Brown patch symptoms can vary depending on the grass variety, the soil as well as climate.
Typically, brown patch causes rings or patches of blighted grass that measure from 5" to more than 10' in diameter. It also causes leaf spots and thin rings with brown borders around the diseased patches. During early morning hours, fine strands of grayish, cobwebby fungal growth may be seen along the edges of active patches. This smokey ring soon disappears as the dew dries.
After the leaves die in the blighted area, new leaves can emerge from the surviving crowns. On wide-bladed species, leaf lesions develop with tan centers and dark brown to black margins.
Bown patch favors high humidity and temperatures over 85 degrees during the day and not below 60 at night. On warm season grasses, this disease can be very active in the spring and fall. It also occurs in areas that receive more than 10 hours a day of wetness for consecutive days.
Brown patch infestation is more severe when the grass is cut to a height less than the optimum for the variety of grass.