Pleurostomophora richardsiae, Neofusicoccum parvum and Phaeoacremonium aleophilum associated with a decline of olives in southern Italy

In a recent survey of olive groves in the Canosa di Puglia, Cerignola and Foggia areas of southern Italy a serious decline of olive trees was seen. The symptoms comprised a general decline of the trees beginning with foliar browning and leaf drop, wilting of apical shoots, die-back of twigs and branches, and brown streaking under the bark of the trunk, branches and twigs. In more advanced stages of the disease necroses and cankers were observed on the bark. The symptoms were similar to those caused by Verticillium wilt, but morphological and molecular analyses revealed the presence of Pleurostomophora richardsiae, Phaeoacremonium aleophilum and various genera and species in the Botryosphaeriaceae. Pathogenicity tests carried out on young shoots showed that Pl. richardsiae, Pm. aleophilum and Neofusicoccum parvum were pathogenic and capable of causing brown wood streaking. Since Pl. richardsiae was the most aggressive of these three fungi and frequently it was the only one isolated from diseased trees it was considered to be a primary cause of the decline. To our knowledge, this is the first report of Pl. richardsiae as a pathogen of olive trees.