With properly selected cultivars and timely mowing, fertilization, and irrigation, which disease still has the potential to decimate a lawn on a site that receives ample sunlight?

• A. Pythium blight
• B. Brown patch
• C. Dollar spot
• D. Fairy ring

Answer: (A)

Even with good cultivars and timely mowing, fertilization, and irrigation, a lawn can be decimated by Pythium blight because it is driven by leaf wetness and warm, wet conditions rather than by shade or general turf vigor. This disease is caused by water molds that spread rapidly when the turf remains wet from overhead irrigation or rain, forming greasy, water-soaked patches that can merge and kill large areas in a short time. Sunny sites aren’t immune; if leaf surfaces stay wet for extended periods, Pythium blight can take hold and spread quickly, outpacing routine maintenance. To reduce risk, manage irrigation to minimize leaf wetness, improve drainage, and monitor for early signs so you can act promptly. Other diseases tend to cause slower, more patchy damage under good cultural practices, whereas Pythium blight can deliver rapid, extensive damage even in well-managed sunny lawns.