Description:
Sclerotinia sclerotiorum has a wide range of hostsand is non-specific necrotrophic pathogen(over 400 plant species). Another disease names: Cottony soft rot, stem rot, cottony rot. The infection occurs in all growth stages of the plant and mainly in matured plants. Also, the fungus causes post-harvest infections. The pathogen survives in infected plants, dead plant debris as mycelium. It also survives in the soil as hard, round, black structures called sclerotia. Numerous reports indicate that Sclerotinia may have host weeds contributing to the long presence of pathogen’s sclerotia within the field. Sclerotia germinate into mycelium or apothecia. Apothecia are fleshy-coloured,mushroom-like organs that after rain or irrigation can produce ascospores, that eventually infect the upper parts of the plant and especially “week” plant tissue with white mycelium that then spreads in the other healthy parts of the plant. The pathogen spread through wind, irrigation or rainwater, contaminated tools, worker’s clothes and some time with contaminated seed coat. The disease symptoms usually start at plants parts close to the soil. Last but not least, the optimum conditions are: a) high environmental and soil humidity, and b)temperature 15-22oC
Symptoms:
Leaves: Discoloration, necrotic areas and wilting
Stem: Usually starts in the plant crown—watery-soaked lesions covered with white, cottony mycelium. We can quickly diagnose the disease in late stages where pea-form structures (sclerotia) are developed into the mycelium in the infected areas’ outer surface. Sometimes, sclerotia may be observed into the stem/petioles. This leads to the wilting and total necrosis of the plant.
Fruits: Light dark lesions following with white fungal growth. The fruit decays
Hosts: tomato, sunflower, bean, tobacco, pepper, onion, melon, eggplant, squash, lettuce, carrot etc
Taxonomy:
| Kingdom | Fungi |
|---|---|
| Class | Discomycetes |
| Order | Helotiales |
| Family | Sclerotiniaceae |
| Genus | Sclerotinia |
| Species | S.sclerotiorum |
References:
Vegetable diseases”- Panagopoulos G.C
Purdy LH. Symposium on Sclerotinia Sclerotinia sclerotiorum: History, Diseases and Symptomatology, Host Range, Geographic Distribution, and Impact.