Cane Diseases
Didymella applanata; Leptosphaeria coniothyrium; Elsinoe veneta
A group of fungal diseases that attack the canes of raspberries and other brambles, the most common being spur blight, cane blight, and anthracnose. They spot, girdle, and kill parts or all of a cane, weakening the planting and cutting the next harvest.
🔎 How to spot it
Spur blight shows as chocolate-brown to purple blotches just below the buds and leaf joints that can enlarge to encircle the cane. Cane blight begins at wounds, where reddish-brown cankers spread under the bark and cause canes to wilt, become brittle, and snap. Anthracnose makes small, round, sunken pits in the bark, gray to pale tan with purplish-red edges. All three may show peeling bark and tiny dark spore structures on overwintered canes.
🥀 Damage it causes
The fungi girdle and kill buds, side shoots, and whole canes, so infected canes wilt, break, or fail to fruit, and yield drops. Spur blight in particular kills the fruiting buds, and cane blight can collapse canes suddenly, especially after they have been wounded or rubbed.
🔬 What causes it
Three fungi, mainly Didymella applanata (spur blight), Leptosphaeria coniothyrium (cane blight), and Elsinoe veneta (anthracnose). All thrive in moist conditions and spread on splashing water, infecting through young growth and, for cane blight, through wounds. Dense, crowded plantings that stay wet are most at risk.
🛡️ Prevent it
Keep plantings open and quick to dry: narrow the rows to about 18 inches, thin out weak canes, and trellis for air movement. Remove and destroy all old floricanes right after harvest along with any infected primocanes, avoid wounding canes, and water at the base rather than overhead.
🧯 If it is already here
Prune out and destroy infected and spent canes to the ground, leaving no stubs, and thin the row to improve airflow. A lime-sulfur spray as buds begin to grow in early spring helps prevent new infections, though fungicides only partly control these diseases, so sanitation and an open canopy are the foundation.
💡 Good to know
Cane blight is the one that turns on wounds, so handle canes gently and prune in dry weather so cuts can heal. Removing spent floricanes promptly after harvest is the single most effective step against all three.
🌱 Plants it affects
3 plants in the library can be affected by this problem
For educational and informational purposes only. Disease management advice is general guidance drawn from university cooperative extension sources; always identify a problem positively and read and follow the label on any product before use, especially around food crops, children, and pets.