Abstract
Several North American walnut species (
Juglans spp.) are threatened by thousand cankers disease which is caused by the walnut twig beetle (
Pityophthorus juglandis Blackman) and its associated fungal plant pathogen,
Geosmithia morbida M. Kolarý´k, E. Freeland, C. Utley and N. Tisserat sp. nov. Spread of this disease may occur via movement of infested black walnut (
Juglans nigra L.) wood. This study evaluated the ability of P.
juglandis to colonize J.
nigra wood previously treated with various phytosanitation methods. Steam-heated and methyl bromide-fumigated J.
nigra logs, as well as kiln-dried natural wane J.
nigra lumber (with and without bark) were subsequently exposed to P.
juglandis colonization pressure in two exposure scenarios. Following a pheromone-mediated, high-pressure scenario in the canopy of infested trees, beetles readily colonized the bark of steam-heated and methyl bromide fumigated logs, and were also recovered from kiln-dried lumber on which a thin strip of bark was retained. In the simulated lumberyard exposure experiment, during which samples were exposed to lower P.
juglandis populations, beetles were again recovered from bark-on steam-heated logs, but were not recovered from kiln-dried bark-on lumber. These data suggest logs and bark-on lumber treated with phytosanitation methods should not be subsequently exposed to P.
juglandis populations. Further beetle exclusion efforts for phytosanitized, bark-on walnut wood products transported out of quarantined areas may be necessary to ensure that these products do not serve as a pathway for the spread of P.
juglandis and thousand cankers disease.
Keywords
walnut twig beetle,
forest product,
quarantine treatment,
thousand cankers disease,
bark beetle
Citation
Audley, J.; Mayfield III, A. E.; Myers, S. W.; Taylor, A.; Klingeman, W. E. 2015. Phytosanitation Methods Influence Posttreatment Colonization of
Juglans nigra Logs by
Pityophthorus juglandis (Coleoptera: Curculionidae: Scolytinae) . Journal of Economic Entomology: 1-11. 11 p.