Lasiodiplodia iraniensis

Lasiodiplodia iraniensis is a fungal species belonging to the Botryosphaeriaceae family, known for causing significant diseases in various woody plants. It is primarily recognized as a causal agent of botryosphaeria dieback, a condition that severely disrupts the vascular system of the host, leading to branch necrosis and general plant decline.

The host range of this pathogen is extensive, encompassing a variety of economically important crops such as citrus, mango, grapevine, and pistachio, as well as many ornamental tree species. The fungus acts as an opportunist, exploiting various wounds, pruning sites, and cracks in the bark to penetrate deeper into the vascular tissues and establish infection.

Key symptoms include the formation of dark, sunken lesions on the bark, which may eventually develop into deep cankers. A classic diagnostic feature is the internal discoloration of the wood, which typically turns dark brown or black. In advanced stages, the canopy may exhibit wilting, leaf chlorosis, and sudden branch death due to the interruption of water and nutrient transport.

The development and spread of Lasiodiplodia iraniensis are heavily influenced by environmental stressors. High humidity, warm temperatures, and physical stress (such as drought or freeze injury) significantly enhance the susceptibility of the host. Spores are primarily disseminated via wind-driven rain and irrigation water, making sanitation an essential practice in any affected orchard or nursery.

Management of this fungus is challenging and requires an integrated approach focusing on prevention and the reduction of the inoculum source:

• Sanitary pruning of all symptomatic wood, ensuring cuts are made well into healthy tissue.
• Sterilization of pruning tools between trees to prevent cross-contamination.
• Application of protective wound sealants to minimize entry points for fungal spores.
• Maintaining optimal tree health through proper irrigation and fertilization to strengthen natural defenses.
• Preventative application of copper-based fungicides during periods of high risk or after pruning.