Mechanisms of Weed Suppression in Cover Crop-based Production Systems

Abstract

<jats:p>Field and laboratory studies were conducted to investigate the mechanisms of weed suppression by cover crops. High-performance liquid chromatograph analysis and a seed germination bioassay demonstrated that rye (<jats:italic>Secale cereale</jats:italic> L.) can be leached of its allelochemicals, redried, and used as an inert control for separating physical suppression from other types of interference. In a field study, rye, crimson clover (<jats:italic>Trifolium incarnatum</jats:italic> L.), hairy vetch (<jats:italic>Vicia villosa</jats:italic> Roth.), barley (<jats:italic>Hordeum vulgare</jats:italic> L<jats:italic>.</jats:italic>), and a mixture of the four species suppressed the emergence of eastern black nightshade (<jats:italic>Solanum ptycanthum</jats:italic> Dun.). Crimson clover inhibited the emergence of eastern black nightshade beyond what could be attributed to physical suppression alone. The emergence of yellow foxtail [<jats:italic>Setaria glauca</jats:italic> (L.) Beauv.] was inhibited by rye and barley but not by the other cover crops or the cover crop mixture.</jats:p>

The influence of cover crop variety, termination timing and termination method on mulch, weed cover and soil nitrate in reduced-tillage organic systems

“…A weed management tool for organic reduced-tillage systems could be the conversion of cover crops grown over winter into mulch 7,8 . Cover crops can help outcompete and manage weeds 6,[8][9][10][11] through both physical and chemical mechanisms 12 , in some cases providing weed suppression comparable to that of herbicides 10,13 .…”

Managing Weeds in Potato Rotations Without Herbicides

“…Cover crops that have reportedly suppressed weeds through direct competition or release of allelopathic compounds during decomposition of residues include: rye (Secale cereale), oats (Avena sativa), barley, rapeseed, mustards (Brassica juncea, Sinapis alba, B. napus), sorghum-sudangrass hybrids, and buckwheat (Boydston and Hang 1995;Boydston and Vaughn 2002;Clark, 2007;Creamer et al 1996;Lanfranconi et al 1993;Ngouajio and Mannan 2005;Putnam and DeFrank 1983;Weston et al 1989). Mustard foliage (and seed) contain glucosinolate compounds that upon hydrolysis produce isothiocyanates, which act as natural bio-fumigants (Brown and Morra 1997).…”

Barley (Hordeum vulgare)-induced growth inhibition of algae: a review

“…The identification of allelochemicals, which range from phenolics to quinones within the Poaceae family of which barley is a member, has received a lot of attention in recent years (Creamer et al 1996;Moyer and Huang 1997;Ridge et al 1999;Sánchez-Moreiras et al 2004). Lignin, a key component of the stem and seed heads of plant material, is believed to be the main source of phenolic acids and quinones.…”