Oak: California gallfly Categories: Oak Oak Insects Ornamental trees Ornamentals Last review date: 2025-06-30 10:34 “Oak apples” caused by California gallfly Photo by: R.S. Byther Biology The gall of this cynipid wasp larvae is the largest and most conspicuous of the galls on oak, achieving a diameter of one to four inches. It is a […]
Oak: Jumping oak gall Categories: Oak Oak Insects Ornamental trees Ornamentals Last review date: 2025-06-30 10:35 Jumping oak galls on leaves caused by an insect Photo by: A.L. Antonelli Biology Jumping oak galls cause small yellow spots on the upper surface of infested leaves. On the underside of the leaves are tiny seedlike galls. These […]
Oak: Leaf galls Categories: Oak Oak Insects Ornamental trees Ornamentals Last review date: 2025-06-30 10:36 Jumping oak galls on leaves caused by an insect Photo by: A.L. Antonelli Biology Leaf galls are caused by the feeding of several species of oak gall wasp larvae. Typical galls are enlarged or swollen plant tissues. These may assume […]
Oak: Oak leaf phylloxera Categories: Oak Oak Insects Ornamental trees Ornamentals Last review date: 2025-06-30 10:40 Oak leaf phylloxera damage Photo by: A.L. Antonelli Biology The oak leaf phylloxera is a pest of growing importance in the Pacific Northwest. It’s believed to have come from Europe in the early 1960’s. It is a yellowish orange […]
Oak: Oak ribbed casemaker Categories: Oak Oak Insects Ornamental trees Ornamentals Last review date: 2025-06-30 10:41 Oak ribbed casemaker Photo by: A.L. Antonelli Biology Oak ribbed casemaker larvae mine and skeletonize leaf tissues. Young larvae feed inside leaves, chewing away tissues and leaving a linear mine. Older larvae feed on the underside of leaves, leaving […]
Oak: Oak treehoppers Categories: Oak Oak Insects Ornamental trees Ornamentals Last review date: 2025-06-30 10:42 Oak treehoppers Photo by: A.L. Antonelli Biology The oak treehopper belongs to a family of plant lice distantly related to aphids. However, they are fairly hard-bodied, and the adults bear a pointed hood on the back behind the head. They […]
Oak: Pit scale Categories: Oak Oak Insects Ornamental trees Ornamentals Last review date: 2025-06-30 10:43 Oak pit scale Photo by: A.L. Antonelli Biology Pit scales of oak may be brown, gold, or greenish in color. They feed on twigs and small branches, with young wood most commonly infested. Pit scale feeding causes the tissue of […]
Oak: Stem galls Categories: Oak Oak Insects Ornamental trees Ornamentals Last review date: 2025-06-30 10:44 Oak stem galls Photo by: A.L. Antonelli Biology Stem galls are caused by the feeding of several species of oak gall wasp larvae. Typical galls are enlarged or swollen. Galls associated with oak stems are often smooth and round, but […]
Oak: Anthracnose Categories: Oak Oak Diseases Ornamental trees Ornamentals Last review date: 2025-06-30 10:51 Biology Oak anthracnose is a fungal disease of leaves and twigs of many species of oak. Typical symptoms include the presence of small to large brown lesions on the leaves, usually along the midrib or main veins. Half or more of […]
Oak: Armillaria root rot Categories: Oak Oak Diseases Ornamental trees Ornamentals Last review date: 2025-06-30 10:55 White fungal mat of Armillaria root rot infecting trunk Photo by: C.R. Foss Biology Armillaria root rot is a fungal disease often found in newly cleared soils or soils which have been flooded. Above ground symptoms typically include production […]