Previous View
APSnet Home
Plant Disease Home



Field Evaluation of Seed, Pod, and Stem Rot in White Lupine Germ Plasm. M. A. Faluyi, Department of Botany, Ondo State University, Ado-Ekiti, Ondo State, Nigeria. D. E. Mather, G. N. Atlin, L. C. Merrick, and T. C. Paulitz. Department of Plant Science, McGill University, Macdonald Campus, 21,111 Lakeshore, Ste-Anne-de-Bellevue, Québec, Canada H9X 3V9; Department of Plant Science, Nova Scotia Agricultural College, P.O. Box 550, Truro, Nova Scotia, Canada B2N 5E3; University of Maine Sustainable Agriculture Program, 5722 Deering Hall, Orono 04469; and Department of Plant Science, McGill University, Macdonald Campus, Ste-Anne-de-Bellevue, Québec, Canada H9X 3V9. Plant Dis. 77:926-929. Accepted for publication 17 May 1993. Copyright 1993 The American Phytopathological Society. DOI: 10.1094/PD-77-0926.

Disease symptoms were evaluated on 92 accessions of white lupine (Lupinus albus) grown in replicated field trials in Québec, New Brunswick, and Nova Scotia. Pod, stem, and seed rot symptoms caused by Phoma sp. were more severe at the Maritime sites than at the Québec site. At all sites, there were significant differences among accessions. Pod lesions were more severe on early-maturing than on late-maturing accessions. Pod lesion ratings taken in the field were not correlated with severity of discoloration on harvested seed. Accession means for ratings of seed discoloration from each site were positively correlated with those from the other sites, with more similarity between the two Maritime sites than between the Québec and Maritime sites. The incidence of infection with Phoma sp. and Pleiochaeta setosa was evaluated on random samples of seed for a subset of nine accessions. Phoma sp. was common in both regions, whereas P. setosa was common in the Maritime region but rare in Québec. Among these nine accessions pooled over all sites, there was no significant correlation between the incidence of infection by the two pathogens and severity of seed discoloration, even though inoculation with Phoma sp. at the Québec site appeared to induce more seed discoloration. At the Québec site, however, 80% of the samples that had low levels of seed discoloration also had low levels of Phoma infection. Thus, it may be possible to use seed discoloration to screen white lupine germ plasm for resistance to Phoma sp. and other seedborne pathogens, at least in environments where conditions do not favor colonization of pods and seeds by other saprophytes that may discolor seeds. Severity of pod symptoms may reflect the physiological age of the plant at the time of assessment rather than genetic resistance and may not be as useful as seed discoloration in evalution of resistance in the field.