Symptoms on leaves of bacterial scab caused by Xanthomonas spp. are quite comparable to those described for Pseudomonas syringae pv. tomato : small, fatty, translucent lesions appearing at random on the leaflets or at the edge of the leaf blade and subsequently resulting in brown to black spots (Figures 1 to 3). They are circular or slightly angular, with a diameter of 2-3 mm, and sometimes haloed with a yellow halo. Their center dries up, and degraded fabrics can eventually fall off. In the presence of moisture, these spots can spread and merge, altering large areas of the blade that eventually necrosis and dry out (Figure 4). In some cases, whole leaves turn yellow, dry out; they can either remain attached to the plant or fall. Young leaves are often more sensitive.

Of similar lesions are seen on other organs, especially on petioles , the stem (Figure 5), the stems and sepals fruit. They are frequently more extensive and elongated than on the leaflets. When present on the flower pedicels, a few flowers may fall.

Greasy lesions , dark green to black in color, first form on green fruits . They subsequently give rise to raised corky pustules , cracked up to 1 cm in diameter (Figure 6). A fatty halo sometimes surrounds them (figure 7). The fruits achieved for canning, are harder to peel.

These lesions on fruits can be confused with the damage caused by impacts from hailstones. Let us add that it is not uncommon for this bacterium and Pseudomonas syringae pv. tomato are found at the same time in the same crops in temperate regions.