Bacterial hyperplastic canker of almond

The main external manifestation of the disease is the formation of specific neoplasms, known as galls or tumors, which develop primarily on branches, trunks, and root collars.

At the initial stage, small light swellings appear on the bark, which gradually increase in size, taking on a rough, bumpy, and distorted surface.

As the tumors grow, the tissues often crack, exposing the inner wood layers, which creates favorable conditions for secondary infections and wood rot.

In cases of severe infestation, branches become deformed, their growth slows down, and if a tumor girdles the entire trunk, the death of the tree is possible.

Leaves and fruit are affected less frequently; however, under high humidity, small necrotic spots with chlorotic halos may appear on them.

The causative agent of the disease is the Gram-negative bacterium Pseudomonas amygdali, which belongs to a group of plant-pathogenic microorganisms.

This pathogen is capable of surviving for long periods in infected plant tissues, bark fissures, and even in the soil adjacent to the root zone.

The bacteria actively multiply in the intercellular space, secreting specific toxins and enzymes that stimulate uncontrolled division of plant cells.

The infection is spread through contaminated nursery stock, gardening tools, as well as rain splash and wind, which transport bacteria to healthy plant parts.

Pseudomonas amygdali exhibits high plasticity, allowing it to adapt to various environmental conditions within almond orchards.

The most favorable conditions for the activation of the pathogen are high air humidity and moderately warm temperatures during the spring period.

Bark damage resulting from spring frosts, pruning, or insect pests serves as the primary entry point for bacterial penetration.

Frequent rainfall during the active sap flow period contributes to the rapid spread of bacterial exudate throughout the tree canopy.

Poor agricultural practices, such as soil waterlogging or excessive nitrogen fertilization, reduce the natural resistance of almond trees to the infection.

Dense, poorly ventilated plantings create a stagnant air microclimate that significantly increases the risk of widespread disease development.

The harmfulness of bacterial canker lies in the systemic inhibition of the tree's physiological processes, including sap flow and nutrient transport.

Infected trees experience significant yield losses because the plant's energy is diverted to combating the pathogen rather than fruit formation.

Long-term disease progression leads to crown deformation and premature death of productive branches, which shortens the orchard's lifespan.

In neglected cases, large cankerous growths can lead to the total death of the tree, causing serious economic losses to agricultural businesses.

An infected orchard becomes a permanent source of infection, requiring strict quarantine measures and the complete removal of symptomatic trees.

The primary control method is the use of healthy, certified planting material that is resistant to bacterial diseases.

It is essential to conduct regular sanitary pruning, where all infected branches are removed, ensuring healthy tissue is cut and the waste is burned.

Disinfecting gardening tools after working with each individual tree is a mandatory condition to prevent the spread of the pathogen.

To protect pruning wounds, treatments with copper-based fungicides are used, which suppress the development of pathogenic microflora on the surface of cuts.

• Maintaining optimal planting density.
• Regular monitoring and control of bark-damaging pests.
• Application of balanced potassium-phosphorus fertilizers.