Disease Management Strategies For Controlling Spring Dead Spot And Frequency Of Occurrence Of The Causal Organism Ophiosphaerella Korrae On 'Tifway' Bermudagrass (Cynodon Dactylon X C. Transvaalensis)
Mississippi State University
Munshaw, Gregg C.
Baird, Richard E.
Date of Degree
Graduate Thesis - Open Access
Master of Science
College of Agriculture and Life Sciences
Department of Entomology and Plant Pathology
Spring dead spot (SDS) is the most destructive disease of bermudagrass and its hybrids, affecting intensively managed bermudagrass turf that is at least three years old. This bermudagrass disease is most prevalent in the United States where winter temperatures become cold enough to induce dormancy. The symptoms of SDS appear as sunken, necrotic patches of turf ranging from several centimeters to greater than 0.5 m in diameter. Field studies were conducted at Old Waverly Golf Club in West Point, MS on a Tifway bermudagrass fairway beginning January of 2005 and concluding December of 2006 to determine the frequency and the effects of soil temperature on occurrence of O. korrae in bermudagrass. Characterization of O. korrae isolates was conducted based on optimal in vitro growth temperatures and greenhouse pathogenicity studies. Cultural, nutritional, and chemical management practices were evaluated on the bermudagrass fairway for the reduction of SDS severity, promotion of improved turf color, quality, root health, and reduction of the thatch/mat layer. Treatments included core aerification with and without topdressing, vertical mowing, manganese, elemental sulfur, and myclobutanil fungicide applications. Each year was divided into seasons (winter, spring, summer, fall) based on the bermudagrass growth cycle in Mississippi. The frequency of O. korrae occurrence ranged from 14% in 2005 to 16% in 2006, and was similar for all treatments. Ophiosphaerella korrae occurrence was greatest in the winter and spring compared to the summer and fall. There was no direct association between mean soil temperature and frequency of O. korrae occurrence. Spring dead spot severity ratings were similar in 2005 and 2006. Vertical mowing had a significant effect on fall turf color in 2005 and fall turf color and quality in 2006. The aggressive cultural practices (i.e. vertical mowing, aerification) were the most consistent treatments for significantly reducing the thatch/mat layer and improving root health.
Perry, Hunter D., "Disease Management Strategies For Controlling Spring Dead Spot And Frequency Of Occurrence Of The Causal Organism Ophiosphaerella Korrae On 'Tifway' Bermudagrass (Cynodon Dactylon X C. Transvaalensis)" (2007). Theses and Dissertations. 1526.