Main symptoms

Significant differences in symptoms are observed depending on the species or variety infected, as well as on the strain considered of watermelon ( mosaic virus Watermelon mosaic virus , WMV), which sometimes makes visual diagnosis difficult.

In zucchini, the first sign of WMV infection is leaf twitching towards the interior of the leaf blade (Figure 1). 

The strains CL generally cause a slight mottling on leaves (Figure 2) and no symptoms on fruit, making them virtually no impact on performance.

On the other hand, EM strains most often cause marked leaf symptoms: mosaic (Figures 3 and 8) sometimes very deforming, with filiformism (Figures 4, 5 and 9), and blisters (Figure 6). These symptoms can also be confused with those produced by Zucchini yellow mosaic virus (ZYMV).

Symptoms on fruits are also often marked (Figure 7). Light green spots that are slightly depressed may appear, as well as slight deformations, which may make them unmarketable. Dark green rings or arabesques and green mosaics are observed on varieties with yellow fruits.