Question
I have recently noticed black spots on our grass. when inspecting the "spots", I rubbed a stick on the surface it is powdery and makes a "smokey" effect like messing with ashes from a fire. but the black still remains.  It has spread from 2 spots to about 20 spots over the last 2 weeks. some of the spots are the diameter of a pop can bottom some of a 5gl bucket.  Any idea of what this is or what to do about it?  Thanks

Answer
Ustilago striiformis.  The only Fungus I know with symptoms like these.  It causes a disease of Bluegrass and Creeping Bentgrass called 'Leaf Smut' or 'Striped Smut'.

You can read about it on the website of Viette Nurseries, aPennsylvania retailer:

http://clients.ebluekey.com/cms/vf.phpfilterParam=Stripe+Smut+&filter=GO!&orderB...

The University of Rhode Island Horticultural School posts a helpful essay, 'Some Common Fungal Diseases of Turf':

http://www.uri.edu/ce/factsheets/sheets/turffungaldis.html

Individual blades of infected Grass are streaked with Yellow.  Gradually the blades turn Gray.  Eventually the Black spores erupt on the surface and go poof! when you disturbed.  This is a Cool Weather disease that takes place in Spring and Fall.

Notes the University of R.I. website: 'During hot summer weather, smut symptoms often disappear, but the plants are STILL INFECTED. They are susceptible to various stresses, such as heat and drought, and many will die. Smut symptoms may return in the fall, and the Fungus will continue to live inside the plant until the plant dies.'

See that?

...UNTIL THE PLANT DIES...

OK.  How are you going to get rid of this stuff?

First thing most people want to do is run out and buy a Fungicide.

The last thing you need right now is a Scotts Fungicide.

In fact, if your Lawn had been fertilized properly, it would not have been vulnerable to any of the diseases you are dealing with now -- many Warm Season diseases are triggered by the wrong use of Nitrogen.  Too much or too little.

Unfortunately, it's the same old Scotts message: Buy our Grass, Buy our Fertilizer, Buy our Fungicide, Buy our Weed Killer, give us ALL your money.  You don't have a Fungus problem.  You have a Scotts problem.

Don't believe me?  Let me clarify this for you.

Figure that S of Ustilago striiformis Fungi were ALWAYS THERE in your Grass, just waiting to erupt.  They sit there, dormant in your Lawn, in the Soil.

Don't believe me?  Let me explain.

Let's take Mildew.  It's in the air all the time, right?  And how do we know that?  We know because if you go to take a shower tonight and leave a clean wet towel on the floor, and don't pick it up until next week, there's going to be Mildew on the towel.  No one has to bring it into the house.  We don't have to catch it from anyone.  Thousands of Fungi are EVERYWHERE.  We breathe them, we eat them, we even inject some of them into our bloodstream -- antibiotics.

Grass can be stressed and weakened by Fertilizers like Scotts makes.  Sometimes, too much.   Other times, too little.  Why do you suppose Grass does not get sick ALL THE TIME?  Because like the towel that you hang up after you use it, your Grass does not stay wet for long periods of time.  Pathogenic Fungi have very little time to do any damage.

But there's one more reason.  And that's the presence of GOOD Fungi.

Just by being there, they ruin any chances that Bad Fungi have of taking over the world.

GOOD FUNGI?

Fungi are competitive.  If you have hundreds of different kinds of Fungi in your soil -- which you DO until you put down a Fungus killer -- those Fungi are competing for nutrients, air, real estate.  MOST Fungi are beneficial -- they do GOOD THINGS for the soil.  Many are highly specialized.  They  build barriers around roots that stop pathogens and parasites from attacking.  They live in the soil near the roots and deliver nutrients and water.  They digest Lignin -- the stuff that makes Wood so tough.

But you never hear about Good Fungi.  It's the BAD FUNGI that get all the publicity.

Now, what about Ustilago striiformis?

'Control is seldom required since the disease is rarely severe. Where damage is occurring, an application of nitrogen and deep watering early in the day will stimulate growth and aid recovery. Avoid frequent light watering in late afternoon or evening, as this may promote disease development. If disease is severe, the fungicide Benomyl may be used in late Fall or early Spring.'  Here's their whole speech:

http://www.ext.nodak.edu/county/griggs/lawngarden/lawndiseases.htm

There, you are now an expert in this problem.

Please keep me posted on how things are working out.  Thanks for writing, Joyce.