Rhododendron: Tissue proliferation categories: Ornamentals Rhododendron Rhododendron Diseases Shrubs revision date: 2022-12-04 12:00 Rhododendron tissue proliferationPhoto by: R.S. Byther Biology There is no known cause of tissue proliferation, but it is currently believed to be a genetic abnormality. A swollen area or gall develops at the base of the trunk or (more rarely) on a […]
Rhododendron: Root weevils categories: Ornamentals Rhododendron Rhododendron Insects Shrubs revision date: 2023-04-04 12:00 Root weevil damage on rhododendron leavesPhoto by: A.L. Antonelli Biology Several species of weevils feed on rhododendrons. Characteristic damage includes notching of leaf edges by adults and minor to severe root and bark damage by larvae. Occasionally the larvae girdle the trunk […]
Viburnum: Bacterial blight (Leaf spot) categories: Ornamentals Shrubs Viburnum Viburnum Diseases revision date: 2022-12-04 12:00 Viburnum bacterial blight (leaf spot)Photo by: R.S. Byther Biology Bacterial blight of viburnum primarily affects leaves and occasionally stems. Spots on leaves first appear as brown, watersoaked areas which may be round, irregular, or angular in outline. Developing leaves may […]
Viburnum: Leaf spot categories: Ornamentals Shrubs Viburnum Viburnum Diseases revision date: 2022-12-04 12:00 Viburnum leaf spotPhoto by: J.R. Glass Biology Various fungi cause leaf spot symptoms on viburnum. The spots are typically necrotic brown spots of varying sizes. At least one bacterial leaf spot is also common. Management Options Use Integrated Pest Management (IPM) for […]
Viburnum: Powdery mildew categories: Ornamentals Shrubs Viburnum Viburnum Diseases revision date: 2022-12-04 12:00 Powdery mildew on viburnum leafPhoto by: B.M. Johnson Biology Powdery mildew of viburnum is a fungal disease which primarily affects young leaves and shoots. Affected plant tissues develop a powdery white growth of fungal mycelia. The fungus can be found on either […]
Viburnum: Ramorum leaf and shoot blight (Sudden oak death) categories: Ornamentals Shrubs Viburnum Viburnum Diseases revision date: 2022-12-04 12:00 P. ramorum leaf tip necrosis symptom on viburnumPhoto by: M. Elliott Biology Ramorum leaf blight is caused by Phytophthora ramorum, the same organism that causes sudden oak death (SOD). In Washington, most cases have been found […]
Viburnum: Shoot blight (Gray mold) categories: Ornamentals Shrubs Viburnum Viburnum Diseases revision date: 2022-12-04 12:00 Viburnum Botrytis stem rotPhoto by: R.S. Byther Biology Shoot blight of viburnum is caused by Botrytis cinerea, a fungus commonly found on ornamentals, greenhouse plants and flowers, vegetables, and small fruits. Viburnums develop gray to brown spots along the leaf […]
Viburnum: Bean aphids categories: Ornamentals Shrubs Viburnum Viburnum Insects revision date: 2024-05-08 02:50 Bean aphid on leafK. Grey Biology Bean aphids are soft-bodied dark green to black insects commonly found on the undersides of leaves and on new growth. They often occur in dense colonies. Heavy aphid feeding may distort shoot tips and leaves, and […]
Viburnum: Root weevils categories: Ornamentals Shrubs Viburnum Viburnum Insects revision date: 2023-04-04 12:00 Root weevil damage on viburnumPhoto by: A.L. Antonelli Biology Root weevil larvae feed on the roots and bark of plants near the crown. The white grubs are found in the soil around the roots. Heavy feeding by root weevil larvae can cause […]
Viburnum: Viburnum leaf beetle categories: Ornamentals Shrubs Viburnum Viburnum Insects revision date: 2022-12-04 12:00 Viburnum leaf beetle larvae and damagePhoto by: T. Murray Biology Viburnum leaf beetles overwinter as eggs on the previous year’s new stems. Larvae hatch in spring and begin to feed on the new viburnum leaves. Larvae are pale yellow to pale […]
