Soil biosolarization for Verticillium dahliae and Rhizoctonia solani control in artichoke crops in southeastern Spain

The efficacy of soil biosolarization for the control of Verticillium dahliae and Rhizoctonia solani fungal pathogens was evaluated over two consecutive artichoke crop cycles in southeastern Spain. Soil biosolarization was applied in mid-June for 42 days. The evaluated soil treatments were: fresh sheep manure (FSM); beer bagasse (BB) plus FSM; broccoli crop residues plus FSM; and a control of non-disinfestated and non-amended soil. Different variables were analyzed: i) soil temperature during biosolarization; ii) soil inoculum density of Verticillium before and after biosolarization; iii) infectivity of V. dahliae and R. solani introduced inoculum after biosolarization treatments at 15 and 30 cm soil depth through bioassays; iv) crop disease incidence; and vi) marketable yield. Treatments were randomized in a complete block design with four replicates. Biosolarization treatments reduced levels of both fungal pathogens in both years and had significant lower percentages of affected plants at the end of the crop. All biosolarization treatments significantly improved marketable yield 22-29% to 38-59% compared to the non-disinfestated control in 2015-2016 and 2016-2017 crop cycles respectively. Biosolarization with different organic amendments can be recommended as an effective management strategy for the control of soil-borne fungal diseases in artichoke crops in southeastern Spain, especially in repeated monocultures which are cultivated intensively.