Can I use beneficial nematodes in my raised bed vegetable gardens to control grubs?
Question:
My raised bed vegetable gardens were infested with grubs last summer and most of my crops failed because of the roots being chewed up by grubs. I applied milky spore last fall but my soil is still infested with grubs. Can I use beneficial nematodes this spring to knock back the grubs before I plant seeds in my beds this spring? Or what about diatomaceous earth in the soil of the raised beds?
Answer:
Frank Wertheim, Extension Educator, Agriculture/Horticulture
White grubs that we typically treat the lawns for with beneficial nematodes are not the same grubs that would be in a raised bed gardens. Milkyspore has not been very effective for treating grubs in lawns here in Maine due to our harsh winters and beneficial nematodes are best applied to lawns (not your raised bed gardens) in late July/early August when the adults are laying eggs in the soil.
I would recommend you continue to garden in your raised beds and when you find any destructive grubs please submit them to our diagnostic lab for identification and control recommendations.