Control of Verticillium dahliae on artichoke stumps using hot-water treatment

Verticillium wilt, caused by Verticillium dahliae Kleb. is a limiting factor in artichoke (Cynara scolymus L.) production in eastern Spain. In Spain artichoke is propagated commercially mainly via stumps, this being an important way for the dissemination of the pathogen. The purpose of this research was to evaluate conditions suitable for hot-water treatment (HWT) of artichoke stumps. In a first experiment, healthy latent artichoke stumps (cv. Blanca de Tudela) were treated at 40, 43, 46, 49, 52, 55 and 58 degrees C for two periods of time, 20 and 30 min. Plants died at 55 degrees C and 58 degrees C, and the plants treated at 52 degrees C had irregular sprouting. The rest of temperatures showed normal development in comparison with controls. There were no statistical differences on yield between controls and 40, 43 and 46 degrees C. Treatments of 49 and 52 degrees C resulted in lower plant production. In a second experiment, healthy latent artichoke stumps were treated at 40 degrees C 60 min, 42 degrees C 45 min, 42 degrees C 60 min, 44 degrees C 30 min, 44 degrees C 45 min, 44 degrees C 60 min, 46 degrees C 30 min, 46 degrees C 45 min and 48 degrees C 30 min. Stumps showed a high percentage of sprouting with adequate plant production. Additionally, infected artichoke stumps were exposed to HWT at 46 degrees C 45 min. After the treatment recovery of V. dahliae from internal fragments was greatly reduced. These results support the aim of developing a HWT leading to an effective control of V. dahliae from artichoke propagating material.