Watermelon Mosaic Virus

HOSTS

• Cucurbits

OVERVIEW

Watermelon Mosaic Virus (WMV) is in the genus Potyvirus. It is spread by feeding aphids and can affect summer and winter squash, zucchini, gourds, and pumpkins. This disease is widespread in Utah watermelon and squash production and occasional in cantaloupe.

BIOLOGY

WMV is not seedborne, but spread by aphids which acquire the disease by feeding on  infected weeds or alfalfa. It is a concern from June (or earlier if winter was mild or crops are grown in high tunnels) until the end of the season. Symptoms are often first seen at field edges and progress through the field as aphids move the virus. The pathogen overwinters in perennial weeds or alfalfa.

SYMPTOMS

• Stunted growth.
• Leaf malformation.
• Yellowing or light green mottling on foliage.
• Marginal chlorosis on foliage.
• Dwarfed, mottled, or spotted fruit.
• Fruit with warts, or raised blister-like areas.

SCOUTING

• Watch for symptoms starting in June until the end of the season.
• First symptoms are often seen on field edges.
• Monitor for aphid activity starting in June.

GENERAL MANAGEMENT

• Control weeds as they can act as alternative hosts for aphids.
• Rotate crops.
• Avoid planting cucurbits near alfalfa fields.
• Use resistant varieties when available. 

INSECTICIDES

Insecticides for aphids are of limited value to control this disease