This is where birds are your friends. Birds think grubs are yummy.
I have never had to personally deal with grubs. And I have yet to encounter an organic grower that has had to deal with them. But I have had many people write to me and ask how to deal with grubs organically. Nearly all of them have mentioned "Last year I sprayed toxic goo to get rid of the grubs and now they're back". While I did not see what happened, my guess is that birds and other natural grub control ate the dead grubs and died. No more natural grub control.
So the trick is to kill the grubs, but don't harm anything that eats grubs. The answer is to bring in more grub predators.
Having done a little reading on this topic, "Milky Spore" (Bacillus popilliae) and/or predatory nematodes appear to be the organic control. "Milky Spore" is a naturally occuring bacteria that makes the grubs puke their guts out, but it doesn't seem to bother anything else. So if a bird eats a dead grub, the bird will be fat and happy. Predatory nematodes (also called "beneficial nematodes") are like micro worms that crawl through the soil and eat a variety of different organisms, including grubs.
Elfriede B wrote:
I am seriously thinking pigs.