TECHNICALLY SPEAKING BROWN PATCH (RHIZOCTONIA SPP.)
Identify: Another disease that can infect almost any type of turfgrass, it is most common in tall fescue, St. Augustine grass, perennial ryegrass and centipede grass. Yards with brown patch have: Circular brown patches that can be a few inches to several feet in diameter. A smoke ring can appear on the outer edges, often appearing water-soaked. The grass in the center of the patch can begin growing again giving it a pu- pil-appearance.
Conditions to Thrive: Brown patch most often shows up during hot, humid summer weather. It prefers night temperatures of 65 degrees F or higher at night. This disease favors excess soil moisture, extended leaf wetness and high nitrogen levels.
Photo: John Kaminski
DOLLAR SPOT (SCLEROTINIA
HOMOEOCARPA) Identify: This disease can affect all species of warm- and cool-season grasses. Kentucky bluegrass, tall fescues, bentgrass, perennial ryegrass, zoyziagrass, Bermuda grass and centipede grass are particularly susceptible. Lawns with dollar spot have: 1 to 5 inch in diameter dead spots with straw-colored grass. These dead spots may grow together to form larger patches.
Hourglass-shaped blotches appear on the blades.
Cottony threads of the fungus can be seen on the plant in the morning.
Conditions to Thrive: Dollar spot typically shows up in late spring and early summer. Lawns with low nitrogen are the most susceptible. Heavy thatch and wet grass also support this disease’s development.
Control Methods: Aerate the lawn to reduce thatch and fertilize appropriately to get the nitrogen levels up. Irrigate deeply to prevent drought stress.
Control Methods: Brown patch is best controlled by proper irrigation, don’t overwater. Also avoid heavy applications of nitrogen fertilizer during disease-favorable weather. Increase mowing height and air circulation to dry the turf faster.
RED THREAD (LAETISARIA FUCIFORMIS)
Identify: Fine fescue and perennial ryegrass are the most susceptible to red thread, but it can also affect Kentucky bluegrass, bentgrass and Bermuda grass. Red thread can be misdiagnosed as pink patch due to similar symptoms. Yards with red thread have:
Tan, pink or red circular or irregular patches from 4 inches to 2 feet in diameter. Leaf blade dead at the tip turning tan, light-gray or bleached white color. Thick, red tendrils that protrude from affected leaf blades.
Conditions to Thrive: Red thread thrives in cool, moist weather. It appears frequently in nutrient-poor soils.
Control Methods: Maintain adequate fertilization, especially nitrogen and potassium. Water deep and infrequently TLP
32 The Landscape Professional //May/June 2021 Photo: Kris Lord
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