Nattrassia

The first noticeable sign of the disease is the appearance of necrotic spots on the bark, which eventually darken and crack, exposing internal tissues.

A characteristic symptom is branch dieback, which usually begins at the tips and gradually spreads down the trunk of the tree.

Under the infected bark, a black fungal layer—the spore-bearing stage of the pathogen—is often found, giving the wood a specific dark or charcoal-like appearance.

Affected plants exhibit premature wilting of leaves, yellowing, and fruit drop, indicating a disruption of the tree's vascular system.

In advanced cases, the infection covers large structural branches and the trunk, leading to the total death of the plant within one or more growing seasons.

The causative agent of this disease is the microscopic fungus Nattrassia mangiferae (synonym Hendersonula toruloidea). It is a pathogenic organism belonging to the class of deuteromycetes that attacks plant bark and woody tissues.

The fungus can persist in infected wood and plant debris for long periods, waiting for favorable conditions for active reproduction and spore dissemination.

The life cycle of the pathogen includes a phase of active mycelium growth and the formation of pycnidia, which serve as the primary source of infection for new outbreak sites.

Infection spreads mainly through air currents, rain splashes, and contact with contaminated gardening tools or equipment.

A biological feature of this fungus is its ability to quickly penetrate deep into tissue layers through any mechanical injuries or cracks in the bark.

The most favorable conditions for the development of Nattrassia mangiferae are periods of high air temperature combined with moderate humidity.

The fungus is particularly active in regions with hot climates, where plants weakened by sunburn or drought become the most vulnerable.

Poor agricultural practices, such as lack of regular irrigation and imbalanced nutrition, create stress for crops, lowering their natural immunity to infection.

The presence of open wounds on the bark, caused by pruning without subsequent disinfection, significantly increases the risk of infecting healthy trees.

Planting density that prevents proper air circulation and light penetration creates local microclimatic zones ideal for pathogen reproduction.

Nattrassia poses a serious threat to many fruit and berry crops, including citrus, mango, grapes, walnuts, and several types of ornamental trees.

The disease leads to a sharp decline in yields due to damage to the vascular system, which is responsible for transporting nutrients and water throughout the canopy.

Massive branch dieback requires radical sanitary pruning, which distorts the shape of the crown and negatively affects the productive lifespan of the orchard.

Economic losses are caused by both the death of individual trees and the general decrease in the quality of fruit, which become small and deformed.

In large industrial orchards, the infection can spread rapidly, threatening the loss of a significant portion of the crops if not managed properly.

The main preventive measure is maintaining a high level of agricultural practices, including timely irrigation, fertilization, and pest control to prevent tree weakness.

It is essential to strictly follow pruning rules: use only sharp, disinfected tools, and always paint large cuts with protective garden paint.

Sanitary orchard maintenance involves the immediate removal and mandatory burning of all infected branches and fallen leaves where fungal spores accumulate.

• Performing preventive treatments with systemic fungicides at the start of the growing season.
• Whitewashing trunks and major branches to protect against sunburn and bark cracking.
• Monitoring the bark for cracks and providing prompt treatment for any wounds.

If initial symptoms are detected, local removal of infected bark down to healthy tissue followed by disinfection with copper-based preparations is recommended.