Diaporthe wilt of actinidia

Diaporthe actinidiae is a fungal pathogen responsible for the disease known as Diaporthe wilt or stem blight, which primarily affects plants of the genus Actinidia, including kiwifruit. This pathogen is considered a serious threat to commercial orchards, capable of causing significant mortality in both young saplings and mature, productive vines.

The primary symptoms of the infection include the formation of necrotic spots on young shoots and leaves, which eventually darken and cause bark splitting. In affected areas, the tissue dies off, and cross-sections of infected branches typically show internal browning of the vascular tissues, which inhibits the transport of water and essential nutrients.

Environmental conditions that favor the development of this fungus include high humidity, prolonged rainfall, and moderate temperatures. The pathogen survives the winter in infected plant debris, bark, or fallen leaves, and spores are subsequently spread by wind, rain splashes, or through contaminated pruning equipment.

The impact of Diaporthe actinidiae is severe due to its systemic nature, leading to weakened plant immunity, premature abscission of leaves and fruit, and eventually, the progressive dieback of the entire vine. This results in substantial economic losses, significantly reducing crop yields and quality.

Management and prevention strategies focus on integrated pest management:

• Regular sanitation by removing and burning infected branches.
• Sterilization of pruning tools after each cut to prevent cross-contamination.
• Application of copper-based or systemic fungicides during the growing season.
• Maintaining optimal planting density to improve canopy aeration and reduce humidity.
• Using high-quality, disease-free propagation material for new plantings.