Plant Disease Management Handbook

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Note: Spruce spider mites can result in a similar symptom pattern on Dwarf Alberta Spruce. Time of symptom development can help diagnose the difference between mites (gets worse with time) or sun burn (all at once).

Hard to keep dwarf spruce trees green with dryland management during the heat wave of 2021. This is the southwest side of the tree.

Jay W. Pscheidt, 2021.

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Blackberry (Rubus spp.) - Stamen Blight

Note The disease is not common on raspberry here but has been described on raspberry in Europe.

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Peach (Prunus persica) - Wood Decay

Tree Wound Paints

Wood decay indicated bu dark colored wood which yielded multiple secondary fungi.

OSU Plant Clinic, 2022.

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Oak (Quercus spp.) - Ganoderma Root and Butt Rot

Ganoderma conks are perennial, woody and appear on the base of the tree or on trunk wounds. Conks are grey-to-brown on top, with a pure white underside (pore layer) that turns brown when scratched.

OSU Plant Clinic, 2025.

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Rhododendron - Cutting Rots

Poinsettia (Euphorbia pulcherrima) - Bacterial Stem Rot

This poor 'Ice Punch' poinsettia cutting had several pathogens isolated including Phytophthora sp., Pythium sp., and Thielaviopsis.

OSU Plant Clinic image, 2013.

Cause Cenangium ferruginosum, a fungus reported to be common in Washington on lodgepole pine. The disease is generally restricted to trees that have low vigor as a result of site or climatic conditions. The disease may appear serious and widespread the first year after a severe winter and then subside during the next growing season.

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Pine, White - White Pine Blister Rust