Twig Blight
Diaporthe vaccinii
67 host plants · Fungal
Last updated
This profile synthesizes data from multiple published sources. Expert field review is in progress.
In blueberry fields and ornamental plantings, twig blight announces itself through wilting and red-flagged shoots appearing in summer, often accompanied by cankers at the base of infected canes. The fungus Diaporthe vaccinii produces tiny fruiting bodies embedded in the bark that ooze spores during wet weather, and when moisture is high, you may see silvery-looking tissue speckled with black dots around the infection site. The disease starts by infecting flowers during bloom and spreads down into shoots and twigs as the season progresses.
The reason twig blight has become increasingly important in British Columbia blueberry blocks is its ability to infect through both flowers and wound sites, giving it multiple entry routes into your plants. If you grow blueberries, start with certified, disease-free planting stock and prune out infected branches at least 5 to 6 inches below visible symptoms, disinfecting tools between cuts. Some cultivars like Rubel show better resistance than susceptible varieties such as Duke and Legacy, so choose wisely when replanting. Most importantly, maintain good plant spacing and canopy management to keep foliage dry and promote air circulation, which reduces the wet conditions Diaporthe needs to thrive.
Quick Reference
Management
Spring through early summer (April-June); peak during active shoot elongation (BBCH 14-18). New tissue most susceptible.
Spring; cool wet conditions (50-62°F) with 8+ hours continuous leaf wetness. Rain-splash dominates. Optimum: 55-60°F with high humidity.
Cultural Controls
- Purchase healthy planting material and/or do not use plants with injured branches.
- Prune out, remove, and destroy infected and dead branches.
- Prune 5 to 6 inches below symptoms.
- Avoid wounding or injuring plants.
- Encourage plants to harden off in winter to avoid frost damage.
- Provide adequate plant spacing and manage canopy size to promote good air circulation.