How to Manage Pests

UC Pest Management Guidelines

SYMPTOMS

Symptoms of maize dwarf mosaic include narrow, light green to yellow streaks along the veins of leaves, leaf sheaths, and husks. As infected plants continue to grow and the temperature rises, the mosaic symptoms may disappear while the young leaves become more yellow. Plants may be stunted and have numerous tillers and poor seed set. Infected plants may be predisposed to ear rot and stalk rot.

COMMENTS ON THE DISEASE

Maize dwarf mosaic virus includes several strains that were once grouped in the sugarcane mosaic virus complex. One of the principal strains in corn in California is maize dwarf mosaic virus, strain A. The virus is transmitted by many species of aphids, including the corn leaf aphid (Rhopalosiphum maidis), the greenbug (Schizaphis graminum), and the green peach aphid (Myzus persicae). Although many grasses are infected by this strain of the virus, the principal overwintering reservoir host is johnsongrass. Most outbreaks of maize dwarf mosaic in corn can be traced to nearby johnsongrass.

MANAGEMENT

Use resistant hybrids to prevent the development of this disease. Eliminating johnsongrass within a quarter of a mile around the corn field may effectively reduce disease incidence. Delay planting until aphid flights are over.

PUBLICATION

UC IPM Pest Management Guidelines: Corn
UC ANR Publication 3443
Diseases
R. M. Davis, Plant Pathology, UC Davis

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