page_title: Raspberry leaf spot
section_title: Disease cycle
hierarchical_section_title: Raspberry leaf spot / Disease cycle
caption_attribution_description: English: Raspberry Leaf Spot Disease Cycle
context_page_description: Raspberry leaf spot is a plant disease caused by Sphaerulina rubi, an ascomycete fungus. Early symptoms of infection are dark green spots on young leaves. As the disease progresses, these spots turn tan or gray in color. Disease management strategies for raspberry leaf spot include the use of genetically resistant raspberry plant varieties, chemical fungicide sprays, and cultural practices such as pruning and thinning out canes.
  Raspberries are an important fruit, mainly grown in Washington, Oregon and California. Although they are also grown in the Midwest and northeastern states, the output is not nearly as great due to the colder weathers and shorter growing seasons. S. rubi prefers warmer and wetter conditions, which can make raspberry production very difficult in California.
context_section_description: In spring, when conditions are favorable, ascospores are discharged from perithecia that have overwintered in fallen leaves and canes and disseminate to infect young leaves of raspberry plants. Once infected, the raspberry leaf serves as a nutrient source for the fungus to begin producing secondary inoculum, or conidia, within pycnidia, a survival structure that protects the spores. Conidia can undergo several repeating secondary cycles and re-infect other nearby plants. When the leaves of the raspberry plant begin to fall, perithecia form in the fallen tissue where asci and ascospores will be produced and protected until the following spring. The perithecia are black, found subepidermaly. The ascospores are characterized by a cylindrical, curved shape and are pointed at both ends with four septate usually.
caption: Raspberry leaf spot disease cycle
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