1. Departamento de Ciências Agronômicas e Florestais, Universidade Federal Rural do Semi-Árido- UFERSA, Mossoró, RN 59.625-900, Brazil
2. Departament of Plant Pathology and Ecology, The Connecticut Agricultural Experiment Station, New Haven, CT 06511, U.S.A.
3. Department of Plant Science and Landscape Architecture, The University of Connecticut, Storrs, CT 06569, U.S.A.