A SYSTEMIC FUNGICIDE (TETRACONAZOLE) AGAINST THE OLIVE LEAF SPOT, SPILOCAEA OLEAGINA, IN ITALY

Abstract

Peacock spot is also known as olive leaf spot or bird’s eye spot and it is caused by a fungus: Spilocaea oleagina. This very common disease occurs throughout olive-growing regions. Cultivars vary in their susceptibility, but all are subject to infection. Outbreaks are sporadic, and the disease may take several years to become serious enough to cause alarm. Leaves fall prematurely. When significant defoliation occurs, strong bloom fails to develop and crop production is substantially reduced. The most favorite formulations employed to fight against this disease are copper based product. However, the negative environmental effects of this heavy metal are quite a big concern leading to the search for new effective and environmentally friendly molecules. In this study, a new fungicide based on tetraconazole, an active principle with systemic action, was tested and compared to dodine and copper oxychloride. The trial was conducted during the years 2010-2012 in an olive grove of southern Italian with a Mediterranean climate. Two fungicide applications were performed each year. For each formulation employed, seven trees were treated. The disease severity on the leaves was affected by the type of fungicide used and the time of its exposure. From the comparison of control plants with the treated ones, the best results were obtained with dodine and copper oxychloride formulations. Overall, tetraconazole reduced the disease and, as a systemic action, may be associated with dodine or copper to control Spilocaea oleagina particularly when the disease is well developed.