INCIDENCE OF VERTICILLIUM DAHLIA IN TRADITIONAL ORCHARDS OF THE OLIVE 'ARAUCO' IN NORTHWEST ARGENTINA (LA RIOJA)

Olive cultivation in Argentina has become important due to the increased cultivated area, promoted by tax deferment laws, reaching almost 102,000 ha to date. Accordingly, the traditional olive orchards are also revalued since they are a valuable source of genetic resources adapted to local climatic conditions. Traditional plantations cover about 2000 ha. Verticillium wilt, caused by the soil-borne fungus Verticillium dahliae, is considered the most important disease affecting the crop. In our country, its presence has been detected in the provinces of Córdoba, La Rioja, Catamarca, Mendoza and it is expanding to other areas. A survey was conducted in a traditional olive producing area in northwest Argentina (Department of Arauco, Province of La Rioja) to estimate the magnitude of the disease. The incidence in the districts studied varied from 0 to 9%. Arauco and Los Barros districts were the most affected, with 4 and 9% of the plants surveyed showing disease symptoms, respectively. Overall incidence in the Arauco district reached 3.1%. Incidence levels found are important, implying significant losses in production. The disease also caused plant mortality, which was greater in the Villa Mazan, Machigasta and Los Barros districts. Unfortunately, both the severity and the number of affected plants have increased markedly in recent years. This information provides an overview of the extent of the disease and may be useful for other studies. It also shows the need to search for management strategies to preserve these plantations.