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Main symptoms

 

Small fatty lesions (2 to 4 mm) are observed on the underside of the leaves at first. These develop in small circular to angular spots when delimited by the veins. Initially chlorotic, they turn slightly brown while necrotizing and take on a beige tint (Figures 1 and 2). Sometimes reaching up to 7 mm, a yellow halo surrounds them.

Note that these spots are observed on the periphery as well as on the inside of the limbus, and that they can merge and give rise to more extensive brown necrotic lesions. In addition, these lesions can go unnoticed for some time, due to their limited dimensions.

Necrotic lesions are sometimes seen on young stems and petioles .

Young fruits are particularly sensitive. Fruits show various symptoms depending on their stage of development and climatic conditions (Figures 3 to 8). We can observe small superficial and slightly depressed watery lesions, or light green with a darker center, but also beige circular alterations surrounded by a dark brown border, brown necrotic spots surrounded by a chlorotic halo

Amber-colored exudates sometimes form at the lesions and they can develop in depth and reach internal tissues which darken; the seeds thus become contaminated (figure 9). Some early and severely affected fruits show cracks, canker lesions (figure 10); they are sometimes strongly deformed. They can decompose under the complementary action of secondary invaders.

Last change : 04/16/21
xanthomonas_courge_DB_153
Figure 1
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Figure 2
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Figure 3
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Figure 4
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Figure 5
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Figure 6
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Figure 7
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Figure 8
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Figure 9
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Figure 10