Title: Fungi associated with stem cankers and coincidental scolytid beetles on declining hickory in the upper midwest

Author: Juzwik, Jennifer; Haugen, Linda; Park, Ji-Hyun; Moore, Melanie

Year: 2008

Publication: In: Jacobs, Douglass F.; Michler, Charles H., eds. 2008. Proceedings, 16th Central Hardwood Forest Conference; 2008 April 8-9; West Lafayette, IN. Gen. Tech. Rep. NRS-P-24. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station: 476-482.

Abstract: Higher than expected levels of hickory decline and mortality have recently been reported by Forest Health Monitoring, USDA Forest Service, on Carya spp. in Iowa, Maryland, Missouri, New York, Pennsylvania, and West Virginia. Widespread mortality of hickory has historically been attributed to outbreaks of the hickory bark beetle (Scolytus quadrispinosus) during extended periods of drought. Results of a preliminary survey conducted in Iowa, Minnesota, and Wisconsin during 2006 commonly found 1) a recently described fungus (Ceratocystis smalleyi) associated with bleeding spots and lesions on Carya cordiformis; 2) a fungus(Fusarium solani) with no known report of causing cankers on Carya species isolated from sunken, annual cankers; and 3) the fungi (Phomopsis spp.), which are commonly cited as the cause of Phomopsis stem and branch galls. We hypothesize that hickory mortality in these states is due to a decline complex of interacting predisposing, triggering, and contributing factors whose biotic agents are interchangeable.