The best time to apply Milky Spore Disease, Bacillus popilliae, is in early August just before the wee buggers hatch so the spores are in the soil for them to partake of as soon as they start eating.

The soil temp needs to be over 55F about Memorial Day would be about min. date for application.

squarefooterg, MSD may take 1 year to become resident in the soil but what that means is the spores have been ingested by the grubs, grown in the grubs, killed the grubs, and are now spores again and are there in the soil. That 1 year has nothing to do with whether or not the spores you apply this year will kill grubs this year, just that after this year you will have a larger population of the disease spores in your soil than is normal. Since the Bacillus popilliae bacterium are very common and present in very low numbers you probably have some in your soil now, just in populations too low to be effective as a grub control.

kimmsr maybe you should read the package label since it take at least one year to start killing the grubs.

That depends on when you apply MSD, when the grubs ingest the spores, and how many grubs you have that ingest the spores. You most likely already have some Bacillus popilliae spores in your soil, they are quite common, just not enough to adequately control grubs in most people minds. If the package label says something about taking a year before being effective that is the packager being very cautious because of the many variables in how people would apply the product, soil types, and how well the stuff would get watered in.