Breeding for resistance to coffee berry disease caused by Colletrotrichum coffeanumNoack (Sensu Hindorf) in Coffea arabica L. I. Methods of preselection for resistance

Abstract

INDEX WORDSCoffee arabica, arabica coffee, coffee berry disease, Colletotrichum coffeanum, resistance breeding. SUMMARYTwo methods of preselection for resistance to coffee berry disease, by artificial inoculation of young coffee seedlings, have been developed recently at the Coffee Research Station in Kenya. The efficiency of these methods has been investigated in a series of experiments by comparing the results of the preselection tests with mature plant resistance, as indicated by visual field scores and artificial inoculation of berries and bud leaves of mature trees and including a large number of varieties and cultivars of Coffea arabica. The preselection test, by which the hypocotyl stems of 6-week old seedlings are inoculated with a spore suspension of the pathogen, proved to be more reliable than the second preselection test with shoot-tips of 10-month old plants. Correlation coefficients between the preselection test and mature plant resistance were resp. r --0.734).80 for the first test against r 0.60 for the latter.

Responses of Compact Coffee Clones Against Coffee Berry and Coffee Leaf Rust Diseases in Tanzania

“…Although van der Vossen et al (1976) found possible correlation between hypocotyls test and reaction of CBD on expanding berries was not the case in this study. Genotypes CVT10 (Ctr127 x (N39 x Rume Sudan selfed F 2 ) and CVT14 (Ctr086 x (N39 x Rume Sudan Selfed F 2 ) showed CBD resistance when green expanding berries were artificially inoculated, but the hypocotyls did succumb to the disease.…”

“…The experiment was arranged in the laboratory in a completely randomized design (CRD) with three replications. Hypocotyls at 5-6 weeks or 5-6 cm were sprayed and inoculated with suspension of C. kahawae strains at 2.0 x 10 6 conidia/ml twice at 48 hr intervals using the method by van der Vossen et al (1976). Three weeks after the date of first inoculation, coffee seedlings were individually scored for CBD symptoms which developed on the hypocotyls using a scale with a range of 0-4 which was developed by van der Graff (1982), where 0 is nil and 4 intense CBD infections.…”

Coffee resistance to the main diseases: leaf rust and coffee berry disease

“…Many different coffee genotypes were tested with local C. kahawae isolates and differential pathogenicity was never observed in this country (van der Vossen et al, 1976). Moreover, differential interactions between host and pathogen population were seldom found in Ethiopia (van der Graaff, 1981).…”

“…Many authors agree that the aggressiveness of the pathogen population shows variability between isolates from the same or different geographic origins (Firman and Waller, 1977;Omondi et al, 1997;Masaba and van der Vossen, 1978;van der Vossen, 1985;Manga et al, 1998;Manga, 1999;Varzea et al, 2002b, Varzea et al, 2001.…”

Races of Hemileia vastatrix and Variation in Pathogenicity of Colletotrichum kahawae Isolates to Compact Coffee Genotypes in Tanzania

“…The experiment was arranged in the laboratory in a completely randomized design (CRD) with three replications. Hypocotyls at 5 to 6 weeks old or 5 to 6 cm tall were sprayed and inoculated with suspension of C. kahawae strains at a concentration of 2.0 x 10 6 spores/ml twice at 48 hr intervals using a method described by van der Vossen et al (1976). The inoculum was prepared from 17-23 old days colonies of the four C. kahawae strains grown in 3.4% malt extract agar containing 0.04% streptomycin.…”