Milky Spore Disease, "Baciilus popilliae" is a passive disease, the grubs need to find it and then ingest it for it to work. That can take time and the best time to apply it is in August when newly hatched grubs would be much more actively feeding. The grubs that will move into the grass root zone this spring will be too big for the disease to work on them.

What is the best way to apply this? Does it need to be dug in to the ground (preferrably in their tunnels?) or is it just as easy to spread on ground and water in?

The directions that came with the product should state that you spread it around and then water it in.

Actually they want you to buy that long cardboard tube and what is not stated is why you'd need a tube if only spreading and watering it in. In only what I can assume is they expect you to jam it into the ground and then perhaps the end has slits in it where some powder is deposited under ground and then it is watered in. I could be completely wrong but the instructions are very vague.

I bought some of this and I will agree, very vague directions. I can not see the logic in the 4' rows and tsp piles. I can not see why you could not mix this with sawdust or something and spread it. I was thinking I could mix some with water and spray it on, since it needs to be watered in anyway.
The only logical reason I could come up with is that the inert powder will help feed the spores, but thats weak if you ask me.
Has anyone had luck in mixing this is a sprayer?

botanicalbill, I think I will try mixing this powder with seed starter or finely screened compost and then load it in a drop spreader and see what happens.

Most everything I have seen about applying Milky Spore Disease is to put down 1 level teaspoon every 3 feet in a grid pattern, ie. some here and then 3 feet away put doen some more. Some people lay out strings every 3 feet in both directions to make a grid to aid in dispensing.

If your in need of a more immediate result for a natural grub kill you can also use Beneficial Nematodes. I believe it begins working in 1-2 weeks when applied at the correct intervals.

Here is a link that might be useful: Benificial nematodes info

Very expensive stuff to use, art1. The beneficial nematodes, if you can afford them, may be more effective in the spring when the targets are too big for the MSD, Bacillus popillea, to do any good. But at about $50.00 per pint to treat 370 square feet that may well be too expensive for many people.

I found a site that sells nematodes cheap. $36 for approx 15k sqft. Seems like a good deal to me,but what do I know.

hgi@hydro-gardens.com

I applied this to my lawn over 4 years ago and it takes at least 3 years to spread around for full coverage. After making a 4' frame out of schedule 40 1/2" pipe, I put a teaspoon of it in each corner. Flipping the frame twice sets up for the next square in the checkerboard application pattern. It takes a while to get it all down as it's a hands and knees job if you have purchased the powder. I have no experiance with the tube applicators.
The reason it takes 3 years to spread is because the grubs have to become infected, then they die and the spores are released from the dead grubs body. The worse your grub infection the faster milky spore spreads. The manufacturer states it will last 10 years. Very cheap treatment considering the amount of time it lasts. At this point I have very few grubs, while my neighbors are still using chemicals and loosing parts of their lawns. I will reapply around 9 years out for the next 10 years of protection. This is on a north central Ohio lawn.

Here is a link that might be useful: St. Gabriel Organics Milky Spore

I would suspect that the 10 year life span the manufacturer states would be how ling the bacterium stay viable if no grubs ingest any, ie they are all dead. As long as there are grubs to ingest this Bacillus popilleae, Milky Spore Disease, and continue to spread it around in your soil it would be viable almost forever.

Can I spread mulch over the milky spore and still have it be effective, or does it have to be exposed?