As noted during our May 11^th Field Day presentation in Davis, during the 2016-17 season darkening/purpling glumes (as depicted in Image 1) were widely observed in common spring wheat both within the UC Regional testing program and by growers and crop consultants around the San Joaquin and Sacramento Valleys. In addition, these symptoms appeared to have a genetic link because particular wheat varieties consistently displayed symptoms in multiple locations, while others displayed none.

There are multiple potential causes for darkened glumes, some pathogenic and some physiological. Cassandra Swett, the UC Cooperative...