Raspberry plants are dying before fully fruiting.
They have great drainage. I don't see signs of root rot. It is possible that they dried out too much - but they have definitely been getting at least 1 inch per week. Most likely more. They are in above-ground planter boxes. soil type is 1/3 of Pete moss, vermiculite, and compost. Last year they did great without this issue, but it was their first year so they did not get to full height like this year. I live in northwest Washington state. Temp reached 90 degrees once this summer and they are in full sun.
Certified GKH Gardening Expert
Actually, they are probably being overwatered. They are pretty drought tolerant, though less than their blackberry counterpart. They should only be watered when the top 3 inches of soil are bone dry. This will depend on the temperature and humidity of the area, and will not be a regular cycle.
There are many diseases that affect these plants. Many of them have no symptoms besides lack of fruit, and sudden plant death.
I'm afraid you will have to choose different plants for the site that are not related to avoid spreading the disease. Treating for these types of infections are quite futile so you may not ever get any of those bramble berries to grow there.
This article will help you with the care of raspberries: https://www.gardeningknowhow.com/edible/fruits/raspberry/care-of-raspberry-plants.htm