Brown spot? Did you mean brown patch?
http://aggie-horticulture.tamu.edu/galveston/be_on_the_lookout_for_brown_patch.htm
Did you say 5 acres? Are you serious? Around 800 pounds, 16 bags? I am sure the cost would be outrageous. What if it does not work? Myself, I think fungicides work best in liquid form. It would be best to learn about fungicides and what they do and don't do on a smaller yard with less financial risk involved. Maybe you could subcontract it out to someone who has proper equipment and does a lot of fungicide work.
Maybe someone here who is an expert on St Aug could advise you as to the best fungicide, best volume of water, and most bang for the buck.

 

Duh yes I meant brown patch. I am planning on 15 bags with a price of $85 per bag for a total cost of $1275. I am already committed to this job. I have the product lined up and am scheduled to spread it this Saturday.

 

Kevin,
"Product lined-up"? Don't do it. I know I am from Michigan, so I don't know your conditions. HOWEVER--take a careful look at the Prostar label
http://www.golfventuresonline.com/labels/BAYLETO595.pdf
I says "Brown Patch (suppression)" And you know what "suppression " means. It means that it barely works at all. It also lists Prostar for brown patch as a tank mix with Bayleton (a better fungicide) and in this case it does not say "suppression". Talk to a couple more chemical dealers; get a broader, more diversified opinion. See local experts, whomever you can rely on for unbiased, experienced opinion. Bayleton granular might suit your situation better.
Ric and Greendoctor where are you?

 

5 acres of lawn is 5 lb of Insignia and 55 lb mancozeb DF sprayed in at least 500 gallons. When dealing with diseases, I never have had much confidence in granules. BTW, the cost for those fungicides is a little less or equal to the Prostar granules and the efficacy is much better.

 

Insignia (7.5lb bag)and Mancozeb DF will cost you less than what you will have to pay for the Prostar. In addition, Insignia has more curative properties, have a little left over for another job. And listen to Greendoctor on the amount of water to use. It must get into the soil to be effective while the granular has to breakdown and then get into the soil. True some may be systemic but before that happens with the granular--grass is gone.

 

I agree with the other posts. Liquid is the way to go.

Granular fungicides are what a home owner would use. They need to be watered in and are marginally effective. Liquid fungicide is the best way and the professional way.

4-5 acres will probably not be watered in unless you are dealing with a wealthy customer.

The other question is, "is it really brown patch"? What is the grass type?

Do they need the app?
What will you do if you diagnose the wrong problem?

You also say $85 per bag. Is that your cost or what the home owner is paying? If that is your cost and they are paying more, I can come give you a liquid app and both of us can make a lot of money. Seriously

 

Insignia + mancozeb is a broad spectrum fungicide cocktail. Even then, it has minimal effect on dollar spot. Dollar spot is best treated with 3336 WP or Eagle EW, sprayed in 100 gallons per acre. It is a good idea to be sure of the disease you are trying to treat. Too bad I am not in TX. Spraying lawns with high water volume and pressure is standard practice for me when treating for insects or diseases. Can you drive on this lawn? I normally do jobs like this with a truck mount boom and skid sprayer when the lawn is over an acre. Under an acre is done with a walking boom.

 

We'll assume you've had the problem tested and confirmed as Brown Patch rather than Take-All Root Rot or something else. We'll assume you've discussed the customers expectations, as lawns are rapidly going dormant here, and we are in an extreme drought. Though this isn't a bad time to do a fung app, visible results aren't going to be seen until probably April . . .

You've got your hands full here, buddy. 5 acres of St. Augustine with a fungus . . . a granular fungicide in November . . . a year-long severe drought . . . now showers in the forecast for Sunday night and Monday.

I dunno . . . a questionable product choice, and questionable timing. That's gonna be a big bill to throw at the customer on the promise that he'll be able to see the results in 5 months. Good luck!

 

Can you share a copy of this label? I've sold plenty of ProStar 70WDG for Brown Patch & Fairy Ring but it's sprayable. Does a great job cool season if you're in front of things. I'm not aware of a spreadable formulation & I just cruised Bayer looking.

http://www.backedbybayer.com/BAYER/....com/BAYER/CropScience/BackedByBayer.nsf/id/EN_Golf_Prostar_Product_Information

 

I do have the label and no it is not listed on Bayers website. I believe this is a product made exclusively for Estes, my supplier. The lable lists it as "Estes Prostar 1.5G granular fert with Prostar Fungicide" I think this link shows it.
http://www.bes-tex.com/products.php?kei=997
I have no problem watering it in as the turf has an irrigation system.