Experimental study reveals that specific herbicides impair soil microbial suppressiveness against Meloidogyne paranaensis, indicating the need for microbiome-safe weed management.
Key Points
To evaluate how five common herbicides affect soil bacterial community composition and the microbially mediated suppression of Meloidogyne paranaensis in coffee agroforestry soil.
Treated herbicide-naïve coffee agroforestry soil with glyphosate, clethodim, flumioxazin, saflufenacil, or pyroxasulfone and evaluated nematode infection in tomato bioassays measuring gall and egg densities across two independent experiments.
Conducted in vitro chemotaxis assays to assess second-stage juvenile nematode attraction to treated microbiomes, and profiled bacterial community diversity and differential abundance using 16S rRNA gene amplicon sequencing and LEfSe analysis.
Saflufenacil and pyroxasulfone significantly increased gall and egg counts per gram of root compared to untreated controls, whereas glyphosate and clethodim produced no significant change in nematode infection.
Microbiomes exposed to saflufenacil and pyroxasulfone attracted juvenile nematodes (chemotaxis index > 0.6), whereas untreated control and glyphosate-exposed microbiomes repelled them.
Saflufenacil and pyroxasulfone depleted beneficial suppression-associated genera (Chitinophaga, Bdellovibrio, Ramlibacter, Thermomonas) and enriched xenobiotic-tolerant genera (Sphingomonas, Cupriavidus).