Canadian Forest Service Publications
Temporal occurrence and impact of Scytalidium uredinicola, a mycoparasite of western gall rust. 2001. Moltzan, B.D.; Blenis, P.V.; Hiratsuka, Y. Canadian Journal of Plant Pathology 23: 384-390.
Available from: Northern Forestry Centre
Catalog ID: 21138
Scytalidium uredinicola Kuhlman et al. is considered an important mycoparasite of western gall rust caused by Endocronartium harknessii (J.P. Moore) Y. Hiratsuka (= Peridermium harknessii J.P. Moore). The temporal occurrence of S. uredinicola and its impact on the ability of western gall rust spores to germinate were determined. Scytalidium uredinicola was not isolated from either external or internal tissues of 3- to 5-year-old galls at any time of the year. However, it was isolated from the external, but not internal, tissues of 6- to 9-year-old galls in most months and from both external and internal tissues of 10+-year-old galls in all months. On galls older than 10 years, S. uredinicola overwintered beneath the periderm and colonized developing rust sori prior to peridial rupture in April. Spore viability of western gall rust was consistently reduced by 85% throughout the period of sporulation over two sporulating seasons. Because S. uredinicola requires considerable time to become persistent and perennial, artificial establishment of the hyperparasite in the early stages of gall rust epidemics might be required to make it an effective biological control agent.