Caffeine also not good for growing sclerotia either
Caffeine, IBMX, and NaF all block sclerotial development and are expected to increase cAMP levels. Elevated cAMP levels appear to block early sclerotial development since sclerotial initials are not observed or are greatly reduced in number in cultures amended with cAMP. Developing cultures transferred to cAMP-containing medium before sclerotial initiation did not produce sclerotia, whereas cultures transferred after sclerotial initiation continued to develop mature sclerotia. Although cAMP regulates sclerotial development, the nature of this regulation remains uncertain. cAMP regulation may be indirect in that signaling through a cAMP-dependent pathway may stimulate filamentous growth, resulting in hyphae which fail to differentiate into sclerotia.
http://aem.asm.org/c.../full/64/7/2539