Assessment of Enhanced Silicate Application for Improved Pest and Disease Resistance in Commercial Almond Production, Allowing for Sustainable Waste Management

The sustainable management of almond (Prunus dulcis) hulls and shells represents a major challenge for the global almond industry. Although almond hulls possess considerable nutritional value and can be used as livestock feed, concerns about pesticide residues limit their utilisation and pose environmental and economic disposal challenges. Therefore, alternative crop protection strategies that reduce reliance on chemical pesticides while maintaining productivity are required. Silicon has been widely reported to enhance plant resistance against biotic and abiotic stresses, improve nutrient utilisation, and increase crop productivity. This study evaluated the effects of an enhanced potassium silicate formulation applied through fertigation on pest and disease incidence, plant performance, and kernel yield in a commercial almond orchard over two consecutive growing seasons. The formulation contained potassium silicate (50% w/v), amino acids (42% w/v), Complex Polymeric Poly-Hydroxy Acid (CPPA) (1.5% w/v), and water. Treatments were applied twice per season at a rate of 30 L ha−1 and compared with a grower-standard management program. Silicon-treated trees exhibited significantly lower levels of microbial disease damage in both leaves and mature nuts compared with untreated controls. Across the two growing seasons, pest- and disease-related damage to nuts was reduced by up to 59%. Silicon treatment also resulted in substantial increases in oven-dried kernel weight, ranging from 19% to 33% across the evaluated almond varieties. No adverse effects were observed on flower-to-nut conversion, chlorophyll content, kernel nutritional quality, or leaf nutrient status. The findings demonstrate that enhanced potassium silicate fertigation can improve pest and disease resistance while increasing kernel yield in commercial almond production systems. The technology offers a promising strategy for reducing reliance on chemical pesticides and supporting the sustainable utilisation of almond by-products, including their use in livestock feed and bioenergy production.