Effect of Soybean (Glycine max) Interference on Eastern Black Nightshade (Solanum ptycanthum)

Abstract

When grown without soybean [Glycine max(L.) Merr.] interference, eastern black nightshade (Solanum ptycanthumDun.) planted in May produced as many as 7000 berries and 800000 seeds per plant. Eastern black nightshade planted in mid-July produced as many as 100 berries, but those planted in mid-August failed to produce berries. Eastern black nightshade produced less than 85 berries per plant when planted with soybeans in May, 0 to 3 berries per plant when planted into soybeans in June, and no berries when planted into soybeans in July. However, when soybeans were defoliated in July to simulate hail injury, eastern black nightshade that had been planted with soybeans in May produced up to 1600 berries per plant, and those planted into the defoliated soybeans in July produced up to 58 berries per plant. We suggest, therefore, that in vigorously growing soybeans, control of eastern black nightshade emerging in the row would only be required through June to prevent berry production. If, however, the soybean canopy were disturbed by hail or other factors, eastern black nightshade seedlings emerging in late July or early August might produce berries by soybean harvest.