Leaf blight of Brazil nut (Bertholletia excelsa) caused by Phytophthora heveae

Abstract

A study was conducted at the Instituto de Pesquisas Agropecuárias do Norte (IPEAN), at Belém, Pará state, in order to identify the pathogenic agent of a disease observed in young plants of Brazil nut (Bertholletia excelsa H.B.K.) a few months after grafting. The disease is characterized by spots and blight of young stems and leaves. Through anatomical studies and pathogenic assays of the cultures obtained from diseased tissues, it was proved that the fungus Phytophthora heveae Thomp. causes the disease. The present work represents the first report of this phycomycete in South America. The Brazil nut now is considered a new host of phytopathogen. The most important damages resulted from the attack on plants grafted in the first year of growth, among which the mortality rate was approximately 40%. The disease can be controlled through application of Cuprosan 0.5% and folcid (Difolatan 80 - 0.5%).