Black sclerotia

Fig. 4.4. Black sclerotia and soybean seed covered with mycelium of Sclerotinia sclerotio-rum. (Photo courtesy of D. Mueller)...

Similar symptoms on tubers as silver scurf. Small black sclerotia present on the lesions. A problem in potatoes for pre-packing. 

If black sclerotia (black scurf) present on seed tuber can lead to poor emergence. On young plants may cause sunken brown stem lesions below ground. Stem infection can lead to yellowing and rolling of leaves. In severe cases shoots may die. White mycelium may be found at base of stems. 

Resting structure a tme sclerotium (ergot) with a light-colored interior and a black rind, a phialidic anamorph sometimes present at... 

C. tripsaci was described from Tripsacum dactyloides (L.) L. from the southeastern United States. Sclerotia are initially white, becoming brown or black at the distal end, nearly conical, 4-5 mm in diameter at the base. Stipes are whitish purple, bearing gray to grayish white capitula. Perithecia are elliptical, 390 X 153-187 pm. Asci are 145-175 X 2-3 pm, with ascospores of 130 pm. Conidia are hyaline, fusoid to lunulate, 17.4-37.7 X 2.0-8.7 pm (Fig. 1 v). Except for the size of the sclerotium, C. tripsaci is morphologically similar to C. gigantea. 

In sorghum ergot, Claviceps africana, the sclerotia were thought to be rounded, 3-5 mm in diameter, with reddish brown spots, until another population of this fungus specialized on Hyparrhenia spp. was discovered (D. Frederickson and S. Pazoutova, unpublished), whose sclerotia are cylindrical and brown to black, 2-4 mm in length, and 0.5-1 mm wide. Here, the sclerotium is shaped only by floral cavity, and even the color is influenced by the pigments supplied by the host. Sclerotia formed on sorghum cultivars with dark seeds are more... 

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