Influence of the Use of Double Roof with Increased Ventilation on the Development of Fungal Diseases in a Mediterranean Greenhouse

Mediterranean greenhouses are characterized by the use of passive climate control techniques, thus avoiding energy inputs that would make crop production more expensive. This study was carried out in Almería (Spain), in a greenhouse divided in two sectors. (West sector: with double roof with a pink spectrum converter film combined with an increased ventilation surface, ratio of vent surface/greenhouse surface SV/SC = 26.0%; East sector: acted as a control with only standard ventilation surface, SV/SC = 16.6%). This study analysed the effect of a double roof and an increased ventilation surface on the main fungal diseases in different crops (Solanum lycopersicum L., Capsicum annuum L., and Cucumis sativus L.). Different diseases were found that develop naturally, powdery mildew (Leveillula taurica) in both the tomato and the pepper crop, and early blight (Alternaria linariae) only in the tomato crop. In the case of cucumber crop, three diseases that developed naturally were found, (i) downy mildew (Pseudoperonospora cubensis), (ii) powdery mildew (Podosphaera xanthii) and (iii) gummy stem blight (Stagonosporopsis spp). The sector that combined the double roof and the increased ventilation surface had lower disease levels compared to the control sector, with statistically significant differences.