May 17, 2014
Like a beloved grandma, an oak tree is quirky but wise. It asks for little yet gives tremendously.
One oak tree houses more than 700 insects and a multitude of birds and other critters. There are 20 native oaks in California, shading the hottest hillsides and edging the coast. If properly cared for, oaks can live hundreds of years.
Quickest way to change the balance of good versus bad pests in your neighborhood? Cut down an oak. The easiest way to kill a mature oak? Put a lawn under it.
Having a stately oak in your garden is a gift to be treasured. However, there are common misconceptions about what it means to care for an oak. Here's what your oak tree would tell you if it could talk.
- "Leave me alone." There's a reason why ancient oaks thrive in undisturbed areas. No one has fed or watered or pruned them. Don't be a busy body gardener to your oak.
- "I just need a trim." Prune judiciously and only during dry weather when open cut wounds are less susceptible to infection. Remove as little foliage as possible. Keep cuts small. Do not try to alter the natural shape. If you want something shaped like a palm tree, go get one.
- "My feet hurt." Protect roots from heavy foot traffic, parked cars and construction. Anything that compacts the soil or raises the grade is potentially harmful. This includes pavers and other hardscape surfaces. Every time an oak grove is turned into a housing development, you can be sure the trees will suffer (and sometimes die). That's because little regard is often given for oaks' root protection zone, which is the area between the trunk and the edge of the canopy. Really, it's that big. Leave the fallen leaves and apply a layer of mulch. Voila, you're done.
- "I'm not hungry." Feed your family, feed the neighborhood, feed the world, just don't feed your oak. If your oak looks sick, it's probably because of a disease related to an unfavorable environmental condition such as those listed above. Feeding your oak may stimulate excessive leaf growth and encourage pest problems. Improperly applied, it can injure roots or burn foliage.
- "I earned these wrinkles." You'd show a few signs of wear at age 100, too, so give your tree a break. Some pests and diseases can be unsightly but not harmful, such as the oakworm, which can practically defoliate a tree. Don't panic. Oaks are tougher than you think and will likely recover without treatment.
- "I'm not thirsty in summer." The only reason to plant a lawn under your oak is if you want to kill it. Oaks want it wet in winter and bone dry in summer. Period. Oak bark is not adapted to summer moisture, and wet summer roots are prime candidates for deadly diseases. Most oaks die within 10 years if irrigated in summer.
- "Call the doctor." The best person to give your tree a checkup is a licensed arborist with significant oak tree experience. Some of the true telltale signs of trouble are dead or decaying branches, oozing wounds on the trunk, yellowing foliage and reduced vigor from one year to the next. A good place to start if your tree looks sickly? The Master Gardener help desk at 473-4204 or via email at HelpDesk@marinmg.org.