Effect of Sakkara Brewing on the Severity of Powdery Mildew Disease of Luffa (Luffa acutangula) and Cucumber (Cucumis sativus L.) under Greenhouse Condition

Abstract

Powdery mildew is one of the major production constraint of cucurbits in almost all parts of Sri Lanka.The disease can be controlled with fungicides. However, bio control agents or organic compounds provide economically sound, practically feasible and environmentally safe approach. “Sakkaraa” brewing (SBr) is a fermented aqueous drink based on cane sugar and yeast (Saccharomyces cerevisiae). Most of the studies assessing the efficacy of yeast as a bio control agent, however, have focused on its effects against some fungi. Two experiments were conducted in parallel to identify the effect of SBr on severity of powdery mildew of Luffa and cucumber varieties under greenhouse condition. Six luffa varieties and twelve cucumber varieties were grown in pots and artificially inoculated with powdery mildew pathogen. Layout of the factorial experiments involving crop varieties and SBr treatments was completely randomized block design with four replications. About 15 days after inoculation of spore suspension of pathogen and when powdery mildew symptoms were well appeared, started the application of diluted SBr on six Luffa varieties and twelve cucumber varieties as an aqueous spray and untreated plants of each Luffa and cucumber variety were kept as control. Disease evaluation and measurements of percentage disease severity index (DSI (%)) of powdery mildew on plants were performed and recorded at flowering stage and fruiting stage. Microscopic observations confirmed that causal agent of powdery mildew of Luffa and cucumber in the country was Podosphaera xanthii. Results of DSI % of powdery mildew in both experiment showed that there was a significant difference between SBr applied treatment and control both at flowering and fruiting stage. Luffa varieties did not show significantly different of DSI (%) of powdery mildew. Popular Luffa variety Naga recorded highest DSI (%) when compared with other tested varieties. Cucumber varieties showed significant difference of DSI (%) of powdery mildew at flowering and fruiting stages. Cucumber var. KWxG17(S) Green and Var. Tunnel Green showed significantly lower DSI (%) of powdery mildew compared to other tested varieties. Results revealed that SBr has remarkable ability of control of powdery mildew and provides an opportunity to produce an effective control tool to protect Luffa and cucumber varieties from powdery mildew disease.