I bought a small pot of raspberries from Home Depot about 6 years ago and planted them in between a couple of retaining walls, and between a plum tree and an apple tree (fairly shaded). The blended soil was brought in from a commercial landscaping company. They proliferated quite well after that, producing bigger and bigger stalks, and lots of high-quality raspberries. That is, until last summer, when the stalks were half as tall and the berries less prolific and smaller. Even the newer stalks that spread further down were affected. I forgot to add any fertilizer last year, but I didn't do much of that in prior years. They were watered sufficiently. Any idea why this happened? Am I supposed to prune back the old stalks, or something? Thanks, Gary
Thank you for your raspberry question. What you are describing could be as simple as pruning the canes, fertilizing, or needing more sunlight. Lack of sunlight could be from your two fruit trees shading more than the previous years.
On the other end of the spectrum, your plants may be suffering from a fungal disease, a viral disease, or even insects. Rather than paraphrasing, I have included two links, one from OSU and the other from the University of Kentucky. I recommend you read both in their entirety. The OSU document has information from planting to pruning, whereas the UK document is about plant pathology.
If you have any further questions after reading this, please email us back for additional clarification. Good luck and happy gardening.