Prompt control of volunteer seedlings and avoiding over-head irrigation is also helpful. Gray mold is a disease of declining tissue that we see in the spring and fall during periods of cool weather with rain and long dew periods. The fungus that causes the disease is sometimes referred to as a mold because the fungus can appear very wooly on as the surface of affected plant organs. This fungus survives as black, BB-like resting structures that persist in the soil. Sanitation, the disposal of infected plant parts is critical to managing this disease.
Several fungicides are also effective against gray mold.
Thiophanate-methyl may have a long, difficult to pronounce name, but it is becoming more widely available as a fungicide for home garden use. It is sold commercially as Domain, Fungo, and 3336. Homeowner packaging of thiophanate-methyl is available from Green Light as Systemic Disease Control. Hot and dry weather put additional stress on lawns, making them more susceptible to the various disease pathogens responsible for the summer patch disease complex. While fungicides can be used to help treat these diseases, often the most important treatment is to examine the cultural practices used on the lawn and modify those to promote a healthier lawn.