ETIOLOGY AND MANAGEMENT OF SPRING DEAD SPOT OF HYBRID BERMUDAGRASS IN NORTH CAROLINA, USA

Spring dead spot, caused by fungi in the genus Ophiosphaerella, is a destructive disease of hybrid bermudagrass (Cynodon dactylon × transvaalensis) in temperate and subtropical climates where the turf is exposed to freezing temperatures during winter dormancy. The distribution of Ophiosphaerella species causing spring dead spot in North Carolina was determined. Ophiosphaerella korrae was present in 18 locations and comprised 82% of the isolates collected. Ophiosphaerella herpotricha was present in 3 locations and comprised 11% of isolates, and 7% of isolates could not be identified to species. Inoculation of field plots demonstrated that O. herpotricha is more aggressive than O. korrae in North Carolina. Preventative applications of fenarimol provided the greatest and most consistent reductions in spring dead spot incidence. Azoxystrobin, propiconazole, and tebuconazole provided control in certain experiments, but myclobutanil did not reduce disease incidence. Preventative applications of fenarimol were equally effective in the fall when soil temperatures were between 15°C and 27°C. The method of application did not significantly influence fungicide performance.