MCDV is responsible for major crop losses that occured in the United States during the 1960s and 1970s, but has not been much of an issue in recent years. It is transmitted from Johnsongrass by leafhoppers
MCDV overwinters in stands of Johnsongrass and is carried over to crops through leafhoppers that feed on the plant. It is must be feeding persistently in order to aquire the virus, but transmission only takes seconds.
Visual diagnosis can be difficult, but vein banding is a very common sign of MCDV infection. Other symptoms include stunting of growth, leaf reddening/yellowing, leaf twisting/tearing, and clearing of small leaf veins. Leaves may develop a rough texter throughout as well. Vein chlorosis (banding) is the best way to tell if the plant is infected by MCDV. Often, the edges of the leaf redden before anything else.
MCDV damage depends largely on the presence of Johnsongrass, as it is the only perennial host of MCDV. In labs, corn losses have ranged from 5 to 91 percent in susceptible hybrids. Naturally, however, leafhoppers do not prefer corn as a food source.
The best way to avoid MCDV disease is to eradicate Johnsongrass near fields early in the season.
Apply herbicide to any surrounding Johnsongrass stands. It is best to avoid foliar insecticides in attempts to limit leafhoppers. A more effective strategy is to use seed treatment with systemic insecticides. Please contact your local plant pathologist to learn what is most effective in your area and how to use it best. Always read and follow all label instructions.