The bioactive compounds from Argemone mexicana L. extracts control Colletotrichum acutatum in apples and improve postharvest quality

Apple production is affected by Colletotrichum acutatum, the causal agent of bitter rot and commonly controlled with synthetic fungicides that pose environmental and health risks. This study evaluated a methanolic extract of Argemone mexicana L. leaves as a sustainable alternative for this disease control. The extract was characterized by GC-MS and evaluated against C. acutatum in in vitro assays at 10, 15, and 20 mg L−1, followed by an in situ evaluation using ‘Golden Delicious’ apples from an orchard with agronomic management that included nutrition, irrigation and pruning. In harvested apples, the impact of C. acutatum on disease incidence and severity, and postharvest quality parameters were evaluated for 21 days using five treatments: no- inoculated fruits treated with extract (Exam), inoculated fruits treated with the extract (C. acu+ Exam), inoculated fruits treated with Captan, inoculated untreated fruits, and untreated control. GC-MS analysis identified 12 compounds, most of which exhibited antifungal activity. The results of the in vitro assay indicate that the 20 mg L−1 concentration was the most effective, growth inhibition remained above 50%; in the in situ assay, the treatment (C. acu+ Exam) achieved a 50% reduction in disease incidence and an average of 83% in disease severity. Additionally, extract-treated fruits (Exam and C. acu+Exam) maintained firmness, color attributes, soluble solids content, and weight compared to untreated fruits (Control). These results suggest that A. mexicana extract could be a viable solution for controlling C. acutatum disease in apple fruits.