Submergence of black ash logs to control emerald ash borer and preserve wood for American Indian basketmaking

Indigenous artisans in the Great Lakes region rely on the ring-porous property of black ash Fraxinus nigraMarshall (Oleaceae), which allows annual layers of xylem to be easily separated to make baskets that are important economic resources and vessels of culture. The emerald ash borer Agrilus planipennisFairmaire (Coleoptera: Buprestidae) is threatening North America's ash resource, including black ash and this centuries-old art form, resulting in grave concern about the availability of black ash trees for basketmaking and about movement of black ash (along with A. planipennis) from areas where it is cut to lands where it is pounded and split to make baskets. We evaluated the traditional practice of storing black ash logs submerged in water as a possible method for killing within-tree life stages of A. planipennis at the same time as preserving the wood's value for basketmaking. Black ash trees infested with overwintering A. planipennis larvae were felled and cut into 60-cm bolts in 2010 and in 2011. These were submerged in a river for different lengths of time and, after treatment, placed into rearing tubes to determine survival and adult emergence, or dissected within 24h to determine larval mortality, and then pounded and peeled into splints to assess colour and pliability. In 2010, all A. planipennis larvae had died and no adults emerged from logs submerged in spring for 10weeks or longer, whereas some larvae survived and adults emerged from logs submerged for up to 9weeks. In 2011, submergence for 18weeks during winter or 14weeks in spring resulted in complete mortality of A. planipennis larvae and no emergence of adults at the same time as still preserving wood quality for basketmaking.