Evaluation of Vitamin-Based Biostimulants for Disease Suppression and Sustainable Almond Production Under Commercial Orchard Conditions

Almond (Prunus dulcis) production generates large quantities of hull by-products, the safe utilisation of which can be affected by pesticide residues resulting from conventional disease management practices. Identifying practical approaches that reduce pesticide use while maintaining crop health is therefore an important step towards more sustainable almond production. This study evaluated vitamin-based biostimulants as a potential alternative disease management strategy under commercial orchard conditions. Field experiments were conducted over two consecutive growing seasons in commercial almond orchards in Australia. Eight vitamin formulations containing vitamin B complex, vitamin B1, vitamin C and vitamin E were evaluated for their ability to reduce disease incidence in leaves and whole nuts, together with their effects on chlorophyll content, flower-to-nut conversion, kernel nutrient composition and other production-related parameters. A formulation containing 50 µg mL−1 vitamin B complex together with vitamin B1 consistently reduced disease incidence to levels comparable with the grower standard chemical programme. Selected vitamin treatments also maintained chlorophyll content, kernel nutrient composition and flower-to-nut conversion without adversely affecting crop performance. Overall, the results indicate that vitamin-based biostimulants have the potential to become a practical component of integrated disease management in commercial almond production. Their use may contribute to reducing reliance on conventional pesticides while supporting the sustainable utilisation of almond hull by-products and improving the environmental sustainability of almond production systems.