Biotic Stresses in Temperate Fruit Crops: Mechanisms, Challenges and Sustainable Management Strategies

Abstract

Temperate fruit crops such as apple, pear, peach, plum, and cherry constitute an important component of global horticultural production. However, their productivity is severely constrained by a wide range of biotic stresses caused by pathogenic microorganisms, insect pests, and plant-parasitic nematodes. These biotic agents significantly reduce fruit yield, quality, and orchard longevity, resulting in substantial economic losses worldwide. Major diseases such as apple scab (Venturia inaequalis), fire blight (Erwinia amylovora), and brown rot (Monilinia spp.), along with insect pests such as codling moth (Cydia pomonella), represent major threats to temperate fruit production systems. Plants have evolved sophisticated defense mechanisms to perceive and respond to invading pathogens and pests, including structural barriers, biochemical responses, and molecular immune signaling pathways. Key components of plant immunity include pattern-triggered immunity (PTI) and effector-triggered immunity (ETI), which together form a multilayered defense system. Advances in plant pathology and biotechnology have led to the development of integrated management strategies aimed at mitigating biotic stress. This review provides a comprehensive overview of major biotic stresses affecting temperate fruit crops, their mechanisms of infection, and plant defense responses. The review also highlights modern approaches such as integrated pest management (IPM), biological control, host resistance breeding, RNA interference (RNAi), microbiome engineering, and genome editing technologies that offer promising solutions for sustainable fruit production.