Oak: California gallfly categories: Oak Oak Insects Ornamental trees Ornamentals revision date: 2022-11-25 04:31 “Oak apples” caused by California gallflyPhoto 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 twig gall […]
Oak: Jumping oak gall categories: Oak Oak Insects Ornamental trees Ornamentals revision date: 2022-11-25 04:29 Jumping oak galls on leaves caused by an insectPhoto 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 appear in […]
Oak: Leaf galls categories: Oak Oak Insects Ornamental trees Ornamentals revision date: 2022-11-25 03:59 Jumping oak galls on leaves caused by an insectPhoto 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 several forms, […]
Oak: Oak leaf phylloxera categories: Oak Oak Insects Ornamental trees Ornamentals revision date: 2022-11-25 03:53 Oak leaf phylloxera damagePhoto 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 is a yellowish orange homopteran […]
Oak: Oak ribbed casemaker categories: Oak Oak Insects Ornamental trees Ornamentals revision date: 2023-04-12 12:00 Oak ribbed casemakerPhoto 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 only the […]
Oak: Oak treehoppers categories: Oak Oak Insects Ornamental trees Ornamentals revision date: 2022-11-25 12:53 Oak treehoppersPhoto 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 are quite […]
Oak: Pit scale categories: Oak Oak Insects Ornamental trees Ornamentals revision date: 2023-04-04 12:00 Oak pit scalePhoto 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 the twig […]
Oak: Stem galls categories: Oak Oak Insects Ornamental trees Ornamentals revision date: 2022-11-25 12:39 Oak stem gallsPhoto 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 may be […]
Oak: Anthracnose categories: Oak Oak Diseases Ornamental trees Ornamentals revision date: 2022-11-25 12:33 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 a […]
Oak: Armillaria root rot categories: Oak Oak Diseases Ornamental trees Ornamentals revision date: 2022-11-25 12:24 White fungal mat of Armillaria root rot infecting trunkPhoto 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 of smaller-than-normal leaves, […]
Oak: Leaf scorch categories: Oak Oak Diseases Ornamental trees Ornamentals revision date: 2022-11-25 12:20 Oak leaf with leaf scorch symptomsPhoto by: B.M. Johnson Biology Leaf scorch has many possible causes. Plants that are under stress (such as from drought or heat) may not provide sufficient water to leaves, causing the edges to turn bronze, then […]
Oak: Mistletoe categories: Oak Oak Diseases Ornamental trees Ornamentals revision date: 2022-11-25 12:16 Oak mistletoe (a true mistletoe)Photo by: J.W. Pscheidt Biology Mistletoe is a parasitic plant which grows on the branches of a host tree. True mistletoe, found on oaks and a few other hardwood species, does not grow on conifers. It is spread […]
Oak: Western oak looper categories: Oak Oak Insects Ornamental trees Ornamentals revision date: 2023-04-12 12:00 Looper crawling on edge of rhododendron leafPhoto by: S.J. Collman Biology The Western oak looper feeds mainly on the foliage of the Oregon white (or Garry) oak (Quercus garryana). Mature larvae of the Western oak looper are about 1″ long […]
Oak: Sudden oak death categories: Oak Oak Diseases Ornamental trees Ornamentals revision date: 2022-11-25 12:00 P. ramorum symptoms on tanoak leavesPhoto by: M. Elliott Biology Sudden oak death (SOD) is the common name for a disease of oaks (Quercus spp.) and tanoak (Lithocarpus densiflorus) caused by Phytophthora ramorum, a previously unknown and exotic plant pathogen. […]