Heavy rains for the better part of the last month in St. Charles have helped stimulate the development of brown patch disease in many St. Augustine lawns.
Although typically more prevalent during the fall and early spring, brown patch disease can also occur during winter months when soils become highly saturated and remain wet for extended periods.
Brown patch is caused by the fungus Rhizoctonia Solani and attacks the base of the turf grass leaf sheaths where they are joined at the stolons.
Usually the roots and the growing points of the shoots are not killed but the leaf tissue dies off and turns a brownish color.
A typical early symptom of brown patch is the formulation of a light green patch several inches to several feet in diameter. The patch begins its progression by changing into a distinct yellow color before taking on a brown hue.
This symptom can be easily observed while the grass still has some green growth but is not as easily distinguished during the wintertime when there is no active green growth. In wintertime, the symptom is distinguished by a circular ring with a darker color than dormant grass.
The incidence of brown patch is usually greater on turf grasses growing in low wet areas or on poorly drained soils.
It also occurs more frequently in lawns, including centipede, that are surrounded by trees that contribute to poor air circulation and in lawns that have a heavy thatch problem.
Dethatching in the spring could provide an important benefit to helping discourage the incidence of brown patch reoccurring.
Several fungicides are available through garden supply centers that are effective in controlling brown patch disease. These include Mancozeb, Captan, Maneb, and Daconil.
A minimum of two fungicidal treatments using a pump sprayer or a hose-end sprayer would be needed to provide effective control of the disease. Treatment should include spraying the surrounding healthy lawn areas in combination with spraying infected areas.