Working with the help of a federal grant from the USDA Forest Service, the Oregon Department of Forestry (ODF) has been gathering seed of Oregon ash from throughout the state. The goal is to preserve its gene pool before a destructive pest arrives which may wipe out the tree.
“This is a first-of-its-kind effort in the long saga of invasive pests and diseases attacking North American trees,” said ODF’s Invasive Species Specialist Wyatt Williams. “By the time scientists are funded and able to start looking for resistance, a large part of the gene pool of the species being attacked has already been lost.”
Williams said Oregon is fortunate to be able to gather seeds representing the whole range of Oregon ash genes ahead of the arrival of emerald ash borer, which will devastate ash trees here as it has done across the country. That insect, originally from Asia, was found in Michigan in 2002. It has since spread to the Rocky Mountains of Colorado. Everywhere it invades, the insect kills almost all ash trees. Females lay their eggs on ash trees. The larvae then eat tunnels under the bark through the cambium layer. The tunnels make it impossible for the tree to move water and nutrients from the roots to the leaves and back, eventually killing it.
“We know from field tests back East that emerald ash borer will attack Oregon ash,” said Williams. “Although not an important timber species, Oregon ash withstands flooding, stabilizes banks against erosion and provides crucial habitat for wildlife. Losing it will greatly harm the ecology of wetlands and streamside forests.”
The USDA Forest Service is collaborating in the effort to save Oregon ash by storing the seed at its Dorena Genetic Resource Center in Cottage Grove. Richard Sniezko, PhD, said some of the seed will be put in long-term storage and some will be sent to field research sites in the Midwest already infested with emerald ash borer. Researchers there will plant Oregon ash to see if any of the seedlings show natural resistance to the pest. If they do, Sniezko said seeds from those same batches could be sown and the resulting seedlings used in restoration of natural areas.
“The hope is that we might be able to have some resistant trees already growing in the landscape by the time emerald ash borer gets to Oregon,” said Sniezko.
If emerald ash borer wipes out Oregon ash in the future and is then successfully controlled, the stored seeds could be used to reintroduce Oregon ash in all the places it once grew. Or if the pest becomes entrenched, as seems likely, then crosses could be made with the few resistant trees to build genetically diverse stocks of resistant trees.
“Since resistance is likely to be quite rare. there is a real danger that those few surviving trees won’t have the full range of genes a species has built up over hundreds of thousands or millions of years,” said Sniezko. “This effort is insurance against that kind of genetic loss.”
Williams said the most likely way the pest will arrive is through people bringing in firewood, unaware that it is from trees infested with emerald ash borer larvae. That is why he urges people not to transport firewood from one area to the next. “Buy it where you plan to burn it,” is the advice he gives.
A video explaining the campaign to save Oregon ash is debuting online as part of National Invasive Species Week Feb. 28-March 4. It can be viewed at Saving Oregon Ash.