Coral spot

Coral spot, caused by the fungus Nectria cinnabarina, is a common fungal disease that affects woody plants, leading to bark necrosis and branch dieback. This pathogen is typically a wound parasite, meaning it exploits damaged tissues, such as pruning wounds, frost cracks, or sites damaged by pests, to infect the host plant.

The host range of this fungus is extensive. It is frequently observed on various ornamental shrubs and fruit trees, with the apple tree (Malus domestica) being a common and susceptible host. While it often colonizes dead wood first, it can quickly invade healthy living tissues, causing systemic damage that leads to the gradual decline of the entire plant.

The most recognizable symptoms of the disease are the formation of small, coral-pink or orange-red pustules on the bark of affected branches. Over time, these reproductive structures turn brown or black. The affected bark becomes sunken, often cracking, and the branch distal to the infection point eventually wilts and dies, as the fungus disrupts the transport of water and nutrients.

The development and spread of Nectria cinnabarina are highly dependent on moisture. Spores are dispersed primarily by rain splash and wind, settling on susceptible wound sites. The disease thrives in humid climates and is most prevalent during periods of prolonged rainfall or cool, wet springs. The fungus survives the winter within the infected twigs, ensuring its persistence in the garden environment year after year.

Control strategies focus primarily on sanitation and cultural practices. It is essential to prune out all infected wood, cutting back into healthy tissue, and removing the debris from the site to minimize inoculum levels. Always sanitize pruning tools to prevent further transmission. Preventive measures, such as maintaining plant health through proper fertilization and avoiding excessive overcrowding, are critical. Protective copper-based fungicides can be applied to reduce the risk of infection in high-risk areas.

• Prompt removal and burning of infected branches.
• Sterilization of pruning equipment with alcohol.
• Painting pruning wounds with protective sealants.
• Applying copper-based fungicides during dormancy.