Dr. Robyn Roberts
Field Crops Pathologist and CSU Assistant Professor Robyn.Roberts@colostate.edu*
970-491-8239; @RobynRobertsPhD (Twitter)
*Email is the best way to reach me
DISEASE OBSERVATIONS
We have gotten a few reports of mosaic virus symptoms, and samples from three different locations in Sedgwick county have tested positive for both Wheat streak mosaic virus (WSMV) and Triticum mosaic virus (TriMV) (Figures 1 and 2). This is a co-infection, so both viruses are present in the same leaf for all three samples. TriMV levels were relatively higher than WSMV, suggesting that the majority of the symptoms are likely caused by TriMV, and TriMV is always worse when WSMV is also present because WSMV ‘helps’ TriMV infect plants. This was also what we observed last year, and while there is resistance against WSMV, there unfortunately is no resistance against TriMV. However, it does seem that varieties that carry the wheat curl mite resistance, which vectors/spreads both WSMV and TriMV, are faring better against TriMV. Additionally, mite populations tend to be worse during drought years because the mites go to the plants to find water. This may partially explain why viruses are bad this year in addition to overall plant stress. My group will continue to monitor and test for viruses.