Cucumber, Pumpkin, Squash Diseases - Watermelon Mosaic Virus (WMV)
WMV causes leaf distortion
Fruit infected with WMV frequently exhibit color breaking.
Fruit infected with WMV frequently exhibit warts.
WMV is in the genus Potyvirus. It is spread in a nonpersistent manner by aphids. It affects summer and winter squash, zucchini, gourds, and pumpkins.
The virus causes mosaic patterns and leaf distortion. The fruit frequently show color breaking and warts.
The virus is not seedborne; it is only spread by aphids, which acquire the virus from infected weeds or alfalfa. Symptoms usually begin to show in June. Often the first symptoms are seen on field edges and aphids continue to move the virus across the cucurbit field. The virus overwinters in infected perennial weeds or alfalfa.
Management options are very limited, and include weed control, crop rotation, and keeping cucurbit fields away from alfalfa fields. There are resistant summer squash and zucchini varieties (some are GMO) but there are no resistant winter squash or pumpkin varieties. Insecticides for aphids are of limited value to control the disease.