Symptoms vary in severity depending on the different hybrids/varieties and the stage at which the plant is infected. The disease is characterized by the presence of numerous, minute yellow specks and streaks that run parallel to the veins on leaves. As they grow and coalesce, they produce long stripes, bands or blotches of chlorotic tissue, finally resulting in the death of the leaf. Plant have a stunted appearance, with short internodes. Male inflorescences are deformed, with short rachis and few spikelets. In particularly susceptible plants or in case of early infection, ears do not develop properly and there are fewer of them per plant.
The symptoms are caused by a virus (MCMV) that can be transmitted by several types of insects: leafhoppers, beetles and also probably some species of mites (Tetranychus spp.) and thrips (Frankliniella spp.). MCMV is generally introduced into new maize-growing regions via infected plant material. Once present, it is transmitted persistently to healthy maize plants by the feeding of the insects mentioned above. It can also overwinter in their larval stages when maize plants are not at hand. It is not thought to be seedborne. However transmission through mechanical wounds is possible. High temperature, plant stress and long periods of wet weather favor the development of the disease.
There is no direct control of diseases caused by viruses. To prevent the incidence of this virus, the best method is to use resistant varieties. Please check the database for the biological control of beetles, thrips or mite that can serve as vector for this virus.
Always consider an integrated approach with preventive measures and biological treatments if available. Viral diseases cannot be controlled directly with the application of chemical products. However, the insect vectors that carry the virus may be managed with insecticides.