W. Zhang and
Z. B. Nan, State Key Laboratory of Grassland Agro-Ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, P.O. Box 61, Lanzhou 730020, China; and
G. D. Liu, Tropical Crops Genetic Resources Institute, Chinese Academy of Tropical Agricultural Sciences, Key Laboratory of Tropical Crops Germplasm Research Utilization, Ministry of Agriculture, Danzhou 571737, China
Hybrid bermudagrass (Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davy) is widely used on golf course putting greens in southern China. In September 2011, circular pink patches ranging from 10 to 20 cm in diameter were observed on putting greens established with cv. ‘Tifgreen’ on a golf course in Haikou, Hainan Province. There were approximately 50 pink patches on a putting green. Infected leaves were covered with pink, gelatinous fungal mycelium, which resulted in the production of chlorotic lesions. Lesions expanded, became water-soaked, and leaves died basipetally. A pink fungus, characterized by the presence of clamp connections, was consistently isolated from leaves of infected plants on a potato dextrose agar amended with 0.01% gentamicin sulfate. Based on morphological characteristics, the fungus was preliminary identified as Limonomyces roseipellis Stalpers & Loerakker, the causal agent of pink patch of turfgrass (2,3). To verify the identity, the internal transcribed spacer (ITS) of rDNA was amplified and sequenced using primers ITS1 and ITS4. Comparison with sequences in the GenBank database revealed that the ITS sequence (Accession No. KC193592) showed 98% homology with the sequence of L. roseipellis (EU622846). For pathogenicity tests, inoculum was prepared by culturing the fungus on an autoclaved mixture of 100 g of rye grain and 20 ml water for 3 weeks at 25°C. Six-week-old C. dactylon plants in 10-cm pots were inoculated by placing 2 g of infested grain in the center of the turf canopy, or 2 g sterilized, uninfested grain as a control, with four replications of each treatment. After inoculation, pots were covered with translucent plastic bags and placed in a greenhouse at 24 ± 2°C with a 12-h photoperiod (1). After 3 weeks, more than 70% of leaves in the infested pots showed symptoms identical to those observed under natural conditions while control plants remained asymptomatic. The fungus was reisolated from symptomatic plants. To our knowledge, this is the first report of L. roseipellis causing pink patch on hybrid bermudagrass in China.
References: (1) L. L. Burpee and L. G. Goulty. Phytopathology 74:692, 1986. (2) J. D. Kaplan and N. Jackson. Plant Dis. 67:159, 1983. (3) J. A. Stalpers and W. M. Loerakker. Can. J. Bot. 60:529, 1982.