Arbutus unedo sudden death

Discussion in 'Outdoor Gardening in the Pacific Northwest' started by JavaJ, Apr 7, 2022.

  1. JavaJ

    JavaJ New Member

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    Hi there. I’m wondering if anyone might have some insight as to why my Arbutus Unedo died. It was in seemingly perfect health in December with flowers and fruit and glossy green leaves. In mid February I noticed the foliage was darkening. Within a month the tree was completely dead. It has been growing in the same spot for 10 years and has never shown any signs of disease. I have been trying to encourage it to grow in a better direction, so I have been pruning cautiously for a few seasons. I’m wondering if the extreme cold snap we had in Vancouver over Christmas might have done it in. Or is this some type of blight. Should I be concerned about replanting a new tree in this spot. Many thanks for any input.
     

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  2. Michael F

    Michael F Paragon of Plants Forums Moderator 10 Years

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    How cold did it get in your cold snap? It can tolerate temperatures down to about -10 to -15°C, but anything below that, and that's your likely answer.
     
  3. Margot

    Margot Generous Contributor 10 Years

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    It may be that your tree succumbed to the record -15.3C recorded in Vancouver on December 27, 2021 but A. unedo should be able to withstand colder temperatures than that. (Sunset Climate Zone 4 suggests -23C - 28C). Do you know of any other A. unedo in your vicinity that have died?

    Perhaps the heat dome we experienced at the end of June had something to do with it. Even though established Arbutus unedo are fairly drought tolerant, is it possible that lack of water might have led to this OR, if you watered it, is it possible that it got too much water? Excessive watering and/or poor drainage can lead to root rot fungal diseases.

    There is a mysterious disease killing A. unedo south of the border which may be responsible but I don't know if it has been found in BC. “The symptoms start with lesions forming in the bark near the base of the tree, a foot or two above the soil line. Sunken, dark cracks that turn charcoal gray." If you see these symptoms, read What’s killing the colorful strawberry tree? – Marin Independent Journal

    If and when you decide to plant another tree, it would be best to choose a different location just in case there may be any fungal spores in the soil. Also, it's very important to apply a thick mulch of wood chips in a generous circle under the tree (but not right up to the trunk). This helps mitigate temperature fluctuations and retain moisture in the soil - among other good things.
     
  4. Michael F

    Michael F Paragon of Plants Forums Moderator 10 Years

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    I doubt the heat dome would be responsible - the species grows in some very hot areas of Spain, and any symptoms related to the heat/drought last summer would have appeared much sooner (during, or very soon after, the event).

    Disease is certainly a worry. In particular, an ever increasing number of Phytophthora species are being spread around the world by human activity, and new hybrids evolving to attack new hosts when different Phytophthora species meet for the first time :'(
     
  5. JavaJ

    JavaJ New Member

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    It got down to -10 to -15 for a solid week. Very unusual for Vancouver. I thought maybe since it had been established for such a long time it may have been more tolerant. Poor thing:( thank you so much for your reply.
     
  6. JavaJ

    JavaJ New Member

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    Hi again and thank you for the insight. It is very strange what has happened with this tree. I went out and had a better inspection of the bark and leaves. I don’t think it is issue with the cankers on the bark as described in California. I did notice upon closer inspection done very small white spots (insects?fungus?) around the bottoms of the trunk and just few on the branches. Not extensive as I had to look very closely to notice them. It seems that would be to small an infestation of anything to kill the plant so suddenly. I’m leaning towards thinking the sub zero temps caused this as it was healthy looking in early December and gone by mid February. But it has lived through at least 10 winters and we have encounteredI’ve attached pics of the white spots in case it may give a clue.
     
    Last edited by a moderator: Apr 9, 2022

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