As a lover of grass (turfgrass that is), I have thoroughly enjoyed my fescue lawn this spring and early summer. The ample winter and spring rains had my fescue lawn and many others looking as good as ever. Other than battling some clover, its been a great year for fescue.
However, the arrival of 90-plus temperatures and high humidity have created the ideal conditions for fungal pathogens to attack our once-lush fescue.
Once again this year, I’ve started receiving phone calls that go something like this, "I have dead and dying spots in my fescue lawn. They are straw-colored and seem to be getting larger. What is it? And how can I stop it?"
This problem is common on all turfgrasses, but in particular tall fescue. The disease is known as brown patch, which is caused by the fungus rhizoctonia. Brown patch is the most common of all lawn diseases in Georgia.
Brown patch is usually found during the summer months and is characterized by irregular, sometimes circular areas of brown grass. Upon closer inspection of the leaf blades, you will notice the fungus causes a blight or die back from the tip down to give the turf its brown color.
Environmental conditions that favor brown patch include temperatures above 85 F and high relative humidity. Night temperatures above 65 F are perhaps the most critical environmental requirement for disease development.
Long periods of leaf surface wetness and very high humidity are required for severe disease development to occur. Summer applications of high nitrogen fertilizers will also encourage brown patch development and injury.
By following a few cultural practices, we can lessen the likelihood or avoid brown patch disease. Avoid over fertilization with high nitrogen fertilizers, especially in the heat of summer.
If irrigation is being used, irrigate after midnight and before 10 a.m. Be sure to avoid frequent light irrigation to reduce humidity. Also, allow time during the day for plant canopy to dry.
Anything you can do to increase air circulation will also aid in keeping the foliage dry, thereby decreasing the chance for disease development. If brown patch is a persistent problem, you may want to consider pruning any shrub or tree barriers that contribute to shade and lack of air circulation.
Brown patch disease will continue to spread if not treated with a fungicide. Options for brown patch control include several fungicides such as Mancozeb (Hi-Yield Maneb), Myclobutanil (Immunox), Thiophanate Methyl (Scotts Lawn Fungus Control), and Triadimefon (Bayer Advanced).
One last point to remember is that fescue is a cool season grass and is likely to suffer from our summer heat. If fungicide treatment is too costly, another option is to simply let the disease run its course and be prepared to over seed the lawn in the fall.
Billy Skaggs is an agricultural agent and Hall County extension coordinator. Phone: 770-531-6988. Fax: 770-531-3994.