Milky spore application methods
Milky spore is a biologic for Japanese Beetle grub control. It's available from home improvement stores as a powder that's applied by the teaspoon in a grid pattern across the lawn. Or, as a granulated product that's applied with a lawn spreader. The powder contains much more active ingredient than the granulate, but the granulate is easier to apply. Does one form work better than the other for grub control?
There are better products available for white grub control on the market and Milky Spore provides poor control of white grub control. Multiple years of repeated applications are needed. Furthermore, Japanese beetles are only one of the scarabs that comprise the white grub complex. Milky spore only works on Japanese beetles; thus many of the white grub species are unaffected by this treatment and the grubs would still remain. Other white grub species common to our area include masked chafers, oriental beetles (sometimes the most numerous), possibly European chafer, June beetles, green June beetle and Asiatic garden beetles. Although this year is a good year for Japanese beetles and other white grubs due to the abundant soil moisture, I do not think an application of milky spore will provide much control of white grubs. In the past, leading scientists have questioned the effectiveness of the product because the bacteria was (or is) suspect.
For your specific question, a properly applied rate of the powdered formulation would probably have greater success than the low rate found in the granular formulation. I have not worked with this product and only relay information I have heard from others. I would suggest the use of entomopathogenic nematodes (distributors can be found online) before the use of milky spore. A entomopathogenic nematode I would recommend would be Heterorhabditis bacteriophora. This nematode will search out all white grub species and attack them, and this species is one of the common nematodes available. Also planting flowering plants near the area white grubs have been found will encourage the parasitic wasps (cannot sting people) to visit the area looking for their hosts. These wasps naturally occur throughout the mid-Atlantic.
That's very helpful, Brian. Thanks for taking time to research and respond. Bruce
You are welcome.