Hello, I live in Hampton roads Virginia (Suffolk) I have a client that has had St. Augustine grass for about 4-5 years. At the end of last year I noticed 3-4 spots of dying grass about 4 ft in diameter each. at that time I applied granular anti fungal treatment. The grass area is in full to mostly full sun and in the winter I overseaded with rye grass. It is august now and the spots have not been thriving to the point of making much need way to knitting together. Further more I have noticed this week a few other areas that the blades of grass are yellowing quite a bit. What is it that is doing this and what do I need to do?