Main symptoms

The melon ( virus Melon necrotic spot virus, blight MNSV) causes more or less intense symptoms: systemic necrotic spots on the foliage, necrosis on the petioles and stems and sometimes wilting of twigs or the entire plant.

The symptoms observed on melon vary a lot depending on varietal sensitivity and the season (they are most marked in early spring and fall). The first symptoms are necrotic spots (Figure 1)  one to a few millimeters in diameter which most often appear near the petioles  (Figures 2 and 3)  on one or two leaves . These spots have an "oily" appearance on the underside of the leaves (Figures 4 to 6). Gradually, and depending on varietal sensitivity, these spots appear on other leaves, or even spread to the whole plant.

Necrosis is observed on the petioles and stems (Figure 7)  and necrotic spots can sometimes appear on the fruits.

In cucumber: symptoms are expressed by necrotic spots 5 to 10 millimeters in diameter on the leaves. These spots can then merge and cause necrosis of the leaf or even of an entire branch. In co-infections with CGMMV, oily chlorotic spots may be observed on the fruits.