Background and Rationale
Because of the emerald ash borer (EAB, Agrilus planipennis), Oregon ash (Fraxinus latifolia) is now listed as ‘near threatened’ on the International Union for Conservation of Nature (IUCN) red list. Oregon ash and other North American ash species are highly susceptible to EAB, an introduced insect pest. The devastation caused by EAB in eastern North America has led to the listing of five other ash species as being at risk of extinction by the IUCN. EAB has killed millions of ash trees in the eastern U.S., but some ash species seem to have limited resistance to the insect. Because of the recent introduction of EAB into Oregon, there is a strong need to develop an ash breeding program that can work toward breeding for genetic resistance to EAB. The expected impacts of EAB and more information on our project can be found in a recent video produced by OPB Oregon Field Guide: Can anything stop the Emerald ash borer beetle (https://www.youtube.com/watch?v=sYJ44_vh8iw)?

Approach
A breeding program for Oregon ash will require substantial funding and long-term commitment. Thus, our first step was to enlist collaborators. We now have more than 50 individuals from 25 organizations serving on our Steering Committee. Together, we set out to meet two immediate objectives. Our first objective is to collect ash seeds from hundreds to thousands of native ash trees to serve as a base breeding population. The second objective is to establish progeny test plantations of Oregon ash to test for resistance to the emerald ash borer and identify resistant genotypes. The progeny test plantations will (1) give us a jump-start toward measuring genetic resistance to EAB in the field, (2) lead to the development of deployment zones for Oregon ash based on climate adaptation, (3) serve as an open resource for other scientists studying EAB and the genetics of ash species, and (4) serve as a foundation for the Oregon ash breeding program. Our longer-term objectives are to identify genotypes genetically resistant to EAB, establish genetically resistant genotypes in seed orchards or cutting hedges (i.e., for vegetative propagation), and breed/hybridize resistant trees to further improve insect resistance, and make improved genotypes available to nurseries for producing trees for outplanting. These objectives will be mostly met using traditional breeding methods (Howe et al 2006). However, we will eventually incorporate genomic approaches as appropriate (Sniezko et al 2023).

References
Howe, G.T., Jayawickrama, K.J., Cherry, M.L., Johnson, G.R., and Wheeler, N.C. 2006. Breeding Douglas-fir. Pp. 245-353. Chapter in: Plant breeding reviews, v. 27, J. Janick (ed). John Wiley and Sons, Inc.

Sniezko, R.A.; Koch, J.; Liu, J.-J.; Romero-Severson, J. 2023. Will genomic information facilitate forest tree breeding for disease and pest resistance? Forests 14, 2382. https://doi.org/10.3390/f14122382