Seed-Transmitted Wheat Mosaic Virus in Sweet Corn in Utah

Abstract

Wheat mosaic virus (WMoV) (syn. High Plains virus) causes chlorotic streaks and mosaic on corn foliage, and it stunts ear development. In 2016 and 2017, plants in a sweet corn crop in northern Utah developed chlorotic streaking on leaves, and the plants remained stunted throughout the growing season but did not die after emergence. Symptoms ranged from bright yellow to nearly white streaks in stunted plants to faint chlorosis in plants that grew to normal height but only developed one ear or no ears. The symptoms resembled those caused by WMoV. Imaging using an unmanned aerial vehicle with a near-infrared camera showed that infected plants were scattered randomly across the field, a pattern often observed with seed-transmitted pathogen. All five symptomatic plants tested positive for WMoV. To confirm that no other virus was present, two samples of symptomatic plants were sent to a commercial laboratory, where they were screened for 11 viruses. They only tested positive for WMoV. In greenhouse grow-out tests, 83% of the seed germinated, and six plants developed symptoms in the first 5 weeks after emergence. The symptomatic seedlings were tested for WMoV, confirming infection. This study confirmed WMoV can be seed transmitted under field conditions.