Quercus engelmanii | Coastal Southern California
That same tolerance/preference for summer irrigation appears to help Engelman Oak make a surprisingly good nursery tree. It is wise to choose acorns from only the most vigorous and attractive mother trees. In all trees assessed both in the San Francisco Bay Area and locations throughout southern California, there is little or no powdery mildew to be seen. From extensive observation, it is likely that Engelman Oak will remain largely or entirely mildew-free, even in such high mildew locations as downtown San Francisco.