Efficacy of multiple Brassica biofumigation techniques in the suppression of non‐native and native grass seedling emergence and productivity

Abstract

AbstractNon‐native annual grasses are degrading rangelands in the western United States and of vital management importance. Novel management strategies are needed to extend current approaches. The aim of this study was to determine if biofumigation was a viable strategy to manage non‐native annual grasses (cheatgrass, Bromus tectorum and ventenata, Ventenata dubia). We tested the effect of Brassica juncea as ground seed meal, seed meal leachate, mustard straw, mustard straw leachate and cereal straw at increasing rates on the two non‐native species and two native perennial grasses (Idaho fescue, Festuca idahoensis and bluebunch wheatgrass, Pseudoroegneria spicata) in a growth chamber experiment. A solarization split treatment was applied using a clear cover to determine if solarization enhanced the biofumigant effect. We recorded the number of emergent seedlings after a 3‐week growth period, determined the effective dose 50%, and the above‐ and belowground biomass. Emergence was inhibited for all species using ground seed meal and seed meal leachate, with lower rates and higher consistency achieved with ground seed meal. Three species were inhibited using mustard straw leachate (not F. idahoensis). Mustard straw reduced emergence in all species but was not different from cereal straw. Solarization did not enhance the effects of the biofumigant for seed meal or mustard straw; conversely, emergence increased from the seed meal and mustard straw leachates under solarization. Responses in biomass varied across species and treatment. Biofumigation applied as ground seed meal may be a viable option for integrated weed management in rangelands, but field experimentation is necessary.