KEYS TO IMPROVE THE JAPANESE PLUM ORGANIC FARMING IN MEDITERRANEAN CLIMATE CONDITIONS

Organic farming of stone fruit trees is limited in Europe due mainly to the difficulties related to the control of pests and diseases. Furthermore, the difficulty to obtain a good tree vigour and yield by using only organic fertilizers is also another vital challenge. The different susceptibility of plum cultivars to pathogens could be used as an appropriate tool to control pests and diseases. In relation to fungal diseases, shot hole severity was low and only ‘Santa Rosa’ and ‘Larry Ann’ cultivars showed significant susceptibility. Only the cultivar ‘Red Beaut’ showed a high susceptibility to powdery mildew. Rust was the most important disease in most of the cultivars. ‘Showtime’ and ‘Friar’, were the most susceptible cultivars and ‘Red Beaut’ and ‘Souvenir’ the most tolerant. Very important pests affect stone fruits in Mediter-ranean climate conditions. The effectiveness of some natural products allowed in organic farming against different pests and diseases was evaluated. Sulphur was effective against powdery mildew but this compound did not control adequately the rust disease which had the major depressive effect on the trees. Besides, sulphur showed a good effectiveness against red spider and plum gall nut. Aphid populations were maintained at moderate levels by application of a mixture of potassium soap and natural pyrethrins. A yearly application with neem oil was used against the San José scale insect. A strategy of mass trapping with a mixture of pheromones was used to control the Mediterranean fruit fly. Likewise, the control of flatheaded rootborer could be achieved by biological control using an entomopathogenic nematode, Steinernema carpocapsae.