| White Pine Blister Rust |
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| Cronartium ribicola |
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Plant hosts
- Major hosts: Pinus (pines), Pinus koraiensis (fruit pine), Pinus lambertiana (big pine), Pinus monticola (western white pine), Pinus parviflora (Japanese white pine), Pinus parviflora var. pentaphylla, Pinus pumila (dwarf Siberian pine), Pinus strobus (eastern white pine), Ribes (currants), Ribes nigrum (blackcurrant)
- Minor hosts: Ribes alpinum (alpine current), Ribes americanum (American black currant), Ribes aureum (golden currant), Ribes bracteosum (stink currant), Ribes cereum (Wax currant), Ribes glandulosum (skunk currant), Ribes hirtellum (hairystem gooseberry), Ribes hudsonianum var. petiolare (western black currant), Ribes lacustre (swamp black currant), Ribes laxiflorum (trailing black currant), Ribes lobbii (Lobbs gooseberry), Ribes montigenum (mountain gooseberry), Ribes nevadense (Sierra currant), Ribes oxyacanthoides (northern gooseberry), Ribes roezlii (Sierra gooseberry), Ribes rubrum (red currant), Ribes sanguineum (flowering currant), Ribes speciosum (fuchsia-flowered gooseberry), Ribes triste (swamp red currant), Ribes uva-crispa (gooseberry)
- Wild hosts: Castilleja sp. (paintbrushes), Pedicularis sp. (lousewort)
To view larger image click on picture.
Image provided by Joseph O'Brien, USDA Forest Service.
Means of movement and dispersal
Plant parts liable to carry the pest in trade and transport:
- Bark: spores and hyphae are born internally. Spores and hyphae are invisible.
- Leaves: spores and hyphae are born internally and externally. Spores and hyphae are visible under light microscope.
- Seedlings and micropropagated plants: spores and hyphae are borne internally. Spores and hyphae are invisible.
- Stems: hyphae is born internally and are visible under light microscope.
Plant parts not known to carry the pest in trade and transport:
- Bulbs, tubers, corms and rhizomes.
- Fruits.
- Growing medium accompanying plants.
- Flowers.
- Roots.
- Seeds.
- Wood.
Symptoms
The first symptom is a yellow or red spot on infected needles in the spring. By fall, orange hyphae may be seen in the bark at the base of these needles. Dark lesions develop in this area and continue to develop into the characteristic diamond-shape cankers. Old cankers are rough and elongate structures that develop on trunks and branches, causing dieback or "flagging". Orange spore masses burst through the margins of the cankered bark (aeca). An abundant pitch flow usually accompanies canker formation. A branch or branch stub may be near the canker's center. Generally observed in the lower portion of the trees.
Return to the plant pathogen list .
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