First Report of Ophiosphaerella korrae Causing Spring Dead Spot of Bermudagrass in Italy.
In the spring and summer of 2002, bermudagrass (Cynodon dactylon × C. transvaalensis) turf in two golf courses located in Sardinia and Apulia (central and southern Italy, respectively) exhibited circular patches that were 10 to 70 cm in diameter. Patches developed in the spring on cv. Santa Ana in Sardinia and cv. Tifway 419 in Apulia, after the turf broke winter dormancy. Although the turf partially recovered during the summer, damage was evident throughout the year in greens, tees, and fairways. Patches coalesced to form large areas of straw-colored, blighted turfgrass. The symptoms observed on single plants resembled those of spring dead spot (SDS), including the presence of root rotting. The upper leaf blades, upper leaf sheaths, and upper culms of the diseased bermudagrass plants were bleached and dessicated, or dead. Infected roots, stolons, and rhizomes were covered with black ectotrophic mycelium. Isolation from infected roots on potato dextrose agar (PDA), supplemented with 100 mg/liter of streptomycin sulfate, consistently yielded a fungus with gray, fluffy, aerial mycelium that was at first light gray and later becoming darker. The maximum daily growth rates of all isolates on PDA ranged from 3 to 4.5 mm at 25°C. The cultural characteristics and growth rates of the isolates corresponded to those described for Ophiosphaerella korrae (4). Pathogenicity tests were performed on 8-week-old C. dactylon × C. transvaalensis (cvs. Santa Ana and Tifway 419) grown in plastic pots (15 × 15 cm). The substrate (sandy soil/sphagnum peat/perlite, 50:35:15) was infested separately with three isolates of O. korrae grown on autoclaved oat kernels, using 10 infested kernels per pot. Three replicates were used. Blight symptoms developed on inoculated plants after 8 weeks. Noninoculated plants remained healthy. The pathogen was consistently reisolated from inoculated plants. The pathogenicity test was carried out twice. SDS incited by O. korrae was reported in Australia (4) and the United States (1,2). To our knowledge, this is the first report of SDS on warm-season turfgrass in Italy, as well as in Europe. SDS continued to be observed in the following years after its first detection (3). In 2006, the disease was observed in Apulia (southern Italy). References: (1) J. N. Crayhay et al. Plant Dis. 72:945, 1988. (2) R. M. Endo et al. Plant Dis. 69:235, 1985 (3) P. Titone et al. Acta Hortic. 661:491, 2004. (4) J. Walker and A. M. Smith. Trans. Br. Mycol. Soc. 58:459, 1972.