Allelopathic potential of winter cereal cover crop mulches on grass weed suppression and sugarbeet development

Winter cereals are increasingly adopted for their use as cover crops in several cropping systems. This study was conducted to measure the effect of two barley (Hordeum vulgare L.) and six triticale (X Triticosecale) cultivars and three rye (Secale cereale L.) populations, used as cover crops, on the emergence and growth of barnyardgrass [Echinochloa crus-galli (L.) P. Beauv.], bristly foxtail [Setaria verticillata (L.) P. Beauv.], large crabgrass [Digitaria sanguinalis (L.) Scop.], and sugarbeet (Beta vulgaris subsp. vulgaris). Also, bioassay studies were conducted to assess allelopathic potential of the winter cereal extracts on large crabgrass and sugarbeet. Large crabgrass and sugarbeet growth were reduced more by rye extracts than by triticale or barley. In the field, barnyardgrass, bristly foxtail, and large crabgrass emergence in mulched plots was 39 to 69%, 0 to 34%, and 0 to 78% lower, respectively, as compared with that in mulch-free plots. Sugarbeet yield in no-herbicide and herbicide subplots mulched with barley or rye was greater than that of triticale or mulch-free subplots. In particular, sugar yield in no-herbicide subplots mulched with 'Athinaida' barley or rye from Albania were about 7 and 26% less, respectively, than those obtained in the respective herbicide-treated subplots. These results suggest that Athinaida barley and the rye from Albania could be used as cover crops for annual grass weed suppression in sugarbeet.