Milky spore is actually a bacterium that targets Japanese beetle larvae. It can be applied any time the ground is not frozen but is most effective in late summer-fall as that is when the grubs are most actively feeding. Once the grubs consume the spores and are infected and die, their decaying bodies release billions of new spores that spread and infiltrate in other parts of the garden. The spread of the spore is really dependent on the grubs eating the stuff and spreading it around, so summer/fall applications have the most benefit. However the product has a long shelf life, so if not needed or used now, it can keep in a cool, dry situation until next season.

Milky Spore Disease, " Paenibacillus popilliae", is a passive method of control, the targets must ingest it. When you apply it to the soil does not make much difference as long as the spores are where the grubs can ingest them after they hatch around August. Like other bacteriums used to control insects MSD is effective for only a short period of the grubs life, shortly after hatching.

kimmq is kimmsr

if you insist on going all natural.. and protecting nature...

ask yourself.. why you insist on a non native perfect lawn ...

might make you head hurt

plant some clover.. and various other weeds i call a lawn in my former horse pasture ... and you dont have to worry about things attacking your monoculture ...

ken

"Like other bacteriums [sic] used to control insects MSD is effective for only a
short period of the grubs life, shortly after hatching."

Maybe you are saying that it is effective on the grub only when the grub is a new born. From what I have read, it can remain active in the soil for 15 years or more just waiting to kill a grub after it spreads it.

I wonder if it makes any difference when the spore is applied, not when it is effective.

You can apply Milky Spore Disease anytime the soil is not frozen and it will be effective, eventually. Since the target grubs hatch from the eggs in August you do want to be sure you apply it in time that the spores are where the grubs will ingest them, so like July, maybe June. Applying MSD in late August will have little affect on the current years crop of grubs since it would be unlikely that the spores would reach the grubs before they grew too big for the disease to have an affect on them.

kimmq is kimmsr