Compost tea for sustainable control of Phytophthora capsici in tomato plants

This study evaluates the suppressive potential of a compost tea (CT) derived from pruning and garden residues and a native Streptomyces isolate (AC-3) with strong in vitro antagonism against Phytophthora spp. Two CT formulations with compost-to-water ratios of 1:5 and 1:3.5 (v/v) were compared to determine whether a more concentrated formulation could maintain its chemical and microbiological quality while facilitating product handling and commercialization. The concentrated CT (1:3.5) exhibited higher electrical conductivity, nutrient content, and microbial abundance without major changes in the overall microbial structure, as confirmed by metagenomic analysis. Dominant bacterial genera included Streptomyces, Micromonospora, and Mesorhizobium, taxa associated with nutrient cycling and biocontrol.