VIEW ARTICLE

Etiology

Host-Parasite Relations in Uredial Infections of Peanut by Puccinia arachidis. Marion Cook, Former graduate student, University of the West Indies, Jamaica, Present address: c/o EMRO, c/o WHO/OMS, 1211-Geneva-27, Switzerland; Phytopathology 70:822-826. Accepted for publication 8 January 1979. Copyright 1980 The American Phytopathological Society. DOI: 10.1094/Phyto-70-822.

Germination of Puccinia arachidis uredospores and the subsequent penetration and infection processes on leaves of Arachis hypogaea were studied in detail. Resistance to infection appeared to be related to changing wettability of the leaves with age; the rate of change varied among the cultivars investigated and affected spore retention and probably germination and appressorium formation. Analyses of regressions of the densities of the characteristic structures of the different stages of infection on the density of those of the previous stage showed no significant differences among the cultivars until the uredial stage when physiologic resistance was expressed in the failure of a large proportion of chloronemic flecks to become uredia.