To begin with various herbicides are available – choose one that targets the specific weeds on your land, and make sure you apply the correct dose.
French beans-After planting (3 days later) use pre- emergency herbicides such as Dual Gold to prevent the weeds from emergency.At a later stage you can use Bean clean for weeding
Cabbages -Use a selective herbicides such as Fusilade Forte.
NB Its important to consider the weeds you are controlling.