazine, were screened for phytotoxic effects on newly planted black alder seedlings. All treatments containing atrazine significantly reduced seedling survival, as did simazine treatments greater than 3.4 kg/ha. The simazine rate of 3.4 kg/ha, the napropamide rate of 26.9 kg/ha, and metolachlor rates greater than 3.4 kg/ha temporarily stunted seedling height growth early in the first growing season. Temporary stunting was also observed for the highest rates of the granular and emulsifiable concentrate formulations of oxyfluorfen, 9.0 and 4.5 kg/ha respectively. However, those treatments that temporarily stunted height growth had no significant effect on seedling survival. Excluding atrazine, all of the preemergence herbicides evaluated in this study could be safely applied to newly planted black alder seedlings with no significant mortality or growth inhibition, providing the rate guidelines previously mentioned are observed. North. J. Appl. For. 3:76-79, June 1986.