Optimal nitrogen fertilization reduces disease and pest susceptibility and postharvest disorders in mango

Abstract

High nitrogen (N) fertilization is widely used to increase mango productivity, but excessive N may increase plant susceptibility to diseases and pests. The effects of N rate, source, and application regime on disease development were evaluated in a commercial ‘Shelly’ mango orchard over three consecutive seasons (2022–2024). Their impact on postharvest fruit quality and pest incidence was also investigated throughout the study period. Seven fertilization regimes were tested, including 0, 50, 120, and 200 kg N ha⁻¹ year⁻¹, and different N forms (NH₄⁺, NO₃⁻) or application strategies. Increasing N application rate was consistently associated with higher susceptibility to powdery mildew (caused by Pseudoidium anacardii) and Botryosphaeria dieback (caused mainly by Neofusicoccum parvum). Postharvest decay, including stem-end rot caused by Botryosphaeria and side rot (caused mainly by Alternaria alternata), significantly increased at high N levels, with a lowest decay incidence observed at 50 kg N ha⁻¹ year⁻¹. Excessive N (200 kg ha⁻¹ year⁻¹) also markedly increased jelly seed disorder incidence (up to 53%), whereas lower N rates showed minimal disorder development. N source and application timing had minor or inconsistent effects compared to the total N rate. Pest pressure was generally low; however, fruit cleanliness was highest under 0 kg N ha⁻¹ year⁻¹ fertilization. Overall, moderate N fertilization optimized fruit health and postharvest performance, whereas excessive N increased disease susceptibility and physiological disorders. Moreover, complementary agronomic results from the same orchard indicated that a N-application rate of 50 kg ha⁻¹ year⁻¹ is optimal for maximizing yield.