| Solanaceous weeds such as eastern black nightshade (Solanum ptycanthum ), hairy nightshade (Solanum sarrachoides), and horsenettle (Solanum carolinense) are serious weeds in tomato production in Michigan. Groundcherries, such as clammy groundcherry ( Physalis heterophylla) and smooth groundcherry (Physalis subglabrata) are usually less troublesome weeds in tomatoes. Studies were conducted in the field and greenhouse to determine nightshade and groundcherry response to herbicides. Germination studies were conducted in growth chambers to determine the influence of temperature on germination of nightshade and groundcherry populations collected in Michigan. Post-transplant application of S-metalochlor (1.8 kg/ha), and dimethenamid-P (1.09 kg/ha) and pre-transplant application of flumioxazin (0.05 kg/ha), and oxyfluorfen (0.28 kg/ha) in the field gave 95% control of eastern black nightshade with no tomato injury. Postemergence application of pyridate (1.01 kg/ha) gave 60% control of eastern black nightshade in field with no crop injury. There was variation in dose response of eastern black nightshade populations to sulfosulfuron, halosulfuron, and metribuzin in the greenhouse. There was variation in dose response of hairy nightshade populations to halosulfuron. Eastern black nightshade had a higher germination rate than horsenettle, hairy nightshade, smooth and clammy groundcherries at 28/20°C. An eastern black nightshade population from Oceana County germinated at a wider range of temperatures from 28/20°C to 15/10°C. |
