1)  Mites (on Sasa Bamboo and Skimmia)

• Stippling and yellowing of leaves are often indicative of the presence of mites.
• Feed by piercing underside of leaves and sucking chlorophyll out decreasing photosynthesis, reducing plant vigor and compromising the appearance.
• Mites are not insects; they are arachnids.

2)  Galls (on Willow and Rose)

• Abnormal plant growths caused by various organisms (insects, mites, fungi, etc.)
• Galls are formed by increased production of normal plant hormones as response to feeding, egg-laying or disease infiltration and are often not harmful to the plant.
• Galls can be on leaves, stems, twigs, buds, flowers and roots

3)  Blights (on Hazelnut and Cherry)

• Refers to a symptom affecting plants in response to infection by a pathogen.
• Blights come on rapidly and can cause complete chlorosis and browning of plant tissues such as leaves, branches and twigs; plant death is not uncommon.
• Aided by cool, moist conditions and limited air flow to plants…perfect for the Pacific Northwest!

4)  Phylloxera (on Oak)

• Microscopic, yellow sucking aphid relatives that feed on leaves and buds.
• Yellowish spots on leaves in spring turn to brown by summer and defoliate.
• Repeated defoliation abates photosynthesis and can lead to plant death.

5)  Armillaria root rots (shown on Bigleaf Maple, but many trees are susceptible)

• Fungus cause stunted leaves, chlorotic needles, dieback of twigs and branches and eventually death.
• Identified by white mats of fungal mycelium between the inner bark and wood and honey-brown mushrooms growing on or around the base of the tree.
• A big threat to the lumber industry as the wood is unsalvageable.