Aggressiveness and Virulence of Three Species of Colletotrichum spp. in Cassava Cultivars Produced in the Northern Region of Brazil

Abstract

Cassava (Manihot esculenta Crantz) can be affected by several diseases, among which anthracnose stands out. Despite its importance, few studies have been conducted on aggressiveness and virulence in cassava-producing areas of northern Brazil. Isolates of three species of Colletotrichum (C. musicola, C. chrysophillum, and C. truncatum) were obtained from collections of diseased cassava plants previously collected in the states of Tocantins and Pará. Inoculation was performed on the leaves of nine cassava cultivars grown in pots. The inoculated plants were kept in a humid chamber for 48 hours at a temperature of 25°C and after two days, the first symptoms appeared on the leaves. All inoculated Colletotrichum species caused symptoms of anthracnose on the leaves. Although C. musicola was, in general, the most aggressive species, there was a significant difference in virulence between C. chrysophillum and C. truncatum. Among the studied cultivars, “Água morna” proved to be more resistant, showing the lowest values for both aggressiveness and virulence measures. The “Lagoão” cultivar was the most susceptible in both variables. Currently, there are no recommendations for the effective control of anthracnose in cassava; however, the results obtained in the present work confirmed the variation in aggressiveness and virulence of Colletotrichum species that infect cassava, as well as the existence of possible sources of resistance. These results provide important information in the management of anthracnose and in the implementation of a genetic improvement program aimed at the development of cultivars resistant to anthracnose in commercial tropical areas.