Skimmia: Spider mites categories: Ornamentals Shrubs Skimmia Skimmia Insects revision date: 2024-04-08 11:46 Citrus red mite damage on skimmiaPhoto by: R.S. Byther Biology Spider mites vary in color from green to reddish to brown. They are extremely small and may be barely visible to the naked eye. Mites are commonly found on the underside of […]
Pyracantha: Scab categories: Ornamentals Pyracantha Pyracantha Diseases Shrubs revision date: 2022-12-05 12:00 Pyracantha scab on leavesPhoto by: R.S. Byther Biology Pyracantha scab is caused by a fungus that overwinters in infected leaves, twigs, and berries. Young leaves and berries are most susceptible to infection. Olive green to black spots develop on leaves, twigs and fruit. […]
Pieris (Andromeda): Leaf spot categories: Ornamentals Pieris (Andromeda) Pieris (Andromeda) Diseases Shrubs revision date: 2022-12-03 12:00 Biology Leaf spot of andromeda is a fungal disease causing necrotic (dead) spots on the leaves. Spots are circular or angular in outline, and typically are red to brown, sometimes with silvery-gray centers. Fruiting structures of the fungus may […]
Pieris (Andromeda): Ramorum leaf and shoot blight (Sudden oak death) categories: Ornamentals Pieris (Andromeda) Pieris (Andromeda) Diseases Shrubs revision date: 2022-12-03 12:00 P. ramorum symptoms on Pieris leavesPhoto by: M. Elliott Biology Ramorum leaf blight is caused by Phytophthora ramorum, the same organism that causes sudden oak death (SOD). In Washington, most cases have been […]
Pieris (Andromeda): Root rot & dieback categories: Ornamentals Pieris (Andromeda) Pieris (Andromeda) Diseases Shrubs revision date: 2022-12-03 12:00 Pieris root rot and diebackPhoto by: J.W. Pscheidt Biology Root rot and dieback of andromeda is caused by Phytophthora, a fungus which affects many ornamentals. Typically, plants appear unhealthy, with wilted or discolored leaves that may be […]
Pieris (Andromeda): Black vine weevil categories: Ornamentals Pieris (Andromeda) Pieris (Andromeda) Insects Shrubs revision date: 2023-04-04 12:00 Black vine weevil adult and leaf damagePhoto by: A.L. Antonelli Biology Characteristic damage by black vine weevils includes irregular, ragged notching of leaf margins by adults and minor to severe root and bark damage by larvae. The adult […]
Photinia: Leaf spot (Diplocarpon) categories: Ornamentals Photinia Photinia Diseases Shrubs revision date: 2022-12-03 12:00 Photinia leaf spots and twig cankersPhoto by: J. Berger, bugwood.org Biology Fungal leaf spot of photinia is characterized by the presence of red to purple spots on the leaves. The spots are small at first, but soon enlarge and develop brown […]
Photinia: Physiological leaf spot categories: Ornamentals Photinia Photinia Diseases Shrubs revision date: 2022-12-03 12:00 Photinia physiological leaf spotPhoto by: R.S. Byther Biology Physiological leaf spot occurs on Photinia in western Washington. The symptoms resemble those of early fungal leaf spot infections. Small red to purple spots appear on the leaves, but do not develop the […]
Photinia: Powdery mildew categories: Ornamentals Photinia Photinia Diseases Shrubs revision date: 2023-02-09 12:00 Powdery mildew on photinia causing leaf curling and necrosisPhoto by: R.S. Byther Biology Powdery mildew is a fungal disease found on leaves and shoots of photinia. Characteristic patches of gray-white, powdery fungus are found in thick mats on the upper and lower […]
Photinia: Aphids categories: Ornamentals Photinia Photinia Insects Shrubs revision date: 2024-04-08 11:46 Aphid colony on leafPhoto by: A.L. Antonelli Biology Aphids on photinia are variously colored, from yellowish or greenish to black. They are soft-bodied insects less than 1/8″ long. Aphids often feed in large groups and typically are found on new growth, including both […]