Yield losses in fields where the disease is well established may be severe depending on the susceptibility of the corn hybrid being grown. Diagnosis of virus infected plants is difficult based on field symptoms. Samples of plants should be tested in the laboratory to confirm the presence of the virus. Symptoms Maize dwarf mosaic MDM symptoms vary with the corn hybrid and the stage of development of the plant at the time of infection. Early infection results in chlorotic spots or flecks that elongate in young leaves in the whorl.
Flecks merge into chlorotic streaks along the leaves.
These streaks form mosaic or mottled patterns and may turn to a general yellowing as the growing season progresses. Infected plants are predisposed to root rot and may be barren. Maize chlorotic dwarf MCD symptoms include yellowing of youngest leaves in the whorl and a distinct fine yellow striping, or vein clearing of the smallest veins visible between the larger veins. This chlorotic vein clearing of secondary veins is diagnostic for MCD and may be more readily observed on the undersides of infected leaves. The striping may not be seen in later stages of development due to leaf reddening and general yellowing of the plant.