White grubs in vegetable beds

Asked October 19, 2018, 12:40 PM EDT

I have four raised vegetable beds. As I was amending the soil this fall, I found white grubs in the beds. For the past two years I have been using Sevin to kill the grubs in my lawn. Is Sevin safe to use in vegetable beds, as the label claims? Is Sevin effective in the fall (the label says to apply in spring and summer)? Also, this summer I found a large number of June Bugs in my yard, so how early should I start applying Sevin in the spring?

Josephine County Oregon insecticides horticulture raised beds

3 Responses

Sevin is legal and safe for use in vegetable gardens if you follow the label guidelines. If you have a very low number of grubs in the raised beds you may want to just pick them out, since the level is probably well below the crop damage threshold. If you have a large number of grubs, it will be beneficial to treat. I would suggest starting with one treatment of the soil in early to mid May depending on how warm and dry it is next spring. If it is wet and cool wait until it warms up. Treating now in the fall is not going to be very effective since most of the grubs have become adults and are migrating out of your raised bed. Treating your lawn in spring will also be a good time. I would target late April or early May depending on how warm and dry it is. If it is still wet and cool hold off until we start drying out and warming up into the 60's or 70's.

How do grubs migrate? I thought they spread because they turn into June Bugs, which then deposit eggs wherever they can fly to. Do you have a link that could educate me about June Bugs? Thank you!

Since I haven't seen the grubs and adults you describe as June bugs it is difficult for me to give you details about their life cycle. You may want to take samples of the grubs and adults to an Extension office where the Master Gardeners can ID them. Why I say this is because June bugs or as they more technically are known, Japanese beetles are not suppose to be in Southern Oregon. If they are you should contact the Oregon Department of Agriculture to let them know. The ODA is working on an outbreak in Eugene and in Sutherlin in my area. Just go online to ODA.gov and look for invasive pests within the plant division.

To answer your question about where the insects lay their eggs is around host plants often in the soil. It often takes several seasons using pheromone traps to catch the adults and treatments to the soil to control them. Once you ID the insect more exactly you can look up the pest life cycle on any Extension website to better understand the pest and how to control it. Below is a link to the ODA for reporting pests.

https://www.oregon.gov/ODA/programs/IPPM/Pages/AboutIPPM.aspx