Requienellaceae

Requienellaceae is a family of fungi within the order Xylariales. These fungi are primarily known for their association with woody plant substrates. While many species in this family exist as saprotrophs on decaying wood, some members can act as opportunistic pathogens, causing necrosis and bark damage in weakened or stressed ornamental and fruit-bearing trees.

The disease mechanism involves the colonization of plant tissue by fungal hyphae, typically starting from mechanical wounds or pruning cuts. These fungi are classified as pathogens that trigger localized bark necrosis and canker-like symptoms. By breaking down the plant's structural tissues, the pathogen disrupts nutrient transportation, leading to the gradual decline of the plant's physiological functions.

Hosts for these fungi include a variety of trees and shrubs, particularly those in temperate climates. The infection is most prevalent in environments with high humidity and poor air circulation, which favor spore germination and colonization. Plants that have suffered from frost damage, drought stress, or insect infestations are significantly more susceptible to infection by Requienellaceae species.

Symptoms of an infestation are often localized. Growers may observe darkening of the bark, the appearance of small, raised black fruiting bodies, and cracking along the trunk or branches. Affected branches often exhibit wilting, chlorosis, and eventually, the death of the distal parts of the canopy. The structural integrity of the affected wood may be compromised over time due to internal decay.

Controlling Requienellaceae requires an integrated approach focusing on hygiene and plant vigor. Key strategies include:

• Strict sanitary pruning practices to remove and destroy infected plant parts.
• Application of protective wound dressings to prevent pathogen entry after pruning.
• Improving site conditions by reducing planting density to ensure proper airflow.
• Consistent use of mineral-based fungicides (such as copper) during dormant periods to inhibit spore formation.