Maize dwarf mosaic virus (MDMV) and Sugarcane mosaic virus (SCMV)
Virus diseases spread by aphids

Nature of damage

• Aphids transmit the virus through feeding.
• Depending on time of infection, there may be severe stunting of the plant.
• Plants infected early may produce nubbins or be totally barren.

Signs

• Infected plants develop a distinct mosaic—irregularities in the distribution of normal green color—on the youngest leaf bases. Sometimes the mosaic appearance is enhanced by narrow chlorotic streaks extending parallel to the veins.
• Later on, the youngest leaves show a general chlorosis, and streaks are larger and more abundant.
• As plants approach maturity, the foliage can turn purple or purple-red.

Factors favoring development

• Disease incidence is highest where vector populations are high, a large number of infected plants are present, and susceptible varieties are cultivated.

Geographic distribution

• MDMV is most severe in the United States, though SCMV has been documented whereever maize and sugarcane are cultivated.
• In China, SCMV has been reported as seriously affecting maize production.

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