Main symptoms

The first symptoms of the aphid-transmitted cucurbit ( yellows virus Cucurbit aphid-borne yellows virus , CABYV interveinal ) are usually manifested by the development of yellow plaques on older leaves, 3 to 4 weeks after inoculation with the aphids ( figure 1). Then, gradually, this yellowing spreads and affects several leaf stages at the base of the plants (figures 2 and 4), some leaves being able to turn completely yellow, with the exception of a few islands of tissue whose green color persists. Significant differences in symptom intensity are observed depending on the season (symptoms are clear in summer and more discreet in winter) (Figures 3 and 5), but also depending on the stage of infection and varietal susceptibility.

In France, on Charentais type melons, there is a more or less pronounced yellowing of the old leaves , which thicken and become brittle. No symptoms are observed on the young leaves. In other varieties, yellowing of the plant can be widespread and greatly affect yield.

There is a reduction in the number of fruits per plant, due to the sagging of the flowers. However, the fruits produced on plants infected with CABYV remain marketable.

In cucumber: Symptoms of yellowing and thickening of the blade are observed on older leaves. The number of leaves affected varies depending on the variety and the precocity of the infection. There is a reduction in the number of fruits per plant, due to sagging flowers, but the appearance of the fruits is not altered.

In zucchini: Symptoms of yellowing and thickening of the leaf blade are observed on older leaves. The number of leaves affected varies depending on the variety and the precocity of the infection. Fruit production does not appear to be affected by CABYV in zucchini.

In watermelon: Watermelon generally exhibits fairly inconspicuous symptoms with partial yellowing of the older leaves.