I agree with the companion planting, however that seems to work better the following year then it does at the time of the problem. We had cabbage worms and snails last year and found that if we surrounded our broc. and brussles with saw dust the snails would leave it alone. I guess they just cant get though the saw dust that well.
I don't use any chemicals in our garden, but we do plant marigolds and nasturtiums every year to help ward off the pest along with a few other things like. basil , fennel , dill and such....If you can't eat it all make friends with your neighbors and or enjoy all the compost you will have for years to come.
I honestly think that after a few cycles of companion planting it gets much easier. We are also finding we have less pest then another guy I know that lives down the road and uses 7 dust every spring.
We have hoverflys and he don't , we see twice as many Bees and hoverflys as he does. hoverfly's and bees are vital to our gardening. if you don't have them around get them by attracting them. They are your work force when you are not around.