Black Raspberry concerns
My Black raspberry plants (Jewel) had yellow leaves in early/mid summer. We had a good early harvest with some large berries. Then as the next flush of berries were supposed to start ripening they shriveled up and turned brown or never ripened. Some of the leaves had turned yellow and brown or pale green. Some of the leaves have spots on them. I also had 3 branches snap in half around the middle. This is mostly on old growth, but I have noticed 1 or 2 branches on the new growth that have spots as well. Do you think this is a disease or an iron deficiency or maybe a water issue? I'm not sure where to start on treating my raspberry patch.
Wayne County Michigan
First I'll ask when was the last time you did a soil test in this area? If not within the last 3 years I'd do this to learn what soil fertility, pH and possible deficiencies you have. You can describe you use of the soil test area and get a recommendation based on soil test results. More info here: https://www.canr.msu.edu/uploads/files/Soil_Test9-12RS.pdf
From the photos I suspect you have a fungal disease, possibly grey mold or anthracnose. I'm attaching several websites that will give you more info and treatment recomendations
More info on iron chlorosis that I found... https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1710&context=extension_curall