Main symptoms

Significant differences in symptoms are observed depending on the species or variety infected, but also on the strain considered, which sometimes makes visual diagnosis difficult.

In melons, the squash mosaic virus ( SqMV ) induces a mosaic leaf more or less strong often accompanied by interveinal discoloration, which gives the blade a characteristic appearance called by the Anglo-Saxons " vein-banding "(Figures 1 to 3). Ring spots can also be observed. Sometimes the symptoms are much more accentuated and we can witness strong deformations of the leaves (figure 4) which then take on an "oak leaf" appearance (figure 5).

The growth of the twigs does not seem to be affected and the symptoms may diminish or even disappear on the young shoots (recovery phenomenon).

In Charentais-type varieties, the symptoms of green mosaic (figure 6) on the fruits are very spectacular. These fruits cannot be marketed.

In zucchini : Symptoms of often very deforming mosaic (filiformism) are observed. Fruits may show blisters similar to those caused by ZYMV.
In cucumber : Certain strains infect cucumber by causing mosaicism and chlorotic or ring spots on the foliage.
In watermelon : Most strains of SqMV do not infect watermelon. However, one strain has been reported in Arizona to cause severe mosaicism in this species.