Submitted to: Handbook of Sustainable Weed Management
Publication Type: Book / Chapter
Publication Acceptance Date: 2/1/2003
Publication Date: 2/1/2004
Citation: BOYDSTON, R.A., AL-KHATIB, K. UTILIZING BRASSICA COVER CROPS FOR WEED SUPPRESSION IN ANNUAL CROPPING SYSTEMS. CHAPTER IN HANDBOOK OF SUSTAINABLE WEED MANAGEMENT, ED. H.P. SINGH, D.R. BATISH, AND R.K. KOHLI. HAWORTH PRESS, BINGHAMTON, NY. (PLANNED EARLY 2004) 2004.
Interpretive Summary: Utilizing Brassica species in annual cropping systems as a weed management tool is reviewed and discussed. Pest suppression is often attributed to decomposition products, mainly isothiocyanates, released after soil incorporation of the Brassica cover crop. Isohthiocyanates are derived from hydrolysis of parent glucosinolates present in the plant tissue. The quantity and chemistry of hydrolysis products of glucosinolates depends upon plant part, plant age and environmental conditions. Various strategies of fall or spring planted Brassica species have been tested as components of integrated weed management systems. Brassica hirta and Brassica juncea are two species that growers have adopted in Pacific Northwest production systems.
Technical Abstract: The use of Brassica cover crops has increased recently as a result of benefits to growers such as weed, nematode, and disease suppression, soil conservation, nutrient cycling, and increasing soil quality. Brassica cover crops suppress weeds due to fast emergence and vigorous competitive growth during establishment and allelopathic substances released during degradation of the cover crop residues. The mechanisms of pest suppression with brassicas are not completely understood, but breakdown products of glucosinolates, such as isothiocyanates, are believed to be involved. White mustard (Brassica hirta), rapeseed (Brassica napus), brown mustard (Brassica juncea), and oilseed radish (Raphanus sativus) have been utilized as fall- or spring-planted cover crops with varying success. As a component of integrated weed management, utilizing Brassica cover crops in rotations could improve weed control and reduce reliance on herbicides.