gents- Because of their attractiveness as food, seed crops of Oregon white oak are often decimated quickly (12). Larvae of the filbertworm (Melissopus latiferreanus) and the filbert weevil (Curculio occidentalis) damage crops even before acorns ripen (23). Maturing or ripe acorns are consumed by woodpeckers, pigeons, doves, jays, wood ducks, mice, chipmunks, squirrels, pocket gophers, woodrats, deer, bear, and other wildlife, as well as by domestic animals.
Wind, wet snow, and freezing rain damage Oregon white oak less than associated hardwoods, but in tests it showed only moderate resistance to cold. Dormant buds collected northwest of Corvallis, OR, withstood -15° C (5° F) and twigs -20° C (-40 F) without injury (55).
Large Oregon white oaks are obviously fire resistant; they have withstood annual or periodic fires for years. But small oaks may be killed or badly damaged by fire, as evidenced by the increased density and spread of oak stands since the advent of fire control.
More than 110 pathogens have been found on the leaves, twigs, trunk, or roots of Oregon white oak (59). Most are of minor consequence; many are saprophytes. Leaf-spot, mildew, and anthracnose fungi sometimes attack the foliage, but control methods have been suggested for only one-an anthracnose disease (Gnomonia quercina). In 1968, this fungus caused moderate to severe dying of leaves and possibly death of oak trees in southern Pierce County, WA (14). Premature browning of foliage is occasionally widespread in the Willamette Valley, but the causes and effects have received only incidental attention. The hairy mistletoe is common on Oregon white oak in Oregon and California, forming conspicuous, rounded growths in the upper crown. Its effect on growth and vigor of this host is undetermined. The white pocket root and butt rot (Polyporus dryophilus) and the shoestring root rot (Armillaria mellea) are probably the most damaging rots found in Oregon white oak. Its heartwood is generally very durable; stumps and even relatively small stems may remain intact for years.
Although Oregon white oak is host to hundreds of insect species (19), damage is usually not severe, and loss of trees to insect attack is uncommon. The western oak looper (Lambdina fiscellaria somniaria) is probably the most damaging insect on white oak from Oregon north to British Columbia. In some years, oaks over large areas in the Willamette Valley are defoliated (23). The damage is temporary since the trees leaf out the next year and outbreaks are not sustained. The western tent caterpillar (Malacosoma californicum) and the Pacific tent caterpillar (M. constrictum) are widely distributed defoliators with a preference for oaks. Several species of aphid, particularly Teberculatus columbiae, feed on the underside of oak leaves; the snowy tree cricket (Oecanthus fultoni) lives in open-grown oaks and associated species; and several leafrollers (Abebaea cervella and Pandemis cerasana) are found on Oregon white oak. Oregon white oak is the principal host for R. cerasana, an introduced leafroller causing sporadic defoliation that is now maintaining a relatively high population and slowly extending its range around Victoria, BC (17). Many gall wasps are found on oaks; those prominent on Oregon white oak include Andricus californicus, which forms large, persistent, applelike galls on twigs; Bassettia ligni, which causes seedlike galls under the bark of branches that often girdle and kill the branch; Besbicus mirabilis, which forms mottled, spherical galls on the underside of leaves; and Neuroterus saltatorius, which forms mustard-seed-like galls on lower leaf surfaces that drop in the fall and jump around like Mexican jumping beans caused by activity of the enclosed larvae (18,23).
Only incidental damage by animals has been noted on vegetative parts of Oregon white oak. Douglas squirrels and western gray squirrels sometimes debark small branches infested by gall wasp larvae (64). Damage is scattered and may involve as much as one-fourth of a tree's crown. Gophers and other burrowing animals, whi