Enhancing Downy Mildew Management in Grapes through Seaweed Extracts, Chitosan and Targeted Fungicide Use

Abstract

Objective: This study aims to assess the integrated use of seaweed extracts, chitosan, and targeted fungicide applications for sustainable management of grapevine downy mildew.  Study Design: The experiment was conducted by the Department of Plant Pathology, University of Agricultural Sciences, Bengaluru, at farmers' fields during 2019 and 2020 Methodology:  Field Experiments were conducted at Harobande village, Chikkaballapur district and at Linganahalli village of Bangalore rural district during fruit pruning season. The trial fallowed a Randomized Block Design (RBD) which had four different schedules with four replications, for each schedule 20 vines were maintained along with untreated control. Results: Among the tested treatments, Schedule 3, which incorporated LBD12 (a seaweed extract) in combination with chemical fungicides, demonstrated the highest reduction in disease severity, achieving 86.26% at Linganahalli and 87% at Harobande which was significantly superior (p <0.05) over all other treatments. This schedule also significantly contributed in enhancing yield and quality attributes. Furthermore, Schedule 2 (LBD3-based treatment) and Schedule 4 (chitosan-based treatment) also exhibited significant reductions in disease severity and enhanced yield performance over the control, though their effects were statistically lower than that of Schedule 3. Conclusion: This study highlights the potential of integrating seaweed extracts and chitosan with the need-based application of low-risk fungicides, offering an effective strategy for managing downy mildew while minimizing resistance development and fungicide residues in vineyards.