Competition and Control of Fall Panicum (Panicum Dichotomiflorum Michx.) in Soybeans (Glycine Max (L.) Merr.)

Abstract

Fall panicum (Panicum dichotomiflorum Michx.) has become oneof the most serious weed problems in row crops, particularly in corn(Zea mays L.) and soybeans (GLycine max (L.) Merr.), in the Northeastern U.S. in recent years. Its resistance to 2-chloro-4-(ethylamino)-6- (iscpropylamino)-s-triazine (atrazine) has led to extensive proliferation in corn. The objectives of this study were to determine the competitive effects of various fall panicum densities in soybeans and to identify the critical period during which the crop can grow in association with the grass without yields being adversely affected. Chemical control of fall panicum and other broad leaf weed species was investigated. A uniform stand of fall panicum was established in a soybean crop and allowed to grow in competition with the crop for predetermined intervals after the crop emergence. Weed-free bands of various widths were established in soybean rows. In another study, fall panicum plants were thinned in soybean plots to single rows alongside the soybeans at various equidistant spacings. Post-emergence chemical control of fall panicum by various rates of 2[4-(4-trifluoromenthyl-phenoxy) propanoate(HOE29152) and sodium 5-[2-chloro-4-(trifluoromenthyl)phenoxy]-2-nitrobenzoate.....