As you clean up and prepare your landscape for fall and a long winter's nap don't forget about Japanese beetles and what they are doing right now. What are they doing? If they were in your garden damaging your plants this past summer, then they've laid eggs in your turf grass or turf grass next door, up and down and street and pretty much everywhere grass is growing. Their eggs are probably in the first stage of larvae growth by now (they have three stages). Although larvae are out of sight, they are spending the next nine to ten months living, growing and dining on turf roots. As I mentioned in my earlier blogs, they will live in the turf soil all winter (going deeper when temperatures get colder) and emerge as adults next June or July.
I won't repeat all the protocols in this blog to treat the larvae growing in turf since I covered them earlier, click here to read - Japanese Beetle Blues Part III. Let me add however, if you are going to use the organic product grubHALT!™ only available from Gardens Alive (as of this writing), then you should apply it when temperatures are above 50 degrees. The protein in the product needs to be 50 degrees or warmer to be active for the larvae to eat and be effective. It is okay to apply after aerating the lawn. Just be sure to water the product in right away. Wait several days after applying grubHALT!™ to fertilize the lawn for the final time of the season.
Fall applications to kill the larvae are recommended because as winter progresses and soils get colder, the larvae move deeper into the lawn. So hit them early when they are closer to the surface. Plus they pupate before emerging as adults in the spring and they won't be eating turf roots while in this stage.
Read all of my Japanese Beetle Blogs:
Japanese Beetle Blues 2016
Japanese Beetle Blues
Japanese Beetle Blues Part II
Japanese Beetle Blues Part III
If neighborhoods collectively treated and killed the larvae each fall, adult numbers would be reduced, i.e. less JB beetle blues!
October 2016 - Please note this blog was written a year ago about this time, but is still applicable. The only change is the organic product Btg is not available to purchase on line (as of this writing), so you will have to use other turf products for larvae control as outlined in Dr. Cranshaw's fact sheet.