Low-cost and effective approaches of soil disinfestation of plastic house or open field crops in Greece.
Large-scale demonstration applications of soil solarization were carried out in Greece (2010-2012) to minimize the use of soil fumigants and reduce application costs by evaluating the effectiveness of specific impermeable plastic sheets used singly or combined with half or full dose against soilborne pathogens. In certain areas the trials were focused on the control of Verticillium dahlia and Fusarium oxysporum f. sp. niveum of watermelons in open fields, Phytophthora fragariae, Rhizoctonia solani and Fusarium oxysporum f. sp. fragariae of strawberries and Sclerotinia minor of lettuce in plastic houses. In other cases impermeable plastics and half the recommended dose of fumigants were compared with common polyethylene sheets combined with full dose against Fusarium oxysporum f. sp. radicis-lycopersici, Pyrenochaeta lycopersici and Meloidogyne sp. of tomatoes. Strip mechanical applications of 6 weeks soil solarization with impermeable transparent plastics against Verticillium dahlia and Fusarium oxysporum f. sp. niveum of watermelons resulted in the control of both pathogens, increased fruit weight and total yield and in parallel demonstrated a long-term effect of the method. Similarly manual plastic house soil solarization application demonstrated that two consecutive lettuce plantations could be established followed by a third watermelon plantation within a growing season just after a single soil solarization application. This residual effect was attributed to the extended beneficial action of the method. Restricted symptom development and increased yield were also demonstrated in extensive strawberry plastic house plantations. As for plastic house tomato plantations it was shown that impermeable plastics and half the recommended dose of certain soil fumigants was equal or superior to the use of polyethylene plastic with full the recommended dose. Indeed, combined soil solarization drastically affected Meloidogyne populations and the saprophytic Fusarium oxysporum along with restricted symptom severity due to the nematodes, Fusarium oxysporum f. sp. radicis-lycopersici and corky root rot caused by Pyrenochaeta lycopersici.