Diversify Sites of Action

The most effective means of conserving herbicides is diversifying weed management programs by combining herbicides with different SOAs and incorporating nonchemical control tools. Diversification reduces direct selection pressure by reducing the number of applications of a single herbicide, especially the number of consecutive applications of a single SOA. Application of two different SOAs in sequence tends to conserve the efficacy of both, but particularly that of the first applied because the second application may control weeds that escaped the first because of the beginning stage of resistance.

Targeting the most troublesome and resistance-prone weeds within a field by using different herbicide SOAs in annual rotations, tank mixtures and sequential applications can delay the evolution of resistance by minimizing the selection pressure imposed on those weed populations by a particular herbicide SOA.

Lookup a Herbicide’s SOA