Maize Dwarf Mosaic Virus (Corn)

MDMV

Potyvirus

Corn leaf showing MDMV infection
Corn leaf showing MDMV infection. Photo courtesy of Clemson University. Licensed under CC BY 3.0.
MDMV is a virus that is carried and transmitted by 15 different species of aphids. It develops into a mottle/mosaic pattern on leaves, often resulting in slowed ear formation and development. This leads to yield loss in many areas that it is present.
MDMV is caused by various strains of a pathogen that is carried and transmitted by aphids. Aphids pick up and transmit the virus almost immediately through eating the plant's soft tissue. It can also be spread by rubbing infected leaves with non-infected leaves or by seed.
Symptoms of MDMV occur around 6 weeks after transmission of the virus. Depending on the strand of MDMV and the growth stage of the infected plant, the pattern of the diease mottled, mosaic, light green to yellow streaks, or blotches. Young infected plants will be stunted, and older plants will likely experience slowed ear development or become barren. Infected plants are more susceptible to other fungal infections like ear or stalk rot.
Corn Infected by MDMV
Light streaks indicating presence of MDMV in corn. Photo courtesy of Mary Ann Hansen. Licensed under CC BY 3.0.
MDMV may have a significant impact on yield depending on how extensive the infection is. Loss occurs through halting of ear development or production and stunting of plants. Damage can be severe if plants are infected at an early growth stage where aphids are severe. Some yield losses have been reported to be as high as 40 percent.
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.