Turf Leaf Spot

Symptoms

• Various species of fungi, such as Dreshlera poea, cause leaf spot in turf grasses. The first symptoms, red to purple spots on leaf blades, can develop into secondary symptoms with the spots growing larger and white flecks appears at the centers. When temperatures rise above 85 degrees, the blight attacks blades at their base causing them to wither and die, according to the Iowa State University Extension.

Conditions

• Leaf spot spreads and becomes a danger to grass turfs only under certain conditions. The disease appears in summer when warm evening temperatures, long dew periods and frequent precipitation coincide. Improper mowing practices, such as cutting grass to a height of less than 2 inches, help spread an outbreak. A low mowing height allows the fungi greater access to the blades' base. Rainy and windy conditions spread the fungi's spores, advises the Purdue University Extension.

Host Turf

• Certain types of grass are less resistant to leaf spot than others. Bluegrass and fescue are particularly susceptibility. Bentgrass, buffalograss and ryegrass are also vulnerable. Garden centers sell varieties of desirable turf grasses with a genetic resistance to leaf spot. A mixture of several different species of grasses; such as a blend of Kentucky bluegrass, tall fescue and ryegrass; can inhibit the fungal growth, reports the Iowa State Extension.

Management

• Good cultural practices help prevent and manage leaf spot outbreaks. Mow your lawn to a height of 2 inches or higher. Do not mow when the turf is wet. Avoid fertilizing in the spring, as excess nitrogen provides favorable conditions for fungal growth. Keep your turf from staying wet for any extended period. Water deeply at infrequent intervals and avoid frequent sprinkling. Avoid watering in the early evening. Use fungicides only as a last resort.