ARS | Publication request: Differences in susceptibility to onion smut (Urocystis cepulae) among onion lines in the National Germplasm Collection

Submitted to: National Allium Research Conference
Publication Type: Abstract Only
Publication Acceptance Date: November 1, 2006
Publication Date: December 7, 2006
Repository URL: http://vic.tamu.edu/narc/oralabstracts.htm
Citation: McDonald, M., Havey, M.J. 2006. Differences in susceptibility to onion smut (Urocystis cepulae) among onion lines in the National Germplasm Collection [abstract]. National Allium Research Conference. Available: http://vic.tamu.edu/narc/oralabstracts.htm.

Technical Abstract: Onion smut (Urocystis cepulae Frost) is endemic in many onion –growing regions of northeastern North America and can cause losses of up to 80 percent of plant stand if no fungicides are applied to the crop. Onion lines from the National Germplasm Collection in Geneva, New York were screened for relative susceptibility to onion smut in greenhouse trials. A total of 281 lines were evaluated in four groups. Lines in each group were compared to cultivar "Millennium”. Onions were seeded in 200 cell trays filled with muck soil that was naturally infested with the onion smut pathogen. Trays were incubated at 12- 15 C to provide optimum conditions for infection. Once the seedlings emerged, trays were moved to a greenhouse. One hundred onions per replicate were assessed at the first true leaf stage and another 100 onions per replicate were assessed at the 3-5 leaf stage. Significant differences in onion smut incidence were found in each assessment, although most lines were not significantly different from Millennium, which was relatively susceptible to smut infection. Some of the most resistant lines were Allium fistulosum. Cultivars such as Nasik, Hamlet, Gala and Sunset Red appeared to be highly susceptible to smut infection. Lines that were highly susceptible or resistant will be reassessed to confirm reaction to smut.