Ask the Steward
Question: All the Ash trees in my woods died, but new seedlings are growing. Will they survive?
Answer: The Emerald Ash Borer has now spread to every county in Indiana and has left millions of ash trees dead in its wake. Yet there has been a very small percentage of ash that have escaped this killing wave. Whether they are resistant to the emerald ash borer (EAB) or just lucky misses is yet to be determined. In some cases the survivors have been vigorous, fast growing younger trees that may have been able to heal over EAB larval galleries. Those same trees at an older, less vigorous
Adult EAB leave D-shaped exit hole in the bark of ash trees when they emerge in the spring. (credit: Kenneth R. Law, USDA APHIS PPQ, Bugwood.org) condition may not survive another attack. A second hope for long-term survival of the ash species is the new crop of ash trees that have sprouted up from seeds shed by mature ash trees before their death. As these trees increase in size and abundance and reach a critical carrying capacity a new round of EAB is anticipated to again knock out many of the new and missed ash from the last killing wave. It is hoped that natural controlling agents such as EAB parasites and Ash resistance will be manifested on the landscape and increase survival rates over time. This may take several regeneration cycles and many decades to balance out. Will your young new trees survive? Hard to tell—but, there is a glimmer of hope in the long run for the ash species. Landowners with large surviving ash in their woodlands after the passing of the 1st killing wave are encouraged to retain those trees. 
Feeding galleries caused by EAB larva. (credit: Michigan Department of Agriculture, Bugwood.org) In fact DNR would like to know locations of such trees for possible inclusion in Tree Improvement efforts of the USDA Forest Service. Visit www.in.gov/dnr/entomolo/3443.htm
Question: Where does the phrase ‘knock on wood’ come from?
Answer: This idiom has been around for centuries in one form or another, and since the early 1900’s in modern America. As the story goes it may have originated through early pagan beliefs that trees and wood contained spirits or gods that could hear your talk and effect your luck. By knocking on trees you could let the spirits know your presence. Or, such knocking made your speech undiscernible to the spirits. The phrase has variations almost worldwide. In Australia, they use the phrase ‘touch wood’. In Egypt it’s ‘hold the wood’. Today we continue the long tradition and use the phrase in fun to acknowledge good luck or ward off bad luck, while often physically knocking wood at the same time. At least that’s the way I do it and hear knocking three times brings best luck. Knock-knock-knock!
Dan Ernst is an Assistant State Forester with the Indiana Division of Forestry. He oversees the state forests in Indiana and has authored the “Ask the Steward” column for years. Have a question for the column? Email Dan at dernst@dnr.in.gov.