Corn Viruses

Maize Chlorotic Dwarf Virus, Maize Dwarf Mosaic Virus, and Maize White Line Mosaic Viruses.

Maize dwarf mosaic virus [Credit: Mary Ann Hansen, Virginia Polytechnic Institute and State University, Bugwood.org]

Host Plants:

In the wild: Some grassy weeds
On Crops: Sweetcorn and maize

Where Found:

Worldwide, wherever sweetcorn or maize is grown

Description:

When sweetcorn plants fail to grow well and the soil has been adequately fortified with nitrogen, viruses can be the problem. In addition to slow, stunted growth, Maize Chlorotic Dwarf Virus causes new leaves to emerge tannish-yellow, often with red streaks or margins. When they are infected with Maize Dwarf Mosaic Virus, plants stay low and bushy instead of growing tall, and new leaves show pale streaks and mottled patches of yellow and dark green. Maize White Line Mosaic causes plants to become stunted, and leaves have numerous white streaks.

Damage:

Like other viruses, corn viruses interfere with genetic signalling within the plant. Leaves that are distorted by the virus cannot function normally, so plants stop gaining size and die during stressful weather.

Preventing Problems:

Maize White Line Mosaic Virus persists from year to years in damp soil, so always plant sweetcorn in well-drained soil, and avoid low, wet locations. Many sweetcorn varieties are resistant to common viruses; resistant varieties may show slight symptoms, and then outgrow the problem. Measures that reduce aphid and leafhopper populations will cut the risk of this and other viral diseases in the garden. Grow plenty of nectar-producing flowers to attract aphid predators including ladybirds, lacewings and hoverflies.

Managing Outbreaks:

Infected plants will not make a good crop. Pull them up, cut them into pieces, and compost them in an active compost pile.

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