With a summer full of rain, Florida homeowners need to be on the lookout for take-all root rot. This fungus naturally occurs on the roots of turf year-round in many lawns, but only becomes a problem with prolonged periods of rain or when a lawn is stressed. The initial symptoms appear on the roots, but you're unlikely to notice them. If the turf is not being correctly watered, fertilized, or mowed, symptoms will begin to show above-ground as irregular yellow or light-green patches. Then the grass will begin to thin and die. By this time, the damage is done, so your best bet is prevention. Avoid overwatering and fertilizing too much or too often. ---"Take-all Root Rot", Gardening in a Minute