BLACK SPOT DISEASE OF LENTINULA-EDODES CAUSED BY THE HYPHOZYMA SYNANAMORPH OF ELEUTHEROMYCES-SUBULATUS

The Hyphozyma synanamorph of Eleutheromyces subulatus was found to be the cause of black spot disease of Lentinula edodes fruiting bodies. M ultiplication of yeastlike cells and hyphae of Hyphozyma resulted in b lackening and mild lysis of the infected host cap tissues where partia lly degraded skeletal microfibrils of host cell walls were abundant. I n general, host tissue lysis remained superficial; however in some cas es, Hyphozyma caused severe lysis and formed deep cavities containing remnants of highly dissolved host cell walls and numerous yeastlike ce lls of the pathogen. Enzyme assays demonstrated the ability of Hyphozy ma to produce both chitinase and beta-(1,3) glucanase enzymes, require ments for hyphal wall degradation. On agar, conidiogenesis is enterobl astic in the Hyphozyma morph, whereas it is apparently holoblastic in the Eleutheromyces morph. No evidence of phialidic conidiogenesis was obtained.