East African Work on Breeding Maize Resistant to the Tropical American Rust, Puccinia Polysora

Abstract

Since 1952 Puccinia polysora under has become widespread in maize in the tropical areas of East Africa, and severe attacks have been shown to reduce yield greatly. Two physiologic races have been recognized, 'EA.I' being today the prevalent race in the field and 'EA.2' being known as yet only in the Muguga glasshouses. Experimental infection trials in glasshouses at Muguga, Kenya, failed to demonstrate resistance in any African maize variety; but among maize’s imported from Central America and the Caribbean plants were found that showed the hypersensitive type of resistance. From these, lines were bred that were pure for either of two genes: Rppl. conferred high resistance to Race EA.I but none to EA.2; while Rpp2 conferred a lesser, but effective, resistance equally to both rust races. Field breeding at three stations in East Africa was successful in incorporating each of these genes separately in locally adapted maize varieties; and considerable bulks of pure-breeding resistant maize’s were expected to become available during 1957 and later years.