Nature's chemical warfare: Deconstructing bamboo tar's phytotoxic signature for targeted weed biocontrol

From waste to weed control: bamboo tar emerges as a dual-function bioherbicide and precision pesticide. This study addresses dual challenges of biomass valorization and sustainable agriculture through bamboo pyrolysis tar (BT). We deciphered BT's phytotoxic profile via systematic bioassays, revealing its dual functionality as a plant growth suppressor and eco-friendly pesticide. Following strategic organic acid removal, GC-MS analysis identified a phenolic-rich composition (74 % phenolics) driving bioactivity. Our multi-scale evaluation integrated Petri dish EC 50 quantification (0.08 %-0.45 % across dicots/monocots) with greenhouse simulations (0.6 %-3.0 % efficacy thresholds), culminating in two-year field trials. Three BT formulations achieved 86 %-95 % suppression of Artemisia argyi and Echinochloa crus-galli within 14 days at 2.5 %-20 % concentrations - rivaling commercial vinegar herbicides. Crucially, BT demonstrated equivalent efficacy on broadleaf and narrowleaf weeds, overcoming conventional botanical herbicides' selectivity limitations. The study establishes an optimal concentration window: while 2.5–20 % BT enables effective weed control, insecticidal/fungicidal applications require strict thresholds (<0.6 %) to prevent crop phytotoxicity. Conductivity-change testing confirmed phenolic compounds (e.g., guaiacol) as primary bioactive components, acting through cellular sap leakage induction. These findings position BT as a circular economy solution, simultaneously addressing agricultural waste management and synthetic pesticide reduction through nature-inspired chemistry. Bamboo tar from stand the sediment 90 DAT in bamboo vinegar contained 41 compounds including 74 % phenols. It can control narrow/broad-leaved weeds in growth chamber and field and field trials. • Bamboo tar (BT) is mainly composed of 74.13 %, phenols, 6.64 % ketones and 6.609 % acids. • BT has herbicidal activity components (guaiacol) and can be used for weed management. • Control the dose of BT as insecticide and fungicide to avoid crop damage. • Sensitivity of radish and barnyard grass was higher than that of cucumber and wheat. • Revealed their mechanism: inducing cellular sap leakage.