“Brown Patch” fungus is the number one fungus problem on cool season lawns in TN!!!!!!!!!
Causes: Heat + Humidity+Moist leaves. It is very similar to athletes foot on grass! It generally begins about late May and can be active thru late August. It requires 60 degree nights to remain active. Right now, in early June 09, it is in high gear!!!
Symptoms: Brown circles from coffee cup size to over three feet in diameter, with most common size about dinner plate size. When observed early in the morning, before dew dries, a grey”smoke” ring will appear in the outer rim of the circle. This ring means the fungus is actively spreading and damaging turf.
Chemical control – Fungicide is expensive! It requires half of the fungicide to prevent fungus as it does to stop it. Therefore, it is smarter to prevent it with a systemic fungicide three times each summer if you don’t want to get damage from the disease. It generally does not kill the turf, but the circles of ugly will remain until fall if not treated.
Cultural Control – Back off on quick release nitrogen! Lawns that are juicy green going into the summer are usually fertilized with large amounts of quick release nitrogen. Succulent, dark green leaves are soft and easy for the fungus to penetrate. Therefore, we switch to organic, balanced fertilization during the summer and back off of the deep green we maintain in spring. Water deeply and infrequently. The number one mistake homeowners make is to water their lawns when air temps are above 75 degrees. Remember, leaf, NOT soil moisture is the main ingredient needed for fungus development. If humidity is really high, that alone is enough moisture alone to ignite the fungus.
General mis-information: “I never got “Brown Patch” when I had weeds, bermuda, and other stuff in my lawn”. I have heard this many times, and it is true. It is not natural to grow a mono stand of cool season grasses, with no weeds and keep it green during high temps. Therefore, if you stop fertilizing, let the weeds and bermuda take over, and generally let nature put what nature wants in your lawn, you will never have a “Brown Patch” problem. However, most people reading this want nice looking lawns. It’s just part of the price we pay for trying to outsmart nature. “If we don’t fertilize, will we still get “Brown Patch”? Not as much, but your grass will be high yellow and “Dollar Spot” fungus will be your new problem. It attacks under fertilized turf. Then you will have ugly yellow turf with brown spots all in it.
Helpful Info: “Can I treat it myself and save some money”? You can treat it yourself, but won’t save much money. There is only one granular fungicide that works for 28 days. PERIOD! That is Heritage granular fungicide. All the other granulars cost a little less, but only last 10-14days. You will have to use the cheaper ones twice to get full recovery. Heritage granular fungicide is availabe at the “vendors I like” section on right side of this page. Expect Heritage granular fungicide to cost a minimum of $6.00/1000sqft at the PREVENTATIVE rate. $12.00/1000sq ft at the curative rate.