An Outbreak of Anthracnose Caused by Colletotrichum gloesporioides f.sp. manihotis in Cassava in North Western Tanzania

摘要

Severe outbreak of anthracnose diseases caused by Colletotrichum gloesporioides f.sp. manihotis on cassava (Manihot esculenta Crantz) occured in north-western Tanzania in October, 2011. Thirteen cassava leaf samples with disease symptoms were collected from Maruku Agricultural Research Institute (MARI) and from farmers. The collected samples were tested for infection using Blotter method. The results indicated that, all 13 leaf samples (100%) were infected by C. gloesporioides f.sp. manihotis. Three isolates of the fungus per sample were subcultured on Potato Dextrose Agar (PDA) for seven days then each isolate was sprayed-inoculated onto 4-week-old sprouting leaves of cassava cuttings, var Mkombozi grown in pots in the screenhouse maintained at 27?C and relative humidity of 85% - 90%. All isolates were pathogenic on cassava and produced similar symptoms as those observed under field conditions. This is the first report of C. gloesporioides f.sp. manihotis a causal agent of anthracnose disease of cassava in Tanzania.