| ield loss due to disease results from complex interactions between disease development and growth and development of plants. The effects of an Illinois isolate of wheat streak mosaic virus (WSMV) on yield of selected hard red spring wheat and soft red winter wheat cultivars were evaluated in three studies. In spring and fall of 1993 and 1994, twenty hard red spring wheat cultivars and fourteen soft winter wheat cultivars were planted in yield plots with three replications in a randomised complete block (RCB) design. Seedlings were mechanically inoculated at Feeke's growth stage 2 using an air brush. Controls were non-inoculated plots. Symptoms were rated every 7-8 days beginning one week after inoculation using a 0 to 5 scale, where 0 was no symptoms and 5 was severe stunting and chlorosis. The grain yield, 1,000 kernel weight and plant height were analyzed. There were significant differences among some cultivars for all the traits. Yield reductions in 1993 were greater than in 1994 which may have been caused by the differences in the environmental conditions. In the second study the response of three hard red spring wheat cultivars and four soft winter wheat cultivars when inoculated at different growth stages with WSMV were evaluated in yield plots in a RCB design with 3 replications. Seedlings were mechanically inoculated using an air brush at Feeke's growth stages of 2, 4, 6 and 8. Controls were noninoculated plots. Symptoms were rated as above. The response of the wheat cultivars to inoculation with WSMV at different growth stages was significant (Pr... |
