Trees susceptible to MOB
In its native range in Europe, North Africa, and the Middle east, MOB attacks at least 12 species of oaks. In California, it has been found infesting three species of white oak: most commonly valley oak (Quercus lobata), to a lesser extent, blue oak (Quercus douglasii), and rarely Oregon white oak (Quercus garryana). In two instances, very limited attacks were found in distressed California black oaks (Quercus kelloggii) in areas with severe infestations.
Valley Oak | Blue Oak | Oregon White Oak | |
| Height | 12-30 m (40-100 ft) | 6-18 m (20-60 ft) | 12-27 m (40-90 ft) |
| Leaf shape | Green, sinuate (alternatively rounded notches and lobes), up to 10 cm (3.9 in) long and up to 6 cm (2.4 in) broad. | Blue-green tint leading to the tree's name. Leaves are deciduous, 3.8 cm (1.5 in) to 10.2 (4 in) long, and entirely or partially lobed. | Green, and oblong to obovate (wider toward the tip), typically 5 cm (2 in) to 15 cm (6 in) long. The leaf margins are deeply or shallowly lobed, with rounded lobes and smooth edges. |
| Bark | Light gray to brown, thick, deeply furrowed on mature trees. | Grayish, relatively scaly and thin. Click for image | Whitish-gray to light brown, with broad ridges and irregular furrows. |
| Acorns | Long narrow pointed, 3-6 cm (1.25-2.25 inches) | Slender to elliptical, 2-.5 cm (0.75-1.75 inches) | Oval or barrel-shaped, 2-3 cm (0.8-1.2 inches) |
Valley oak images
Blue oak images
Oregon white oak images
