Eight accessions of weedy nightshades representing five species were evaluated for response to four herbicides applied preemergence in growth chamber studies and four herbicides applied postemergence in greenhouse studies. Species differed in susceptibility to all herbicides evaluated. The largest differences were found with postemergence applications of chlorsulfuron {2-chloro-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino]carbonyl]benzenesulfonamide}; hairy nightshade (Solanum sarrachoides Sendt. ♯ SOLSA) was relatively susceptible, but eastern black nightshade (S. ptycanthum Dun.) was very tolerant. S. ptycanthum, however, was one of the more susceptible species. It was always more susceptible than black nightshade (S. nigrum L. ♯ SOLNI) to all other herbicides evaluated.
