Maize Dwarf Mosaic Virus (MDMV): maize dwarf mosaic is a virus disease that occurs over all the sorghum producing areas of Texas. Its ability to cause damage is dependent on the presence of an overwintering virus host (mainly Johnsongrass), aphid populations to facilitate virus transmission and the susceptibility of the hybrid being grown. Affected plants have mottled (light green blotchiness) terminal leaves. These alternate light- and darker-green areas in the leaf can be more easily seen when held between the viewer and a light source. Observers should always look at the newest leaves for the most severe symptoms. Highly susceptible hybrids are stunted with chlorotic symptoms in the upper leaves and suffer significant yield losses. Some hybrids produce a red leaf symptom when plants are infected and when night temperatures are below 55 degrees F. Use tolerant hybrids and control Johnsongrass in and around the field to manage this disease.
