ARS | Publication request: BRASSICA GREEN MANURE CROPS SUPPRESS WEEDS

Submitted to: Weed Science Society of America Meeting Abstracts
Publication Type: Proceedings
Publication Acceptance Date: October 1, 1993
Publication Date: N/A

Interpretive Summary: Weed control in potatoes is highly dependent upon herbicide inputs or timely cultivation. Brassica species contain compounds which are hydrolyzed to isothiocyanates when the plants are decomposing in the soil. Isothiocyanates are know to inhibit seed germination and plant growth. In these studies, residues of two Brassica species, white mustard and rapeseed, were added to soil and inhibited emergence and growth of several common weed species. In two field studies, a fall- planted green manure crop of rapeseed reduced weed biomass in potatoes. Using Brassica species as green manure crops to suppress weeds and other pests in potatoes may reduce pesticide inputs in potatoes.

Technical Abstract: White mustard (Brassica hirta) and rapeseed (Brassica napus) were tested for use as green manure crops to suppress weeds. White mustard or rapeseed tissue mixed at 20 g fresh weight per 400 g dry sandy soil reduced emergence of five weed species and six weed species, respectively, in greenhouse trials. Reduction in weed biomass by adding rapeseed and white mustard was not consistent among soil types, locations, and weed species. Covering the soil with plastic wrap soon after adding Brassica residues to the soil improved weed control. In field studies, a green manure crop of rapeseed reduced weed biomass in potatoes by 90% in 1992 and 50% in 1993.