Variation in Response of Four Nightshades (Solanumspp.) to Herbicides

Abstract

In field experiments at Prosser, WA, black nightshade (Solanum nigrumL. # SOLNI), eastern black nightshade (S. ptycanthumDun. # SOLPT), American black nightshade (S. americanumMill. # SOLAM), hairy nightshade (S. sarrachoidesSendtner # SOLSA), and sometimes accessions within a species responded differentially to herbicides applied preplant incorporated, preemergence, or postemergence. Also, the response of the nightshades to some of the herbicides varied significantly between years. Generally, black nightshade was more tolerant of herbicides than were the other three species. An accession of black nightshade from England and an accession of eastern black nightshade from Minnesota were the most tolerant of herbicides of eight accessions evaluated. Of the 25 herbicides evaluated, preplant-incorporated applications of ethalfluralin [N-ethyl-N-(2-methyl-2-propenyl)-2,6-dinitro-4-(trifluoromethyl) benzenamine] and preemergence applications of alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide], chloramben (3-amino-2,5-dichlorobenzoic acid), lactofen [1′-(carboethoxy)ethyl 5-[2-chloro-4-(trifluoromethyl) phenoxy]-2-nitrobenzoate], and metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl] acetamide] controlled all species best. These herbicides reduced the oven-dry weights of both accessions of all four species of nightshades by 93% or more. Nightshades varied widely in their response to the thiocarbamates.