Corn (Zea mays) Rusts (Puccinia sorghi, P. polysora, Physopella zeae) II. A comparative study and natural enemies

Abstract

The author studied four different types of rusts. Two of them were collected in corn, in parasitical condition, another in Guatemala grass (Tripsacum laxum) and the fourth one in sorghum (Sorghum vulgare). The macro and microscopical characteristics identified them as P. sorghi and P. polysora on corn, P. polysora on T. laxum and P. purpurea on S. vulgare. Differential biological behaviour was observed, as well as the presence or absence of stages in the complete cycles and incubation time after artificial inoculation. The author observed also the ocurrence of a natural enemy, Darluca filum, which was regarded as the limitating factor in the spreading of the corn leaf rusts in the south-center region of Brazil.