Brown Patch is a fungal disease that appears as straw colored or brown circular patches ranging in size from a few inches to several feet. Also known as “Frog Eye” or “Fusarium Blight”, the symptoms of Brown Patch can closely resemble that of drought stress, but Brown Patch is usually identifiable by a dark purple to grayish-brown border (“smoke ring”) that may appear at the border of the patches, especially in periods of high humidity. Although leaves usually turn brown and die back, a return to cooler weather enables regrowth of grass plant.
Day time air temperatures into the mid-80’s, high humidity, and nighttime air temperatures above 65 degrees together are prime environmental conditions in which this disease thrives in.
Best practices in managing Brown Spot are to water less frequently with longer deep root watering sessions. If possible, avoid watering at night and on humid days.
Read More: https://ag.umass.edu/turf/fact-sheets/brown-patch