Phomopsis of mastic tree

The fungus can survive in infected plant debris, bark, and wood of affected shoots for long periods. Its life cycle includes a conidial stage, which serves as the primary source of spore dispersal during the growing season.

The primary host of the pathogen is the mastic tree (Pistacia lentiscus), common in Mediterranean regions. Under cultivation conditions, the disease can spread to other pistachio species if the microclimate is favorable.

The pathogen enters the plant through mechanical wounds in the bark, pruning cuts, or natural openings in tissues. The fungal mycelium actively spreads within the parenchyma, causing the destruction of cellular structures.

The biology of Phomopsis lentisci is directly linked to moisture cycles. In dry periods, development slows down, but the spores remain viable and become active as soon as humidity increases or rainfall occurs.

The primary symptom of the disease is the appearance of brown or dark-gray spots on young shoots and leaves. As the disease progresses, these spots enlarge, covering significant portions of the foliage.

On the affected areas of the bark, small black dots often appear, known as pycnidia, which are the fruiting bodies of the fungus. They serve as a clear indicator that the disease has entered an active sporulation phase.

Cracking of the bark and subsequent dieback of shoots above the infection zone are common in branches affected by the pathogen. Leaves on infected areas turn yellow, wilt, and drop prematurely.

When major scaffold branches are infected, the tree loses its ability to maintain proper sap flow, leading to the overall weakening of the plant. In severe cases, it results in the death of individual branches or the entire bush.

Visual inspection allows for the differentiation of Phomopsis from other leaf spots by the characteristic darkening of tissues and the well-defined borders of the wood necrosis.

High air humidity and moderate temperatures during spring and autumn facilitate the development of the fungus. Rainfall is a key factor, promoting the discharge of conidia and their movement onto healthy parts of the plant.

Dense pistachio plantings with poor ventilation create an ideal microclimate for the rapid spread of spores within the canopy. Poorly aerated areas often become primary centers of infection.

Mechanical damage caused during harvest, strong winds, or improper pruning creates entry points for the infection. Through these wounds, the pathogen easily penetrates deep into the wood layers.

Poor agricultural practices, such as excessive overhead irrigation, increase the risk of epiphytotics. Water droplets running down the stem contribute to the dissemination of spores across the entire tree.

Timely sanitary pruning and the destruction of plant debris reduce the total inoculum load in the orchard, preventing the accumulation of the pathogen in the soil and on fallen leaves.

The main danger of Phomopsis is the premature loss of leaf surface, which leads to reduced photosynthetic activity and lower yields. The tree becomes exhausted and loses its winter hardiness.

Systematic infection of branches disrupts the crown architecture, requiring drastic rejuvenating pruning and potentially leading to the loss of productive years of the pistachio tree's life.

Fungal infection significantly lowers the quality of the product if spores land on fruit or inflorescences, causing deformation and rotting. The damage is cumulative from season to season.

Infection of the mastic tree by this pathogen can lead to the death of young seedlings in nurseries, causing direct economic damage to agricultural enterprises.

The spread of the disease hinders the export of products, as quarantine authorities strictly monitor commodity shipments for the presence of fungal pathogens.

The foundation of protection is preventive measures: using healthy propagation material and following optimal planting schemes to ensure good air circulation within the canopy.

Regular sanitary pruning of all infected shoots, followed by burning or deep burial of plant debris, is mandatory to suppress the infection.

Disinfecting gardening tools after every tree prevents mechanical transfer of fungal spores. Alcohol-based solutions or chlorine-based disinfectants are recommended for this purpose.

The application of copper-based fungicides as a preventative measure before the rainy season effectively reduces the risk of infection. Treatments should be performed during dormant and active growth phases.

• Regular monitoring of the orchard condition;
• Timely removal of infected branches;
• Treating pruning wounds with protective sealants;
• Management of irrigation to prevent excessive humidity;
• Application of chemical fungicides in accordance with phytosanitary regulations.