Journal of Plant Studies; Vol. 2, No. 2; 2013
Eighteen clones of coffee rust differentials were used to characterize rust races prevailing in the coffee growing
areas in Arusha, Kilimanjaro, Mara, Bukoba, Kigoma, Mbeya and Ruvuma regions. The results showed the
presence of seven new Hemileia vastatrix races causative agent for coffee leaf rust (CLR) in the surveyed coffee
growing areas. The races were: XLI (v2, 5, 8), XLII (v2, 5, 7, 8 or v2, 5, 7, 8, 9), XV (v4, 5), XXX (v5, 8),
XXXIII (v5, 7 or v5, 7, 9), XXXIV (v2, 5, 7 or v2, 5, 7, 9), XXXIX (v2, 4, 5, 6, 7, 8, 9). Four strains of
Colletotrichum kahawae originating from 4 coffee ecosystems were used to test their level of pathogenicity on
16 compact coffee genotypes, Ctr088 and commercial variety N39. The four C. kahawae strains were less
pathogenic to six compact coffee genotypes; CVT2, CVT4, CVT5, CVT7, CVT8 and CVT13, completely nil
pathogenic to Ctr088, but significantly highly (P < 0.05) pathogenic to N39. Coffee genotype Ctr088 was
confirmed to be a potential donor of developing coffee berry disease (CBD) varieties with durable resistance.
Differential interaction between the compact genotypes and the four C. kahawae strains needs further
investigation.