Stem Canker of Cat-Tail Willow Caused by Botryosphaeria dothidea in Taiwan

Ko, Y., Sun, S. K., and Lan, C. C. 2003. Stem canker of cat-tail willow caused by Botryosphaeria dothidea in Taiwan. Plant Pathol. Bull. 12:269-272. Cat-tail willow (Salix gracilistyla) has become popular as cut flower for house decoration during Chinese new year in Taiwan in recent years. As a consequence, the acreage of cultivation has expanded to more than 200 hectares, primarily in Ilan County. In a field survey, stem canker was found to be a very common disease on cat-tail willow. Infected twigs were dark brown at first and typical symptoms appeared as small, oval reddish brown lesions each with a deep long fissure in the center. Canker developed and the stem died in the later stage of the disease development. Lesions varied in size ranging from 28-30 6 mm to 60-65 6 mm. Numerous small black fruiting bodies were present in the canker. They were pycnidia and perithecia of the causal agent, Botryosphaeria dothidea. Pycnidia were globose to conical and ostiolate. Conidia were fusiform, elliptical and hyaline, 14.5-26.3 6.5-8.5 m. Each ascus contained eight ellipsoid, hyaline ascospores, 19.2-33.3 8.2-14.8 m. On PDA plate, pycnidia fully matured 7 days after spore germination. Conidia formed in the pycnidia were infectious upon artificial inoculation. Botryosphaeria dothidea is first reported as the causal agent of stem canker of cat-tail willow.