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Main symptoms

Colletotrichum coccodes seems capable of attacking almost all the organs of the tomato: roots, leaves, stem and fruits. It is on fruits and roots that its symptoms are frequently observed.

On fruits , symptoms anthracnose appear at maturity as tiny light brown lesions , which progressively develop into small circular, damp, dull spots. As they extend, they become concave and their center gradually turns brown (Figures 1 to 3). The underlying flesh is rather discolored and grainy in texture. Concentric rings are sometimes visible, as well as dark brown to black structures: the microsclerotia of C. coccodes . We can also observe acervuli in which stand black bristles ( setae ) . These acervuli produce, in wet periods, masses of clearly visible salmon-colored mucous spores on the surface of the lesions which remain smooth and intact. Often, many spots develop at the same time on the same fruit. On confluence, they end up covering large portions and give rise to rotting .

On the roots , this fungus is responsible in particular for brown lesions . The rootlets are few or non-existent because a brown cortical rot has destroyed them. The cortex of the main roots shows dark brown lesions, more or less suberized (Figures 4 to 6). Stem base rot has occasionally been reported. The decomposed cortex is detached in places from the central cylinder. In soilless culture, the attacked roots are poorly developed, discolored and partially decomposed (Figure 7). Of root rot and leaf wilts are also attributed to this fungus.

In addition to the associations mentioned above, C. coccodes is found with Thanatephorus cucumeris (ex R. solani ) in the United States on crown cankers occurring in industrial tomato crops. On the stem, it seems to behave mainly as a secondary invader because its development is rather limited there. On the roots, the association of these two fungi would lead to more severe attacks .

On potatoes, its inoculation with Verticillium dahliae would lead to much more marked wilting than those observed when the plants are inoculated with only one of these pathogens. It is also part of the complex of microorganisms causing brown root rot (brown root rot complex), also integrating Fusarium oxysporum f. sp. radicis-lycopersici, F. solani, P. lycopersici, Pythium debaryanum and T. cucumeris.

It should be noted that in certain heavily contaminated soils, C. coccodes would be capable of destroying seeds during germination and tomato seedlings. This situation is certainly very rare now. In addition, it would be able to produce small brown spots on leaves , circular and surrounded by a yellow halo.

Last change : 04/13/21
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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