Johnsongrass is a common carrier of this disease, and it ought to be removed from any surrounding areas in order to prevent aphids from being infected. It is also possible to delay planting until after aphid flights are over. Removing volunteer plants and graminaceous weed species will decrease the liklihood of the virus becoming an issue.
Use of insecticides and biological control methods will reduce aphid populations and chances of transmission. Higher levels of nitrogen in the soil will favor aphid reproduction, so it's important to limit excess application of nitrogen. 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.
There are a variety of resistant hybrids that can be used to prevent the infection of MDMV.