Phomopsis lentisci

The causal agent of this disease is the fungus Phomopsis lentisci, which is classified within the Coelomycetes group. It acts as a primary pathogen that affects the bark and vascular tissues of woody plants. The infection mechanism involves the colonization of host tissues by mycelium, which eventually disrupts the transportation of nutrients, leading to localized tissue death.

The primary host for this fungus is Pistacia lentiscus, also known as the mastic tree. The fungus generally enters the plant through physical wounds, cracks in the bark, or pruning scars. While it can infect trees of various ages, young or stressed trees are particularly susceptible to severe colonization, which can stunt their growth significantly.

Initial symptoms are characterized by depressed necrotic lesions on the branches, which gradually turn dark brown or black. As the disease advances, these lesions expand, leading to branch girdling and the subsequent wilting of foliage beyond the point of infection. Small, black pycnidia (fruiting bodies) usually erupt through the epidermis of the infected bark, serving as a sign of the pathogen's active state.

The development of Phomopsis lentisci is highly influenced by environmental conditions, specifically high humidity and moderate temperatures. Rainy periods and heavy dews are conducive to the spread of conidia, which are splashed by raindrops onto healthy plant parts. These conditions provide the necessary moisture for the spores to germinate and penetrate the host tissue effectively.

The economic impact of this disease lies in the reduction of plant vigor and the loss of entire branches, which can lead to tree death in severe cases. Management strategies should be multifaceted to ensure success. Key practices include:

• Sanitary pruning of all symptomatic branches to remove fungal inoculum.
• Sterilizing pruning tools between cuts to prevent cross-contamination.
• Application of copper-based protective fungicides during peak humidity periods.
• Maintaining tree health through proper irrigation and nutrition to reduce susceptibility.