Eco-friendly methods for management of downy mildew of grapevines

Abstract

Leaf disc sensitivity assay showed that EC50 value of P. viticola isolates against chitosan was 64.70 ± 12.76 μg l-1 and in field trial foliar applications of chitosan significantly provided 57 per cent control of downy mildew on grape leaves and 70 per cent control on bunch. Three integrated disease management schedules were prepared and implemented in field by substituting 6 fungicide applications with soil application of ISR strains of Trichoderma and Bacillus or foliar application of chitosan or by reduction of 7 fungicide applications by use of activated potassium salt of long chain phosphorus (APSP) with multisite low risk fungicides. The field trial showed that all the schedules were equally effective as farmers’ practice for disease control even with 6 -7 less fungicide applications. In schedule 2 Bacillus DR- 92 recorded more number of bunches and yield per vine, while in schedule 3 with chitosan had better shelf-life. This study brings out the possibility of integrating soil application of microorganisms, with foliar applications of APSP and chitosan along with need based application of low risk fungicides indicates potential for management of fungicide resistance and fungicide residues in vineyards.