Native Oaks of the Mountain
Of all the plants on the mountain our native oaks are the signature species of the region. They are as tough as trees get, but they are struggling with drought and climate change. What they need right now is water. If you have water to irrigate them, a soaker hose around the drip line for a few hours would be most beneficial. Their roots are not as deep as you would think.
Quercus Agrifolia, our native oak on the mountain, does have some other needs. They do not like the grade changed around them. No earth should be added or removed inside of the drip line. No more than 25 % of the branches should be pruned at one time, and the tree needs time to recover from pruning. When bark is exposed after pruning the tree’s response is to send out new growth to cover it up. This protects the tree from the sun’s drying and heating effect. They also like to have their branches reach all around them and down to the ground. Where this is not possible they should have as much of the lateral branches as can be left. The crown should be as full as possible as well.
They like their dead leaves and branches to remain as mulch. For fire safety this can be removed to a certain extent, but a few inches of mulch is important to protect the roots.
Borers and twig girdlers have been having a field day of late, but there is really not much we can do about it except irrigate to increase their resistance to pests. The trees can ooze sap to smother the little buggers if they have the extra moisture. Pruning the dead branches should be done judiciously to prevent overpruning.
If you would like advice from an expert arborist with long experience you can call Bill Spiewak at 805-331-4075. He is a very friendly expert on oaks. A wonderful book, Oaks of California, put out by our local Cachuma Press is a source of information with great photos that anyone with oak trees on their property will enjoy.
I would appreciate hearing of any other ideas you know of to help us adapt to what could be our new water reality. You can reach me at firstname.lastname@example.org
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