Cryptodiaporthe canker

Cryptodiaporthe canker is a significant fungal disease caused by pathogens of the genus Cryptodiaporthe. This fungus primarily attacks the bark and cambium layers of woody plants, leading to the development of necrotic lesions. It is categorized as a type of canker disease, which interferes with the plant's vascular system, potentially causing branch dieback and overall tree decline.

The disease affects a wide range of hosts, including various fruit trees like apples and pears, as well as hazelnut bushes and ornamental plants such as lilacs. While some hosts show greater resistance, stressed or damaged trees are particularly vulnerable. The pathogen primarily targets the woody parts of the plant, including trunks and major branches, disrupting nutrient flow.

Visible symptoms often include sunken, discolored patches on the bark, which may eventually crack and develop into open ulcers. In some cases, oozing or gumming may be observed around the infection site. As the infection progresses, the wood underneath the bark often turns dark and necrotic. Complete girdling of a branch by these cankers typically leads to the sudden wilting and death of the distal part of the plant.

The spread of the fungus is favored by high humidity, prolonged rainfall, and moderate temperatures. Spores are disseminated by wind, rain splashes, and sometimes by insect vectors. The infection primarily enters the host through pruning wounds, frost cracks, or mechanical damage. Once established, the fungus can persist in diseased tissues, serving as a primary source of inoculum for subsequent seasons.

Management of Cryptodiaporthe canker requires an integrated approach. The most critical measure is the sanitary pruning of infected branches, ensuring cuts are made well into healthy wood, and disposing of all debris away from the site. Sterilizing pruning tools between cuts is essential to prevent mechanical transmission. Fungicidal applications, particularly those containing copper, can be used as a preventative measure to protect trees, especially following pruning or periods of severe weather.