Red Pine Pocket Mortality - Biology

Insect vectors including root collar weevil (Hylobius radicis), pales weevil (H. pales), red turpentine beetle (Dendroctonus valens), pitch-eating weevil (Pachylobius picivorus), and Hylastes porculus, feed on freshly cut stumps, the lower stem and roots of red pine, transmitting the fungus Leptographium terebrantis and L. procerum into the lower stem and root system.

Once established in the communal root system of a red pine plantation, Leptographium spreads to healthy trees via root connections. Trees infected with Leptographium are stressed by a decrease in water conduction and a decrease in the production of defensive compounds. These stressed trees continue to attract lower stem feeding beetles, particularly the red turpentine beetle. Bark beetles (Ips pini and I. grandicollis) are ultimately responsible for tree mortality.

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Leptographium sp. in a gallery created by the red turpentine beetle. Photo by Dr. Ken Raffa