Thank you for your question to eXtension. You don't mention what plants you are seeing this canker disease on, or how you know it is this particular disease. The best I can do is to provide you with some links of articles from some universities on the disease:
- Virginia: http://pubs.ext.vt.edu/450/450-726/450-726.html
- Penn State: http://extension.psu.edu/pests/plant-diseases/all-fact-sheets/botryosphaeria-canker
- Illinois: http://hyg.ipm.illinois.edu/pastpest/200213b.html
- Cornell: http://plantclinic.cornell.edu/factsheets/willowbotryosphaeria.pdf
Please let me know if you have any other questions.