The alfalfa mosaic virus ( Alfalfa mosaic virus , AMV) induces two main symptoms on leaves :
- an mosaic aucuba-type , generally quite vivid;
- necrotic lesions in spots , often beginning at the base of the leaflets or distributed over the entire blade, sometimes leading to necrosis of the veins (figure 1).

Of necrotic lesions , longitudinal and unilateral, may then appear on the rods of a length up to 20 cm (Figure 2). The apical buds are sometimes completely destroyed by necrosis, as well as the neighboring young leaves.

In the presence of a particularly aggressive strain, the necrotic lesions can be lethal to the plant whole infected early on. In this case, reddening and browning of the phloem vessels can be observed along their entire length.

The fruit can also express various symptoms. Young fruits may drop, be misshapen, or have their growth blocked. Older ones sometimes present necrotic spots , external or internal, more or less extensive and hollow (Figures 3 and 4). These lesions can coalesce and lead to generalized necrosis. They can grow almost normally, but be slightly bumpy and reveal an epidermis speckled with rounded, brown-colored macules.