Races of Colletotrichum lindemuthianum (Sacc. Magnus) Briosi Cavara in major bean growing regions in Tanzania

Abstract

Breeding for resistant varieties has been shown to be the most suitable method to control bean anthracnose caused by Colletotrichum lindemuthianum though the method is challenged by the existence of many races of the pathogen. This work focused on characterizing races of C. lindemuthianum from potential bean agro ecological zones of Tanzania using a set of differential bean cultivars. From 144 anthracnose infected bean samples collected, 50 pure isolates were obtained and characterized whereby 42 races were identified. The most virulent race identified was race 3610 from the Southern Highland zone of Tanzania while the least virulent was characterized as race 0. Race 2 was the most widely spread (4.2 %) found in Northern, Southern highland and in Eastern zones of Tanzania. The work confirms that G2333 can still be used as a potential donor of resistant genes to varieties that are to be grown in Northern, Eastern and Lake zones but not for the varieties from Southern Highland and Western zones of Tanzania since isolates from these zones overcame resistant genes Co-42, Co-5, Co-7 in G2333. 95% of all races which were identified are new and were not specific to either Mesoamerican or Andean origin common bean.   Key words: Colletotrichum lindemuthianum, races, resistant genes, differential cultivars, Anthracnose.