PT  - JOURNAL ARTICLE
AU  - Wyka, Stephen A.
AU  - Doccola, Joseph J.
AU  - Strom, Brian L.
AU  - Smith, Sheri L.
AU  - McPherson, Douglas W.
AU  - Aćimović, Srđan G.
AU  - Klepzig, Kier D.
TI  - Effects of <em>Grosmannia clavigera</em> and <em>Leptographium longiclavatum</em> on Western White Pine Seedlings and the Fungicidal Activity of Alamo<sup>®</sup>, Arbotect<sup>®</sup>, and TREE-äge<sup>®</sup>
AID  - 10.48044/jauf.2016.007
DP  - 2016 Mar 01
TA  - Arboriculture & Urban Forestry (AUF)
PG  - 84--94
VI  - 42
IP  - 2
4099  - http://auf.isa-arbor.com/content/42/2/84.short
4100  - http://auf.isa-arbor.com/content/42/2/84.full
AB  - Bark beetles carry a number of associated organisms that are transferred to the host tree upon attack that are thought to play a role in tree decline. To assess the pathogenicity to western white pine (WWP; Pinus monticola) of fungi carried by the mountain pine beetle (MPB; Dendroctonus ponderosae), and to evaluate the potential for systemic prophylactic treatments for reducing fungal impacts, experiments were conducted with WWP seedlings to meet three objectives: 1) evaluate pathogenicity of two MPB-associated blue-stain fungi; 2) evaluate phytotoxicity of tree injection products; 3) evaluate the anti-fungal activity of tree injection products, in vitro and in vivo, toward the associated blue-staining fungi. To evaluate pathogenicity, seedlings were inoculated with Grosmannia clavigera or Leptographium longiclavatum, common fungal associates of MPB. Seedling mortality at four months after inoculation was 50% with L. longiclavatum and 90% with G. clavigera, both significantly higher than controls and thereby demonstrating pathogenicity. Phytotoxic effects of TREE-äge®, Alamo®, and Arbotect® were evaluated by stem injection; no phytotoxic effects were observed. Anti-fungal properties of the same three products were evaluated in vitro against G. clavigera, where Alamo was most active. Co-inoculation of G. clavigera and L. longiclavatum into seedlings after a stem injection of Alamo showed significantly less mortality and lesion formation than either species alone. Results support the hypothesis that MPB blue-stain associates, particularly G. clavigera, promote death of WWP when attacked by MPB. These findings suggest that the administration of a fungicide with insecticide for tree protection against bark beetles may be advantageous.