Browsing by Author "Kilambo, D. L."

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Races of Hemileia vastatrix and variation in pathogenicity of Colletotrichum kahawae isolates to compact coffee genotypes in Tanzania
(Journal of Plant Studies, 2013-05-30) Kilambo, D. L.; Reuben, Shazia O. W. M.; Mamiro, D.
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.
Responses of compact coffee clones against coffee berry and coffee leaf rust diseases in Tanzania
(Canadian Center of Science and Education, 2013-05-28) Kilambo, D. L.; Rebeun, Shazia O. W. M.; Mamiro, D. P.
The utilization of resistant Arabica coffee (Coffea arabica) varieties is considered as the most economical control for coffee berry disease (CBD) and coffee leaf rust (CLR) in Tanzania. The resistance levels of varieties at field and laboratory conditions were assessed through their phenotypic disease reaction response to CBD and CLR. In this study sixteen (16) compact hybrids of C. arabica plus four (4) standard cultivars were evaluated under a range of environmental conditions in on-station and on-farm trials in Tanzania. Also four (4) Colletotrichum kahawae strains of the pathogen responsible for CBD infection; 2010/1, 2010/2, 2006/7 and 2006/14, and Hemileia vastatrix uredospores were used to test the sixteen (16) hybrids through artificial inoculation under controlled conditions (temperatures between 19 to 22 ºC, R.H 100%). Results showed that a significant level of variability (P < 0.05) occurred between the sixteen (16) compacts, three (3) standard checks and N39 a commercial susceptible variety across trials. Compact genotype CVT14 (PNI086 x (N39 x Rume Sudan Selfed F2) showed resistance to the four strains of C. kahawae and Hemileia vastatrix. Differential reactions on compact genotypes were found to C. kahawae and H. vastatrix strains existing in different coffee growing regions in Tanzania; genotypes CVT4 (PNI088 x (SL34 x HdT) x Kent x Rume Sudan) and CVT13 (PRO127 x (Blue Mountain Jamaica x Cioccie) x Rume Sudan) showed partial resistance to C. kahawae strains 2010/1, the genotypes were susceptible to strains 2010/2 but resistant to strains 2006/7 and 2006/14. This shows that host response reaction can be used as criteria for varietal assessment when evaluated at different locations.