Is it okay to prune coast live oaks in the winter if there is no SOD inoculum in the area? Are there other pests that are active in the winter that are of concern?

Although there may be few insects flying in the winter, the wet winter season (actually fall through spring) is a prime time for production of fruiting bodies by many wood decay fungi. The combination of fresh pruning wounds (especially large wounds), high spore densities of wood decay fungi, and moist conditions (favoring spore germination) can […]

I’m worried that my oak is drought stressed. How can I tell, and how much (if any) water should I apply?

Detailed information on “Watering Guidelines” can be found at

I have insect larvae in my oak acorns, what do to?

The Filbert weevil (Curculio occidentis) and Filbertworm (Curculio occidentis) are two common pests of oak acorns. The larvae of these insects live and feed in the acorn and can cause significant loses. There are currently no effective methods for control of these pests. Insect damaged acorns may also get secondary bacterial infections that cause drippy […]

What can I plant under my oaks?

As a general rule, avoid planting under the canopy of oak trees. It is recommended that you remove non-native plants from under oaks but avoid disturbing the soil or drainage patterns in the process. If you need to plant something, choose species that require similar soil types and watering. Avoid azaleas and rhododendrons as they […]

California Native Oaks

There are a number of common oak species in California including both tree species and shrub species. Trees species: Black Oak (Quercus kelloggii) Found in hilly regions between 2,000 and 6,000 feet. Typically associated with conifers and pines, firs, or incense cedars. Blue Oak (Quercus douglasii) Found in the hot, dry interior foothills. Generally found […]

What’s the Gold Spotted Oak Borer?

The GSOB is a destructive insect pest that is decimating some oak species mostly in Southern California. It has been found infesting coast live oaks (Quercus agrifolia), California black oaks (Q. kelloggii) and canyon live oaks (Q. chrysolepis). It attacks the limbs of mature oak trees feeding in the conductive tissues and sapwood. Unfortunately the […]

How many kinds of oaks are there in California?

There are a number of common oak species in California including both tree and shrub species. See our CA Native Oaks post for detailed information.  Illustration by Michael Lee – Link to his beautiful poster of the Native Oaks of California

Should I water my oak trees during the drought?

In general, healthy live oak trees are able to survive the dry seasons and extended droughts we experience in California. In most circumstances it is not necessary to water mature established live oak trees. Shallow watering can in fact cause additional problems. Over watering or improper watering of oak trees may promote the growth of […]