Arbutus: arbutus on Saturna

Discussion in 'Ericaceae (rhododendrons, arbutus, etc.)' started by Beth Bell, Aug 11, 2004.

  1. Beth Bell

    Beth Bell Member

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    Hello - I just spoke to someone on Hortline about our arbutus on Saturna. As suggested, attached are a number of photos of the tree. We are concerned that it's not looking that healthy, and would be grateful for an opinion from your arbutus expert about whether what we're seeing is the effects of the ongoing drought or something else, and if there's anything we could be doing to improve the health of the tree.

    Thank you so much for your help. As you can see, it's an incredible tree and we would be devastated if it were to fail.
     

    Attached Files:

  2. Douglas Justice

    Douglas Justice Active Member UBC Botanical Garden Forums Administrator Forums Moderator VCBF Cherry Scout Maple Society 10 Years

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    Your arbutus actually looks very happy. Dying twigs, yellowing, bug-eaten leaves and aborted fruit are not unusual from time to time, particularly under adverse environmental conditions. I've seen arbutus trees lose major scaffold branches over a period of a few years (initially, the leaves dropped, then the stems became blackened and shrunken), only to rebound later with new growth from the remaining stems.

    It is difficult to know what happens in the root zone of a naturally occuring Arbutus menziesii (arbutus or Pacific madrone). In many places in the Gulf Islands, the roots grow through gravel and into fissures in the underlying rock. Here, deep in the ground the conditions are cool, and moist enough to keep the roots alive (but note that arbutus are more or less dormant at this time of year). Excessive drought will cause root dieback and subsequent branch failure; however, it is extremely difficult to know what the cause of the localized drought might be. Construction activity, including the shattering of underlying bedrock, the installation of drainage or any significant change in the rooting environment can cause problems. Perhaps surprisingly to some people, summer irrigation can also cause root dieback (plants are not only dormant when the weather is hot, but also adapted to a highly oxygenated root environment).

    Other problems include a suite of fungal organisms that, under the right conditions (i.e., primarily under multiple environmental stresses and with the presence of a significant inoculum source) can become pathogenic. As such, these organisms contribute to "arbutus decline," a syndrome that was characterized (and studied extensively) in the native arbutus populations around Seattle. In general, however, arbutus decline appears to be a problem where landscape changes occur around older, strongly site-adapted specimens.

    Enjoy your beautiful arbutus.
     
  3. Beth Bell

    Beth Bell Member

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    Mr. Justice - Thank you so much for your reply. As you can imagine, we are quite relieved. If I could impose upon you with one further question: we are planning to build, beginning site excavation in October or November. One end of the foundation will come to within about 10 feet or so of the tree (and also of several large firs). What do you think of this? Is it really dangerous? Do you think we should get an arborist to come over and excavate the roots? The person doing the site preparation works with a very small excavator and is sensitive to our concerns, but nonetheless we could certainly engage an arborist as well if you thought this would be prudent.

    Thanks again.
     
  4. Douglas Justice

    Douglas Justice Active Member UBC Botanical Garden Forums Administrator Forums Moderator VCBF Cherry Scout Maple Society 10 Years

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    Hiring an arborist to check out the work site is a good idea, but consulting arborists, and those who pass themselves off as arborists, often differ considerably in their experience and expertise. While there are a number of excellent practitioners in the Victoria/Gulf Islands area, accreditation by the International Society of Arboriculture (i.e., "certified arborist" designation) is unfortunately no guarantee of professionalism (there are still arborists who recommend indiscriminate tree-topping). This situation is not limited to our area. I would recommend that you first talk with neighbours and friends in the area who have undertaken similar work to see if they would recommend a local person.

    Good luck. I hope you're enjoying our spectacular summer (you must know it's not always like this).
     

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