Stem end rot

Stem end rot is a destructive fungal disease caused by the pathogen Botryosphaeria rhodina (also known as Lasiodiplodia theobromae). This fungus is a significant threat in agriculture, primarily impacting fruit quality and postharvest shelf life across various regions worldwide.

The pathogen has a very broad host range, causing severe economic damage to economically important tropical and subtropical fruits. Notably, it frequently attacks mango, papaya, and strawberry. The fungus can persist in latent forms within the plant tissue, becoming active as the fruit matures or during storage conditions.

The primary symptom begins as a water-soaked, dark lesion starting at the stem end of the fruit. As the infection progresses, the lesion expands rapidly, turning dark brown or black, resulting in soft rot of the internal tissues. Under humid conditions, a characteristic greyish-black mycelial growth may appear on the surface of the fruit, further indicating the presence of the pathogen.

Environmental conditions play a crucial role in the disease development, with high humidity and warm temperatures being the primary drivers for spore germination and colonization. Spores are easily disseminated by wind and water splashes from infected debris, while the infection process is often facilitated by physical injuries, insect punctures, or stress factors in the orchard.

Managing stem end rot requires a multifaceted approach focused on both field sanitation and postharvest logistics. Recommended measures include:

• Consistent removal and destruction of infected plant material to reduce inoculum levels.
• Application of systemic fungicides during the pre-harvest period to protect fruit quality.
• Sanitizing harvesting tools and crates to prevent cross-contamination between healthy and infected produce.
• Implementing cold chain management and controlled atmospheres to retard the development of latent infections during transit.