Management of Verticillium wilt in olive orchards,using the soil solarization method and soil application of micro-organisms

Abstract: Verticillium wilt, with causal agent the soil-borne fungus Verticillium dahliae, is oneof the most difficult controlling diseases and a limiting factor in olive production in theMediterranean area. In Greece, the disease is now widespread in main olive-growing zones,where it causes serious damage; disease occurrence seems to be related with the intensifying ofolive tree culture. Disease infections predominantly occur in late winter/spring time and arerestricted during summer while disease symptoms are mainly manifested in late spring andsummer. The control of V. dahliae is difficult because of the absence of specificity of host. Forthe management and restriction of the pathogen, extensive field experiments were conducted inthe region of Halkidiki (Central Macedonia, Greece), for the last four years. Experimentationinvolved evaluating the method of soil solarization (use of transparent polyethylene – PE) aloneor combined with soil treatments of beneficial micro-organisms, which are competitive to V.dahliae. The experiments were conducted in different geographical areas and in different soiltypes. The soil treatments of micro-organisms (commercial products consisting ofendomycorrhizae Glomus coronatum and G. caledomium, Bacillus subtilis, Pseudomonasborealis and Trichoderma harzianum) were used in an attempt to improve olive trees defenseagainst V. dahliae. The results showed that soil application of micro-organisms following soilsolarization was more successful and promising than soil solarization method alone and controltreatments.