Lasiodiplodia dieback

Lasiodiplodia species, including the well-known Lasiodiplodia theobromae, are major fungal pathogens that cause severe dieback, cankers, and fruit rots. These fungi belong to the family Botryosphaeriaceae and are known as latent pathogens, meaning they can reside in plant tissues without showing symptoms until the plant is subjected to environmental or physiological stress.

The host range of Lasiodiplodia is extensive, affecting a wide variety of woody plants, including grapevines, citrus, mango, cocoa, and various ornamental trees. It acts as an opportunistic pathogen, readily colonizing tissues that have been weakened by drought, extreme heat, flooding, or improper pruning practices, eventually leading to systemic colonization of the host.

Symptoms typically manifest as necrotic lesions on branches and stems, which may eventually coalesce and girdle the plant part, causing distal wilting and death. Internally, the wood often displays characteristic dark staining of the vascular system. During moist conditions, small black pycnidia erupt through the bark surface, serving as the primary source of inoculum for further disease spread.

The development of the disease is highly dependent on environmental conditions, with high humidity and temperatures favoring fungal growth and sporulation. The pathogen is disseminated primarily by rain splash, wind-borne spores, and contaminated tools used during routine pruning. In modern agricultural settings, human activity is a significant factor in the long-distance transmission of the fungus.

The economic impact of Lasiodiplodia is significant, as it leads to the loss of productive branches, decreased fruit yield, and, in severe cases, the death of entire trees. Effective management relies on an integrated approach focusing on prevention and hygiene.

• Removal and destruction of infected wood to reduce the local spore load.
• Sterilization of pruning tools using appropriate disinfectants.
• Application of protective fungicides to pruning wounds to prevent colonization.
• Improving tree vigor through balanced irrigation and fertilization to minimize stress.