Cane Berry Issue
Greetings. I have 40+ year old cane berries (Nectar berries, part of the Boysenberry family) that I transplanted over to a friends place in Fairview, just outside Gresham. They were good for the first two years, but now have been having some issues. The plants themselves are healthy, with some having 12+ canes per plant and they grow up to 20+ feet in the off season growing crazy like cane berries do. We normally will keep 6 - 8 canes or so per plant. However after we tie them up and the growing season starts, oftentimes the last 4 feet or so of the canes will wither and die and won't produce any fruit. The other parts of the plants are good and produce well. The total length of the canes will be no longer than 8-10 ft. when trimmed. We have even kept only 4 canes on some of the plants, thinking that they may be unable to sustain the additional canes, therefore dying accordingly, but that has not worked either. The soil appears to be good (everything else grows well there but it has not been tested specifically for berries) and they get plenty of sun and water where they are planted. I might add that I have the same plants in SW Portland with no problem whatsoever. I don't have any pictures unfortunately. Any idea what may be causing this issue? Thank you for any advice you can give. Best, Martin
Multnomah County Oregon
Thank you for choosing Ask an Expert for help with your nectar berries (Nectar boysenberries).
There are two insects that can cause damage to canes. The cane maggot and the crown borer both feed inside the cane causing it to wilt and die. Cutting open the cane, just below where the damage begins in early summer, and you may find the larvae feeding.
There are also several cane blights caused by fungi which damage buds and canes.
Photos of the damage would be helpful. Or for an in-person look at the problem, you can take sample canes (with both good tissue and damaged parts) to the Multnomah County Master Gardener office in Montgomery Park at 2701 NW Vaughn St., Suite 450, in Portland. (10:00 am to 2:00 pm, Monday to Friday).
Let me say something about pruning, too. Each cane on these plants (and many other caneberries) will only bloom/produce fruit once. Each fall after harvesting the fruit from a cane, the cane should be cut out—to the ground. Canes that grew up, from the ground, during the growing season, and did not produce flowers/fruit, should be tied up on the wires or trellis. These canes will produce fruit the next season. Be sure the old canes are removed and the new canes are preserved.
For more information about caneberries of all kinds, see Growing Raspberries in Your Home Garden here: https://catalog.extension.oregonstate.edu/ec1306