Physalospora canker

The causal agent of Physalospora canker is the fungus Physalospora perseae. This pathogen is a member of the Ascomycota phylum and is responsible for significant necrotic tissue damage in woody plants. The disease is categorized as a bark canker, which, if left unmanaged, can severely restrict water and nutrient transport, eventually leading to tree decline.

The primary host for this pathogen is the avocado tree (Persea americana). The fungus targets the trunk, scaffold branches, and smaller limbs. Infection sites are typically facilitated by physical damage to the bark, sunscald, or improper pruning practices, which provide an entry point for the fungal spores to colonize the plant tissue.

Symptoms manifest as depressed, necrotic areas on the bark that expand into characteristic cankers. As the fungus colonizes the cambium, the bark often cracks, and the tree may exhibit sap flow or exudation from the affected areas. If a canker girdles the trunk or a main branch, the foliage above the infection site will wilt and eventually die due to the disruption of vascular flow.

The spread and development of the disease are highly dependent on environmental conditions, specifically high humidity and moderate temperatures. Moisture allows for the production and dissemination of spores via wind or rain splash. Trees that are already weakened by water stress, pest pressure, or nutrient deficiencies are significantly more susceptible to infection compared to healthy, well-maintained trees.

Management strategies focus on strict sanitation, including the removal of infected wood well beyond the visible margins of the canker. Pruning wounds should be protected with appropriate sealants or copper-based fungicides. Preventing sunscald by whitewashing trunks and maintaining tree vigor through proper irrigation and nutrition are essential components of an effective prevention program.

• Sanitary pruning of infected limbs.
• Sterilization of pruning tools between cuts.
• Application of fungicides to protect open wounds.
• Monitoring bark for early signs of lesions.