Dendrostoma canker

The fungal cycle involves the production of small fruiting bodies (stromata) that emerge through the bark. These release spores that are dispersed by wind and rain splash.

Infection primarily occurs through fresh wounds, pruning cuts, or natural openings in the bark. Once inside, the hyphae colonize the bark and cambium layers.

By producing extracellular enzymes, the fungus breaks down cellular tissues, effectively disrupting the vascular system of the tree host.

Laboratory identification of the pathogen involves examining the structure of the stroma, which displays characteristic morphological features unique to the species.

Early symptoms include the appearance of discolored, slightly depressed bark patches on trunks or main branches. The bark often becomes brittle and dry.

Small, dark-colored fruiting bodies become visible on the surface of the infected bark. These are often described as black pustules or bumpy structures.

As the infection progresses, the bark begins to crack along the margins of the necrotic area, eventually forming deep and visible cankers.

The foliage above the infection point often turns yellow, withers, and drops prematurely as the nutrient supply to the distal part of the branch is severed.

Underneath the dead bark, the underlying wood often exhibits signs of necrosis or discolored, decayed patches that hinder sap flow.

High humidity and mild temperatures are the primary drivers for Dendrostoma spore germination and colonization of host tissue.

Trees experiencing physiological stress, such as drought, nutrient deficiency, or overcrowding, are significantly more susceptible to the fungal invasion.

Winter damage, such as frost cracks on the stem, provides the most common entry point for the fungus to establish itself in the early spring months.

Poor orchard hygiene, including the presence of dead wood and the failure to remove infected plant material, allows the pathogen to persist and multiply.

Lack of air circulation within the canopy keeps the bark moist for longer periods, which greatly facilitates the infection process during rainy seasons.

The primary damage caused by Dendrostoma is the gradual dieback of branches, which leads to a significant loss of photosynthetic area and tree vigor.

If a canker girdles the main stem, the entire tree may die. The disease typically persists for several years, slowly exhausting the tree's resources.

Productivity in fruit trees is drastically reduced, leading to smaller yields and poor fruit quality that fails to meet market standards.

The aesthetic value of ornamental trees is compromised by the unsightly necrotic lesions and the resulting thinning of the canopy.

In forest plantations, the disease can spread rapidly, causing significant economic losses and requiring extensive sanitation operations to stop the outbreak.

Sanitation is the most critical management step: all infected branches must be pruned back to healthy wood and immediately destroyed by burning.

Pruning wounds and large cuts should be treated with appropriate sealants or fungicides to protect the exposed tissue from airborne spore infections.

Routine sterilization of pruning tools with alcohol or a 10% bleach solution between cuts is essential to prevent the mechanical spread of the fungus.

Proactive application of copper-based fungicides during the dormant season helps to reduce the fungal inoculum levels on the tree bark.

Promoting overall tree health through balanced fertilization and proper irrigation helps the host plant develop better defenses against fungal pathogens.