Crops
Classic Symptoms of Rhizoctonia on Salads
- Organs attacked :
| Leaves | Rod | Collar |
- Symptoms :
- Damping off , strangulation of the stem of plants located at ground level, more or less brown and of rather dry consistency, leading to the death of these (figures 1 and 2).
- Brown to blackish lesions located on the lamina momentarily respecting the main vein (figures 3 to 4). They spread rapidly and more or less wet rot sets in (figure 5). Subsequently, it gains the leaves of the heart and sometimes even the stem. The collar can be belted later.
- Numerous reddish to brown alterations appearing both on the petioles, the midrib and on the blade of the lower leaves (figure 6). On the latter, their evolution seems faster and the tissues give the impression of "melting".
- More aerial leaf lesions (figure 7), and rotting of the main leaf veins (figure 8).
- Yellowing and wilting of heavily attacked plants.
- Signs : several fungal structures make it possible to confirm the presence of R. solani on or near the altered tissues:
- often discrete whitish to brown filaments running on the germinated seeds, the collar, and the leaf veins in particular (figure 9);
- more rarely ill-defined, brown masses, visible locally on the damaged tissues (pseudo-sclerotia) (figure 10).
- Confusions possibles : Oomycètes ( Pythium et Phytophthora spp.), Sclerotium rolfsii , Botrytis cinerea , Pectobacterium carotovorum , etc.
- Affected production areas :
| Guadeloupe |
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Figure 9
Figure 10