prepared by: Dr. Jochum Wiersma, Small Grains Specialist at University of Minnesota Although not nearly as heart-wrenching as the novel 'The Color Purple ', Memorial Day weekend is often the time that the color yellow is a cause for concern in spring wheat, barley, and oats. This year is no exception. The cause in this time doesn't appear to early-season tan spot just yet but more so heat canker. The hot and windy weather this past weekend were ideal conditions to cause this physiological phenomenon. More details about early season yellowing in general and heat canker specifically can be found here and here .