Synergy between Synthetic and Microbial Herbicides for Weed Control

Synthetic herbicides have been investigated as tools to synergize mycoherbicides (fungal bioherbicides) for improved efficacy or management of hard-to-control weed problems. Herbicides may weaken weeds and impair their defence systems, thus making weeds more vulnerable to mycoherbicide infection. Despite many positive results, the practical value of synergy remains elusive. This review will discuss several fundamental aspects of synergy relating to development of this technology based on author’s own experiences in biocontrol of green foxtail and scentless chamomile. These include application timing, dose effect, weed growth stage, and spray retention efficiency. Issues relating to the practicality, non-target risks, and cost of weed control are stumbling blocks to the adoption of synergistic technologies, and some tactics are proposed to address these challenges. _____________________________________________________________________________________________________________