Symptoms of diseases caused by the potyviruses ZYMV, PRSV-W and WMV-2 can look very similar and hence it is difficult to separate these diseases by symptoms in the field.
Characteristic symptoms may be seen with inward curling of leaves and serrated leaf margins. This may be on few plants and tends to be scattered around the field.
Unique symptom caused by ZyMV, PRSV-W, WMV-2 may include blisters on the leaf surfaces which are darker than the rest of the leaf lamina and thus an identifiable characteristic symptom..
The leaf may show general wrinkling over the entire lamina, and the majority fo the leaf may loose chlorophyll. The rest of the area have blister like appliance which remains green.
Unique discoloration pattern of cucurbit leaves with yellowish sections in between green regions. Initial serrated appearance of leaf margins can also be noticed.
Stunted inward curling leaves with a “wired” or strapped appearance. The disease is mostly commonly an issue in pumpkin and squash, but less of watermelon and other cucurbits.
The disease can cause symptoms of the fruits of many cucurbits. In case of pumpkin bulging of fruits can be caused by infection by ZYMV, PRSV-W and WMV-2.
Affected fruits of squash shows marbling, and green markings on yellow fruit. Some fruits may also show circular marks on the fruits. These fruits are non-marketable.
The diseases caused by ZYMV, PRSV-W, and WMV-2 are not a major issue on watermelon. However, in rare cases marbling of fruits can as seen on watermelon.
A pumpkin fruit with distorted shape with bumps and indentations. The viruses causing these symptoms can also be found in mixed infection with other viruses like CuLCrV and CYSDV.
Potyviruses can be identified by virus inclusions bodies in plant cell using staining procedures a seen in this picture. This is not a definitive diagnostic tool for any of the potyviruses.