The role and efficacy of compost tea in sustainable fruit tree production: Current scientific knowledge and future directions

Compost tea (CT) is increasingly recognized as a promising tool in sustainable production, aligning with the principles of enhancing soil biodiversity and reducing reliance on synthetic inputs. This review critically evaluates current scientific knowledge on the role and efficacy of CT, examining its production methods, mechanisms of action, application schemes, and documented effects on fruit perennials and trees. Evidence suggests that when properly formulated and applied, CT can offer multiple benefits for fruit crops, including improved growth, enhanced yield and fruit quality, and suppression of certain diseases. Major barriers to widespread adoption include concerns over human pathogen safety, regulatory hurdles, and the logistical constraints of on-farm production. To transition CT from a practice of promise to a reliable agricultural tool, future research must focus on demystifying the "black box" through microbial and chemical characterization, establishing standardized production protocols, and conducting long-term, context-specific field trials. Investigating synergistic approaches that combine CT with other organic amendments and biostimulants appears to be a particularly promising avenue for unlocking its full potential in sustainable horticulture. • Benefits of CT in fruit trees are promising but less documented than in annuals. • The "black box" of production explains compost tea's variable efficacy. • CT shows promise in fruit crops, but consistent results need more research. • Standardized protocols are key to unlocking compost tea's full potential. • Integrated use with other organic inputs shows the most promising results.