Asked August 29, 2016, 5:59 PM EDT

The leaves in my raspberry plants are turning brown and drying up. They started on the new canes looking great but all summer have been getting worse. I asked a commercial farmer earlier in the season and he told me it too much water. So I have cut way back. These are Cascade Delight and I had some Lathams before that did the same thing. Those also got crumbly berries so I replaced the whole row.

Multnomah County Oregon raspberries diagnosis of plant problems horticulture

5 Responses

Thank you for attaching an image to your inquiry. Unfortunately, the wilting of the fruiting canes, along with your comment that “… all summer [they] have been getting worse” is of concern especially when the primocanes (canes which will fruit next year) look fine. That combination usually indicates root rot by a disease-causing fungus which is very common in local soils.

If the roots have root rot, they will be shortened and black. To check if that is so, dig up an affected clump, set it on a tarp to prevent scattering the soil-borne organisms so that you can take a close look. If the roots are creamy and sturdy, perhaps the problem is insufficient moisture. In that case, be certain the soil is thoroughly moistened by what appears to be a soaker hose. (Stick a trowel in the soil to check.)

If the roots are rotting, but you still want to grow raspberries, it’s best to start a new bed with fresh plants. Unfortunately, curative chemicals are not available for use in home gardens.

If you do start a new bed, don’t transplant any of your current plants to the new site because you will also move the disease organisms which are in the soil. Instead, obtain fresh stock from the garden center early next year.

Plant resistant cultivars if available. 'Chilliwack', 'Meeker', 'Sumner', and 'Summit' are moderately resistant. Young 'Meeker' plants are very susceptible but mature plants seem to have some tolerance. Avoid 'Canby', 'Comox', 'Qualicum', 'Malahat' and 'Skeena' are very susceptible; 'Amity', 'Chilcotin', 'Nootka', and 'Willamette' are susceptible.

Because Cascade Delight is supposed to be tolerant to root rot, I wonder if you planted into the same bed where the previous berries grew. But, to be frank, I’m puzzled. Even if you did that, ’Latham’ is also considered to be resistant to root rot. Is there more to this story?

These publications should be helpful to you: “Growing Raspberries in Your Home Garden” http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/18936/ec1306.pdf and “Raspberry Cultivars for the Pacific Northwest” https://catalog.extension.oregonstate.edu/sites/catalog/files/project/pdf/pnw655.pdf). This document lists Cascade Bounty as having excellent resistance to root rot.

Thanks for getting back to me. The canes that are drying up are next year canes, the new ones that started growing early this summer. I did what you suggested and dug up a plant and the roots did not appear to have rot

Thank you for sending the additional pictures. Even though the roots are still rather long, the dark color reveals they are unhealthy.

The soil scattered on the tarp appears very dry and crumbly. So I’m still concerned about a potential issue with irrigation. When you said you “cut way back,” I still wonder how long, also how often, you currently run the system. And, after you run the system, please determine how deep and wide the soil is moistened by probing with a trowel. Perhaps the issue is insufficient water.

In the meantime, please compare your roots to those in the attached image posted on a website for commercial growers in the UK. The light-colored roots are healthy; the dark-colored roots are affected by root rot. (http://www.hutton.ac.uk/research/groups/cell-and-molecular-sciences/soft-fruit-genetics/rubus/root-rot) If you go to that site, be aware that the chemical management described is not available to home gardeners, whether in the UK or the US.

I will also request a second opinion from a more experienced colleague. But, due to the coming holiday, be prepared for a several day delay before you receive a response.

This information is a summary submitted from my colleague. Please notice that his conclusions point to a cultural problem of some sort which has resulted in very dry soil and insufficient water to the plants. Additional factors may include fertilizer and/or construction of the bed and the material in it.

My colleague wrote: “I see an image of raspberry plants with lower leaves dried and brown and still attached to the canes. They do look like primocanes so we are going to assume these are not floricanes. Some leaves appear to have marginal necrosis and areas that are consistent with sunburn, too hot, not enough water, etc.. Plants are on raised beds and appear to be irrigated with one soaker hose. Hard to tell compass directions but the images seem like it is to the southeast (just a guess as I was wondering about that white fence and sun reflection but have ruled that out.). I also note that there is not a weed to be seen in the yard – well, in the image of the yard.

“Agree the soil looks dry and crumbly. The other image shows a primocane with green growth on top and senescing yellowing and necrotic leaves on the bottom.

“So there may be many issues from lack of nitrogen or some mobile element to irrigation troubles…. Can’t rule out herbicide trouble or even raised bed construction (may have been placed on top of a hard pan of some sort restricting drainage.

“For a root rot diagnosis I would want them to cut into the roots and root crown to see if we find the brick red color typical of Phytophthora. May not find it if there are that many fine roots.

“Plain lack of water explains all of it. It has been a very hot summer for plants.

“I am concerned about the phrase that the raspberries before had the same problem. Your suggestion of raising them in a different location is good.”

In addition to all the above, please review the information in this link as it may provide some useful insights:
“Growing Raspberries in Your Home Garden” http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/18936/ec1306.pdf