Anthracnose (fungus – Colletotrichum graminicola): Anthracnose may kill plants in irregularly shaped patches from several inches to many feet in diameter. The overall color of affected patches goes from reddish brown to tan. Crown tissues become infected and plants yellow and die. The fungus occasionally causes reddish brown spots on leaves. Leaves then turn yellow and finally light tan to brown as they die. Grayish black mycelial mats are often found on lower sheath tissue and stems. Tiny black fruiting bodies (acervuli) form in dead leaves or stems. Cultural practices that reduce disease include: proper fertility, alleviating soil compaction and traffic, and providing adequate soil moisture. Do not apply high rates of nitrogen during periods of drought or high temperature. Water turf deeply and as seldom as possible to avoid stressful conditions. Avoid watering during the late afternoon or evening. Fungicides (See section on Turfgrass Fungicides) may hasten recovery of affected turf.
Take-all Patch, Bermuda Decline, Take-all Root Rot (fungi – Gaeumannomyces graminis var. graminis or avenae): Take-all root fungus (See Photo) is active in fall and winter when there is abundant moisture and moderate temperatures. However, symptoms are often expressed in late spring or early summer when affected turfgrass first experiences the stressful effects of high temperature and dry weather. This disease has the ability to destroy large sections of turfgrass if left uncontrolled. The first symptom is often yellowing of the leaves which eventually die (See Photo). Turf becomes thin as roots, nodes and stolons become infected and plants die. Unlike brown patch, leaves of take-all infected plants do not easily separate from the plant when pulled. Roots become rotted so damaged stolons are easily pulled from the ground, similar to white grub damage. Regrowth of grass into affected areas is often slow and unsuccessful. Controlling take-all is not easy and both cultural and chemical methods should be considered. Good surface and subsurface drainage is important. Irrigate only when required, and infrequent but thorough water is preferred to frequent shallow watering. Verticutting to remove thatch also helps. Aerification alleviates soil compactions and promotes a deeper, more vigorous root system. Balanced fertility is important. If possible, adjust the soil pH in the upper root zone to a range of pH 6.0 to 6.5. Preventive fungicides (See the section Chemical Controls for Turfgrass Diseases) are best applied in the fall since the fungus is thought to be most active at that time.