Septobasidiales fungi

The order Septobasidiales represents a unique group of basidiomycetous fungi that typically live as parasites on the bark and branches of woody plants. They are frequently found in association with scale insects, forming a protective fungal mat over the insects, which the fungi use as a mechanical base for their development on the host plant.

These fungi primarily affect a variety of perennial crops, including citrus, apples, and pears, particularly in tropical and subtropical climates. The fungal growth colonizes the surface of the branches, often encircling them, which disrupts the normal physiological functions of the bark tissues in those areas.

Symptoms of the infection include the appearance of thick, leathery, or velvety fungal crusts that can vary in color from light gray to reddish-brown or purple. If left unchecked, these fungal mats can cover large portions of the branches, leading to a restricted exchange of gases and, in severe cases, the eventual death of the affected branch sections.

The development of these fungi is highly dependent on environmental conditions, specifically high humidity and moderate temperatures. The spread of fungal spores is facilitated by wind, rainwater, and the movement of scale insects, which provide both a foothold and a source of nutrients for the initial establishment of the colony.

Economic damage is significant due to the weakening of the host tree, which results in reduced yield and increased vulnerability to other pathogens.

• Sanitary pruning of infested branches is a critical control measure,
• managing scale insect populations with systemic insecticides is essential to stop the spread,
• application of copper-based fungicides during the dormant season helps to eliminate established fungal mats.