Lambertella rot

Lambertella rot is a fungal disease caused by the pathogen Lambertella pruni, which specifically targets stone fruit trees. Belonging to the Ascomycota division, this fungus is known for its ability to cause significant fruit decay during the maturation stage. While it may not be as widespread as other common fruit rots, it remains a serious concern for commercial and home orchardists.

The primary hosts for this pathogen include various species of the genus Prunus, with domestic plums and damsons being the most susceptible. The fungus typically enters the fruit through surface wounds caused by hail, insect activity, or mechanical damage. Once established, the mycelium colonizes the fruit tissue, leading to rapid deterioration and decay.

Symptoms initially appear as small, brownish, sunken lesions on the skin of the fruit. As the infection progresses, these spots expand, and the underlying flesh becomes soft and watery. In humid conditions, small fruiting structures known as apothecia may develop on the surface of the rotted fruit, which serve as the primary source of secondary inoculum for further spread.

The development of Lambertella rot is heavily influenced by environmental factors. High levels of humidity, frequent rainfall, and moderate temperatures provide the ideal conditions for the germination of spores and the subsequent infection of developing fruit. The pathogen overwinters as mycelium or sclerotia within mummified fruits left on the trees or on the orchard floor, creating a persistent cycle of infection.

To manage and control this disease, an integrated approach is necessary. Cultural practices such as regular sanitation, including the removal and destruction of all mummified fruit, are essential to reduce the primary inoculum load. Chemical control involves the application of appropriate fungicides during the growing season, specifically targeting the period between flowering and harvest. Maintaining proper canopy ventilation through pruning is also crucial to reduce humidity around the fruit.

• Sanitary removal of infected fruits
• Application of preventative fungicides
• Control of fruit-damaging insects
• Pruning to improve airflow in the canopy