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ARS Home » Northeast Area » Washington, D.C. » National Arboretum » Floral and Nursery Plants Research » Research » Publications at this Location » Publication #345596

Title: Challenge inoculations to test for Dutch elm disease tolerance: a summary of Methods used by various researchers

item HAUGEN, LINDA - Forest Service (FS)
item BEIER, GARRETT - University Of Minnesota
item Bentz, Susan
item GURIES, RAYMOND - University Of Wisconsin
item SLAVICEK, JAMES - Forest Service (FS)

Submitted to: Forest Service Meeting
Publication Type: Proceedings
Publication Acceptance Date: 9/22/2017
Publication Date: 9/26/2017
Citation: Haugen, L.M., Beier, G.L., Bentz, S.E., Guries, R.P., Slavicek, J.M. 2017. Challenge inoculations to test for Dutch elm disease tolerance: a summary of Methods used by various researchers. Forest Service Meeting.

Interpretive Summary: Over the decades, many researchers have used a variety of methods to challenge elm plant material with the fungus that causes Dutch elm disease (DED) for the purpose of understanding the development of the disease in elms and to breed or select tolerant trees. Scientists from ARS, the Forest Service and Universities participated in a panel discussion at a workshop in October 2016. Detailed information was shared about standard experimental methods used in conducting DED research and some of the complications and benefits associated with each. Participants noted many factors that influence the response of test trees to inoculation and interpretation of results such as plant vigor, age, inoculation timing and source, and amount and delivery method of the fungal inoculum. Improved challenge methodology will enable better comparison and understanding of outcomes of DED testing in differing locations and facilitate the identification of resistant elms.

Technical Abstract: A variety of methods have been used by different research groups to “challenge” inoculate American elms (Ulmus americana) with the purpose of determining whether some clones may be resistant to the Dutch elm disease fungus. The methods used by seven research groups are described, along with observations on complications and benefits associated with each. The response of test trees to challenge is affected by many factors, including the age of parent material, size/maturity of test material, vigor of the plant being inoculated, portion of the plant inoculated, season/time of year, source of inoculum, amount of inoculum, and method of delivery. The testing goal must be kept in mind when choosing methods, and the details of what methods were used must be described when reporting results. Inclusion of susceptible and resistant controls is critically important, as it allows calibration of response between different studies.