prevent the germination
of seeds by inhibiting a key enzyme
In some areas of the world, preemergent herbicides are used to prevent crabgrass from appearing in summer lawns.
2 brands of pre-emergent herbicide
- Pendulum, used for control of crabgrass in turf. Its active ingredient is pendimethalin.
- Surflan, used for control of crabgrass in turf. Its active ingredient is oryzalin.
Preemergent herbicides must be applied at a critical time. If they are applied to the soil too early they get washed too deep into the soil by rainwater. If they are applied too late the key enzyme inhibited is no longer active.
Depending on where you live, one rule of thumb is to apply when the local forsythia blooms are wilting.