Hoping to add raspberries to your garden this year? Beware the dreaded phytopthora.
Climate change strikes again.
Cliff notes: to avoid this disease, plant “root rot” or “phytophtora” resistant cultivars. Ensure adequate drainage by planting on mounded soil amended with organic matter.
Raspberries are one of the very first plants I started with decades ago. I’ve transplanted them from the three different properties I’ve lived on since that time. I’ve always been able to harvest gobs of raspberries - enough to adequately stock my freezer.
Until they croaked.
What happened? A crazy, extremely cool and rainy June a few years ago. My raspberry garden flooded like I have never seen. And the raspberry canes that did not immediately die have since succumbed.
Since that time, I’ve seen more and more gardeners perplexed by sudden die off of their raspberries.
Phytopthora is also called “root rot” of raspberries. The disease is a fungus like organism that is at its worst on compacted soils and/or soils that don’t drain sufficiently.
Symptoms of root rot show up when the weather starts to warm up in the late spring with sudden wilting, leading the gardener to think there must be an issue with the plant not getting enough water. Of course, additional water will not solve the problem.
Climate change is causing some wacky weather patterns, one of which is extreme rain, so if you cherish your raspberries, it pays to guard yourself on this issue.
What can the hopeful raspberry grower do?
Plant resistant cultivars. Do your homework on cultivars you are considering. This publication by OSU shows some data collection on which cultivars are resistant to root rot or are known to be susceptible. Plant nurseries will often list this info as well - be sure to double check with other sources.
One issue I’ve found is that there is a huge variation in flavor in raspberries. I don’t know which rot resistant cultivars taste good. I will update here when my new plantings come to fruiting age. The publication listed above jots some notes about which have better flavor, but their tastes may differ from mine. It could be worth your time to seek out u-pick farms that have variety info and do some tasting. Near me, South Barlow Berries has all of their raspberry cultivars nicely labeled.
As of 3/2024 the OSU publication states that of the June-baring cultivars, Killarney is moderately resistant with excellent flavor, Cascade Dawn is very resistant with very good flavor, and Boyne is tolerant with good flavor. I am trailing Killarney and Cascade Dawn, will report back when I know more.
Do what you can to ensure adequate drainage. Root rot damage seems to be most severe on compacted soils that do not drain. Raise the soil up a few inches and add organic matter.
Have you seen this issue come up in your garden? Do you have experience with cultivars that are rot resistant and taste good? Drop me a comment below.
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