Brown Patch (Rhizoctonia Blight)
This fungus is most likely observed from October thru April when temperatures are below 80 degrees. Therefore, it is indeed a seasonal disease. The disease is triggered by rainfall, high humidity or even excessive nitrogen. It usually appears in a circular pattern turning the grass yellow, brown or even straw colored as the grass begins to die. The entire leaf will pull out from the sheath due to rot. Patches can expand if not treated properly.
A couple tips to help avoid excessive damage: Irrigate only when necessary and only water in the early mornings avoiding water saturation over night. Avoid excessive nitrogen especially readily available forms. This is a disease and can be spread so always mow these areas last and then clean off your blades. There are treatments available and if you have had Brown Patch in the past most likely it will affect the grass again.
Gray Leaf Spot
This a lawn disease that effects St. Augustine grass mainly during the summer months. Its during the heavy rain and warm months that the disease causes the most damage. Gray leaf spot causes thinning, chlorosis and even die back of St. Augustine grass. Its when we have periods of high humidity for extended periods of time that you will actually see the leaf spot on the grass blade and you will notice the decline of the grass. Gray leaf spot can be treated with fungicides and taken care of. However, as a homeowner if you can practice irrigating early morning so the sun dries up the water faster will help. Also, minimize any stress to the grass during the summer months will help keep this lawn diseases damage to a minimum.
Take-all Root Rot
“Take all” is a disease to the turf grass that occurs year round. However, its during the rainy months that the disease causes any damage. Prolonged periods of rain, stress and over fertilization all encourage this disease. This disease causes the roots to die off first so its not real noticeable until damage is done. So proper maintenance of the turf is our best defense against Take-all Root rot.