Escala diagramática e reação diferencial de clones para Oídio do Eucalipto

Abstract

Several diseases can cause damage to seedlings of eucalyptus and many species have been attacked by Oidium sp., in nurseries, greenhouse and field. In order to assess the severity of powdery mildew on leaves of eucalyptus, a diagrammatic scale was developed and validated with the following grades and severity levels: note (1) - 0 % ; grade (2) - 0,1 to 1,5% ; grade (3) - 1,6 to 3,0% ; grade (4) - 3,1 to 6,0% ; grade (5) - 6,1 to 12,0% ; grade (6) - 12,1 to 25% ; grade (7) -25,1 to 50%. The use of the scale improved the accuracy of the evaluators and provided high repeatability and reproducibility of the assessments of the severity of this disease. The scale was used to determine the severity of powdery mildew in seedlings of five clones of eucalyptus. With this scale it was possible to describe the differences among clones to powdery mildew. Clone 1528 had the lowest incidence and severity of powdery mildew in the greenhouse.