Weed management in organic cereals: Advances and opportunities

Cereals are among the most competitive of crops, but under organic management, weeds remain the foremost production problem. Understanding the ecology of both weeds and cereals is paramount to developing non-chemical strategies that limit yield loss due to weeds whilst suppressing weed growth and weed seed deposition. Key mechanisms for weed management include enhancing the cereal crops' competitive advantage through practices that (1) reduce weed density, e.g. through use of a 'false seedbed', and cultivation, possibly though the use of selective weed control with inter-row cultivation, and (2) increase interspecific competition, including increased seeding rates, precise fertilizer placement, and promoting quick canopy closure. The challenge is to find combinations of weed management tactics that simultaneously provide acceptable levels of weed control, reduce weed seed return to the seed bank, are economically advantageous, and can overcome variability in weather. Presently, the best options for in-season weed management in organic cereals are increasing the seeding rate or the comparatively less common use of inter-row cultivation for selective weed control. As cultivation technology improves, increasing accuracy and bringing down costs, this practice may become more widely adopted. Further research should focus on identifying practices that maximize net returns and weed suppression whilst being cognizant of potential interactions with other pests, organic production issues, and weed management tactics. These efforts should also provide insight to the efficacy of potential strategies in the larger context of the farming system as parameters including the size of the weed seed bank will dictate what practices are likely to be successful. © 2012 Springer Science & Business Media BV.