Can I control Japanese Beetle grubs now in the soil to prevent them from being a problem during the summer?
No, you cannot prevent Japanese beetle during the season by controlling grubs in your sod during the spring. Japanese beetles are very mobile and will find your vineyard even if you treated for the larvae that are in your soil now. You would have to treat everything for miles around your vineyard for this to even theoretically be effective. You should not treat Japanese beetle larvae in your soil unless you are having actual problems with your sod (such as cut roots).