Raspberry Cane & Leaf Spot
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Raspberry Cane and Leaf Spot  Raspberry cane and leaf spot is a fungal disease that affects young canes primarily from late spring to early summer. Spores overwinter on host plants. Fruiting canes develop lesions from infection from the previous year.Susceptible Plants- Raspberry, blackberry, loganberry, and other hybrid berries. Cycle- The spores are released in high numbers and carried to young susceptible leaves and canes by splashing or wind-driven rain. The fungus spores germinate in a film of moisture and penetrate the leaf or cane tissue. As leaf and cane spots form and age, new pycnidia form in the centers. These also produce and release spores that can cause secondary infections throughout the growing season. Although the environmental conditions required for infection are not clearly understood, periods of rainfall are highly conducive to disease development. After overwintering in infected canes or debris, the fungus produces spores for new infections the following spring, completing the disease cycle.
Symptoms- The fungus Elsinoe veneta, which causes raspberry cane and leaf spot attacts young growth. Purple spots are found on canes, leaves, blossoms, and stalks. Leaves may drop, bark can split, and small cankers form. Fruit yield is reduced. Severe infection will cause distortion and death.
Prevention and Control- Cut out and burn infected canes. Practices that increase air circulation within the planting, pruning out infected canes, and treatments with a copper sulfate either alone or in combination with lime sulfur are acceptable for use in an organically certified crop. Other practices to control raspberry cane and leaf spot include proper spacing, thinning to maintain proper cane density, and maintaining narrow rows. These practices lower canopy humidity and allow faster drying of foliage and canes, resulting in less infection. The most important management tool is dormant lime sulfur applications that serve to burn out old lesion and thus reduce sporulation. Fungicidal Spray- Use bordeaux mixture when buds on fruiting canes open then again ten days later. Fungicides such as Bonide Sulfur Fungicide
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