Large Patch. Large patch is caused by the soilborne fungus Rhizoctonia solani AG 2-2 LP. The disease can infect all species of warm season turfgrasses, including St. Augustinegrass, zoysiagrass, centipede and bermudagrass. The disease is apparent during the spring and fall, when warm-season turfgrasses are entering or exiting their period of winter dormancy. R. solani occurs whenever the temperature of the thatch layer is between 50ºF (10ºC) and 70ºF (21ºC), and continuous moisture is available for at least 48 hours. Excessive moisture levels in the soil, thatch, and lower turf canopy encourage large patch development. Factors such as poor drainage, shade, restricted air movement, or excessive irrigation increase the severity of this disease. Rhizoctonia large patch is the most common and severe disease of warm season grasses across the state of Georgia. Circular patches of affected turf are easily observed, ranging in diameter from less than 3.3 ft. (1 m) up to 26.4 ft. (8 m). Leaves of recently infected turf, located at the periphery of the patch, may appear bright yellow and/or orange in color. Some patches may be perennial, recurring in the same location and expanding in diameter year after year. R. solani infection of warm-season grasses occurs on the leaf sheaths, where water-soaked, reddish-brown or black lesions are observed. Foliar dieback from the leaf tip towards the base occurs as a direct result of these leaf sheath infections. The centers of the patches develop thin and sunken areas that may be invaded by weeds.
Management strategies include:
• Establishing a turfgrass species best adapted to your geographical area and situation;
• Making sure that areas are well-draining, as moisture levels in the thatch and soil is an essential aspect of large patch management;
• Preventing and/or alleviating soil compaction;
• Implementing a sound fertility program according to recommended guidelines for your particular turf species and an updated soil test;
• Cutting grass at the proper mowing height for that species;
• Emphasizing cultural and genetic control on home lawns, as few effective fungicides are available for the public to use for large patch management; and
• Applying fungicides in the following classes for commercial turf: carboxamides, benzimidazoles, carbamates, dicarboximides, DMI fungicides, di-nitro anilines, nitriles, polyoxins, and Qo inhibitors.
http://extension.uga.edu/publications/detail.html?number=C1088
Dollar Spot. The dollar spot fungus (Sclerotinia homoeocarpa now named Clarireedia sp) can produce infections on warm season grass as soon as they start to green up. Dollar spot can continue to infect cool season grasses band can still be fully active at on late spring and /or early summer. Excessive moisture on turfgrass foliage and overcast humid days will promote dollar spot epidemics. Excessive thatch layers and compacted soil stresses is important at this time of the year. Monitoring fertility is an important first step to controlling dollar spot.
Chemical control for practitioners: A variety of fungicides are available to professional turfgrass managers for dollar spot control including fungicides containing benzimidazoles, demethylation inhibitors (DMI), carboximides, dicarboximides, dithiocarbamates, nitriles and dinitro-aniline. Several biological fungicides are now labeled for dollar spot control. For a complete and updated list of fungicides available for dollar spot, visit http://extension.uga.edu/publications/detail.cfm?number=SB28
Centipede decline. Centipedegrass Eremochloa ophiuroides can show what is called “centipedegrass decline”. Grass showa a definite yellowing or chlorosis as it greened-up followed by decline and death in late spring and summer, or Failure to green-up in the spring all together. This is difficult to diagnose and avoidance and anticipation is key for management. Factors that contribute to centipedegrass decline include improper plant nutrition, cultural practices, thatch build-up, and soil and water conditions. For ample discussion on preventive and corrective measures vist
For information on centipede decline visit
https://extension.uga.edu/publications/detail.html?number=C1003&title=centipedegrass-decline
Bipolaris leaf spot on bermudagrass
Severe leaf and crown rot, caused by Bipolaris ssp. can occurr in bermudagrass lawns, sport fields, or golf fairways. Initial symptoms of this disease include brown to tan lesions on leaves. The lesions usually develop in spring and fall. Older leaves are most seriously affected. Under wet, overcast conditions,
the fungus will begin to attack leaf sheaths, stolons and roots resulting in a dramatic loss of turf. Shade, poor drainage, reduced air circulation; high nitrogen fertility and low potassium levels favor the disease. To achieve acceptable control of leaf and crown rot, early detection (during the leaf spot stage) is a crucial. Chemical control for practitioners: A variety of fungicides are available for bipolaris leaf spot control including fungicides in the group of strobilurins, succinate dehydrogenase inhibitors (SDHI), demethylation inhibitors (DMI), dicarboximides, dithiocarbamates, nitriles among others.
