The agronomic practices of walnut (Juglans regia) production in Argentina have improved significantly over the last 10 years. New walnut varieties have reduced the average cropping period from 12 to 7 years, in addition to improving the overall economic value of the crop, through greater yield and improved fruit quality. In 1999, disease symptoms were observed on 1-year-old grafted walnuts from the Zavalla locality in Santa Fe province. Primary symptoms were cankers of varying sizes (up to 50 mm) principally on the main stem but also on side branches. On walnut varieties Chandler, Davis and Tulare, cankers were seen in lateral and terminal buds. Fruit symptoms consisted of necrotic brown spots of diameter 20 mm and depth 5 mm. Affected fruit would abscise prematurely. In 2000 and 2001, the same symptoms were detected in a walnut collection of the Facultad de Ciencias Agrarias, Rosario University.Facultad de Ciencias Agrarias y Forestale
