Question
zip 19380
When is the best time to get rid of grubs?
Two falls ago- we used the milk spore treatment on the lawn, but it did not do the trick (at the moment).
We would like to overseed this spring
and tried to get rid of the grubs problem.

Also, we have partial shaded lawn-- what grass seed do you recommend?  

I appreciate your help.

Answer
Milky Spore Disease -- 'Bacillus popilliae' -- attacks the larvae of Japanese Beetles and their close relatives.  Have a look at the photos on Cornell University's Organic Biocontrol pages.  On one side, a Healthy Japanese Beetle Grub; on the other, one infected with Milky Spore Disease:

www.nysaes.cornell.edu/ent/biocontrol/pathogens/images/bacillus_popilliaeA.html

Cornell authorities tell us Milky Spore Disease was 'the first insect pathogen to be registered in the U.S. as a microbial control agent.'

But ...

They ALSO point out that the ubiquitous Japanese Beetle 'is the EXCLUSIVE host of the strain of B. popilliae which is sold commercially.'

That means it does not make ALL Grubs sick.  Only Japanese Beetle Grubs.

Also, you should be aware that Milky Spore Disease does not work overnight even under the best of circumstances.  The 'incubation period' takes so long that I always recommend you back it up with FASTER methods during the grace period (which can take several YEARS).  Look at it this way:  If someone with the Flu coughs, you don't keel over with the Flu.  It takes days, or weeks, and with some diseases months before symptoms appea.  Then you have to get sick before you die.

That's how it is with the Grubs.

The larvae consume Soil infected with Milky Spore bacteria.  The germs infect them and multiply.  The Grubs get sick and die.  In between there's Winter, when nothing is going on.  This takes time.

Some authorities are having second thoughts about how reliable today's Milky Spore Disease is.  Some suspect that the targeted larvae may be building some kind of resistance to it.  Cornell points out that one Kentucky study suggested the B. popilliae marketed for Grub control were not really that good.  They also observed that even infected, spore-sick Grubs can do as much damage to your Lawn as healthy, disease-free Grubs before they die and release a new crop of Milky Spore.

So the bottom line is, we know Milky Spore Disease is an excellent way to control adult Japanese Beetles.  It might be effective for Grub damage, but it might not be -- and at worst, it could be a marginally useful control measure for your Lawn.  That said, I am very satisfied with the results at my Long Island, N.Y. plot.

Your other options?

In a study done in 2000, researchers ran experiments to compare the
success rate of the most widely used weapons against Japanese Beetle Grubs and the Masked Chafer, Cyclocephala hirta (a major pest in California), including Bacillus thuringiensis (marketed as 'Bt'), Milky Spore Disease, Paenibacillus popilliae, the beneficial Nematodes Steinernema kushidai and Heterorhabditis bacteriophora, and the highly toxic love-to-hate-it Weedkiller, Diazinon.

The WINNER in this Grubs Demolition Derby: the Nematode, Steinernema
kushidai.

An abbreviated abstract is posted on the BioOne website:

www.bioone.org/perlserv/?request=get-document&doi=10.1603%2F0022-0493(2000)093[0071%3ABCAFWG]2.0.CO%3B2&ct=1

Cornell posts a full page on this celebrated Nematode from Japan, where it lives in the Japanese soil:

www.nysaes.cornell.edu/ent/biocontrol/pathogens/nematodes.html

S. kushidai is just what they doctor ordered, they say, when it comes to curing your house and garden of all sorts of pathogenic pests. They LOVE Steinernema at Cornell.  There, scientists have gone on record to call it 'extraordinarily lethal' against its foes.  In fact, they say, 'The only insect-parasitic nematodes possessing an optimal balance of biological control attributes are entomopathogenic or insecticidal nematodes in the genera Steinernema and Heterorhabditis.'

It gets better.

'Most biologicals require days or weeks to kill.  Yet Nematodes ... kill insects in 24 to 48 hours.'

This is the magic bullet you want against your Grubs.

Steinernema nematodes also attack pests ranging from Termites and Fleas to Fungus Gnats.

Now, the bad news.

Where can you get these Steinernema and their Nematode Friends?

Ohio State posts a page listing commercial suppliers of Insect
Parasitic Nematodes:

www.oardc.ohio-state.edu/nematodes/nematode_suppliers.htm

Not an S. kushidai in sight.  Evidently this five-star Nematode is not available for sale outside of Japan yet -- or, if it is, it is part of the proprietary Nematode Zoo sold by some of the more secretive merchants.  Browsing down the (somewhat outdated) list of suppliers on Ohio State's list, the most promising for your needs looks like a Canadian supplier, Natural Insect Control:

www.naturalinsectcontrol.com/company.html

They may be able to obtain the multitalented S. kushidai.  They may not.  Or they may or dissuade you if S. kushidai is not suitable for your purposes (due to climate for instance).  Someone ought to sell these as part of a Nematode Cocktail.  They'd make millions.

I am really out of space here, but I would just like to briefly add another point or two.

It is important to understand what triggered this population explosion
-- if this is indeed what is going on -- with your local Grubs.  In the case of Japanese Beetles, at least, this problem generally seems to afflict large areas of newly disturbed soil.  There are natural pathogens and predators all over the place looking for juicy Grubs to eat.  Starlings -- MASTER Grubs Controllers.  They will annihilate the population, if they come.

If you are living in new construction, with a new plot of recently disturbed soil, the natural controls were eliminated and have not recovered.  Fungus treatments wipe out ALL Fungi including the 'good' Fungi that restrict growth of ones we don't like as well as insect pests.  Something must have happened to decimate those natural controls in our soil.  You just want to identify it so that you don't do it again.... IF you did.

Sorry to be so long winded about this.  I know you had some other questions, but maybe you would like to re-pose them in light of all this new material.

L.I.G.