The solar chamber: an innovative technique for controlling verticillium wilt of olive1

Control of olive tree wilt, caused by Verticillium dahliae, is not easy. A simple solar-chamber technique has been developed to achieve effective control. The treated tree is irrigated, the soil is covered by a plastic sheet, and a chamber made of a metal framework covered with plastic sheets is placed over the tree. Trees were exposed for 10, 15 and 20 days. Using this approach the temperature in the chamber reached 55°, and soil temperatures at 5 and 15 cm depth reached 55 and 45°, respectively. It was no longer possible to isolate V. dahliae from infected trees after 15–20 days. Growth of treated trees was improved as compared with the untreated ones. Laboratory studies on the efficacy of dry heat on the survival of V. dahliae in diseased branches showed that 50–55°C was lethal after 1 h. On PDA medium, the fungus was killed in 1 h at 50°C and in 45 min at 55°C.