Non-Peer ReviewedOrange wheat blossom midge, Sitodiplosis mosellana (Géhin), causes significant yield losses to
spring wheat in western Canada in severe infestations. To mitigate losses, midge-resistant wheat
varietal blends, consisting of cultivars carrying the Sm1 midge resistance gene and 10%
interspersed midge susceptible refuge, have been made available to farmers. To test their
performance relative to conventional midge-susceptible cultivars, four varietal blends were
grown during four consecutive years, at eight locations in the provinces of Manitoba
Saskatchewan and Alberta, in comparison to four conventional, midge-susceptible cultivars.
Midge damage was higher in 2007 and 2010 than in 2008 and 2009. In general, the varietal
blends, as a group, yielded more grain than the susceptible cultivars, especially when grown in
environments with high midge pressure (5.5 - 35% seed damage). In environments with low
midge pressure (0 – 2.6% seed damage), the varietal blend average yield advantage was smaller
but still significant, indicating that some of the varietal blends had additional superior attributes,
in addition to midge resistance
