Mother Earth News (No. 246) put out the results of what works/doesn't for readers across the states. I won't give the full details but here are a few:
Slugs:handpicking, iron phosphate baits, and DE Squash Bugs: handpicking, cleaning up infested plants at seasons end Aphids: pruning off infected parts, insecticidal soap, attracting beneficials Imported cabbageworms: Bt, spinosad, paperwasps Squash vine borers: crop rotation, growing resistant varieties of Curcurbita moschata (solid stems) Japanese Beetles: handpicking, growing trap crops of raspberries or other fruits Tomato Hornworms: Bt and handpicking Cutworms: using rigid collars to protect young seedlings Grasshoppers: poultry food Cucumber beetles: neem, handpicking and good garden cleanup corn earworms: putting a few drops canola/olive oil on the tips of ears right when the silks start to show Whitefly: insecticidal soap/Dawn dishsoap
My sister in southern California would love some resources to help protect her seedlings without chemicals. If anyone finds other good threads for that region, or online articles, would you please post them here?