Cork oak is native to SW Europe and NW Africa, and is widely grown in Spain and Portugal for cork production. Cork oak is gaining popularity in California landscapes, though no cork industry has developed in CA.
Culture for Cork Oak
Grows well in Mediterranean climates with moderate wet winters and hot dry summers. Does not tolerate saturated soils or heavy clay. At maturity, this evergreen reaches heights of 40-70-feet, with thick blue-green leaves and rough, deeply furrowed bark.
Concerns about Cork Oak
Open grown cork oak can develop co-dominant branches or leaders. Heavy clay or over-irrigation leads to Phytophthora root disease and bleeding canker. Cork oak is also susceptible to powdery mildew, scale insects, and defoliating caterpillars. Stressed cork oaks may also be attacked by bark beetles, leading to bleeding symptoms similar to Phytophthora infection. In the Los Angeles area, this tree is attacked by the Polyphagous shothole borer.
Management Practices for Cork Oak
Cork oak should be pruned to remove or subordinate co-dominant stems and branches. If powdery mildew is present or has been a problem in past years, treatments are effective when applied preventatively on new growth. Trees stressed by root damage, poor site conditions, or extreme drought should be treated preventatively against borer attack. In wet or heavy soils, soil treatments against Phytophthora are recommended.