Five-year progress report on coast live oaks

16 11 2009

I have been reporting for some time on the progress of seven ill coast live oaks in Fairfax, CA first treated with fire mimicry in November of 2004 (see here, here, and here). These oaks have been under the care of my friend and colleague Leith Carstarphen of Ecologic Landscaping. Alan Mart has also contributed his time and expertise in caring for these oaks.

After five years two of the oaks have succumb to sudden oak death, though not without a period of improved canopy health before their demise (see Sudden oak death). Today I would like to present repeat photographs of the five remaining oaks taken just a few days ago. I am pleased with the results. Readers can judge for themselves. (Please excuse my ill-fated attempt in some of the photos to match exposure levels).

There is one particular oak, case study no. 20041129.8, which tells an interesting story. I first chose this oak as a control tree since it was not initially treated. For two years the health of this untreated oak showed little if any change, as can be seen in the photographs below. Then as is so often the case the owner decided to treat all of the oaks, including this one, and after three years the oak is now showing modest improvement with fire mimicry.

Another important point – while the originally diseased oaks remain infected with sudden oak death, the non-diseased oaks remain uninfected. This is consistent with many other case studies showing that fire mimicry treatments may be particularly effective at stopping the spread of sudden oak death.

In the above oak (case no. 20041129.2) there is a brownish tinge in the canopy of the tree in the recent photo (on right). This browning is the result of a heavy crop of acorns growing on the branches.




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