Blueberry Bushes turning brown

Asked June 6, 2018, 5:24 PM EDT

Good afternoon. We have an older patch of blueberries, about 100 bushes that the previous owners thought were 50+ years old. When we obtained the property in the fall, the bushes were nine feet tall in places, and about 5 feet across.

We pruned through the winter, but the job turned out to be larger than we anticipated, and some of our pruning went all the way into April. At that point we were not pruning for new growth but to simply be able to reach the top and walk through the rows.

As we began pruning the last of the bushes, we found on that had turned mostly brown since the spring came - whole branches a burnt red color, leaves and buds shriveled. Since then, about ten other bushes have adopted the same issue. Some bushes have only one or two branches affected, others are nearly all completely dead.

My first thought is that a fungus entered the plants when we pruned past dormancy, but I don't know if I'm sniffing down the correct trail with that theory. We found several old canes with powdery mold when pruning.

Can you help us diagnose the problem and find a solution? Thank you so much for any help you can give.

Marion County Oregon blueberries horticulture

3 Responses

Thanks for your question about the blueberry dieback you are experiencing. It isn't really possible to diagnose the problem just from the photo - the symptoms shown could have had any of several causes, including a couple of viruses, or verticillium wilt, or it could be collateral damage from the severe pruning. Your best bet is to take samples in to the Marion County Extension office (1320 Capitol St NE, Suite 110), including freshly-cut stems, and if possible stems that are just beginning to show symptoms, as well as completely dead ones. The MGs there will be able to examine your plant in detail, with a microscope if necessary, and should be able to diagnose the problem for you.
By the way, the old canes with mold are probably irrelevant - the mold may have started growing on them after they died. Nevertheless, you might want to bring one of those in too.

Thank you, I will take samples into them.

The older canes with mold are all alive. But perhaps that’s a separate issue.

It could be related or separate, but either way, yes, take some of them in as well.