Allantophomopsis leaf spot

Allantophomopsis leaf spot (Allantophomopsis spp.) is a fungal disease that primarily affects various berry crops, with lingonberries (Vaccinium vitis-idaea) being a notable host. The pathogen is a type of coelomycete fungus that targets the foliage and stems, causing significant cosmetic and physiological damage to the host plant.

The disease is highly specific to certain ericaceous plants. While lingonberries are the primary target, other related species in the Vaccinium genus can also be affected under favorable conditions. The presence of the pathogen is often detected in nurseries and commercial plantations where plants are kept in high-density conditions, facilitating the spread of fungal spores.

Symptoms typically begin as small, discolored spots on the leaves, which gradually enlarge and turn brown or grayish. These spots may be accompanied by small, dark pycnidia on the leaf surface. On stems, the infection presents as necrotic lesions or ulcers that can eventually girdle the stem, leading to the death of the distal parts of the branch.

Development and spread of the fungus are heavily dependent on moisture. Prolonged periods of leaf wetness, high relative humidity, and cool temperatures are ideal for spore germination and colonization. Rain splash and wind-driven water are the primary vectors for moving spores from infected tissues to healthy leaves and stems within the canopy.

The impact of Allantophomopsis on crop health is significant, leading to premature defoliation and reduced plant vigor. If left uncontrolled, the disease can weaken the plants to a point where they are susceptible to winter damage or secondary infections. Prevention is key, focusing on moisture management and the maintenance of plant hygiene to limit the build-up of the pathogen.

• Regular pruning to improve air circulation within the canopy.
• Removal and destruction of infected plant debris.
• Use of disease-free, certified nursery stock.
• Application of appropriate fungicidal treatments if necessary.