Effect of Rust on Yield of Susceptible and Resistant Asparagus Cultivars. Dennis A. Johnson, Plant Pathologist, Washington State University, Irrigated Agriculture Research and Extension Center, Prosser 99350. J. D. Lunden, Research Technician III, Washington State University, Irrigated Agriculture Research and Extension Center, Prosser 99350. Plant Dis. 76:84-86. Accepted for publication 12 August 1991. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/PD-76-0084.

The effect of rust, caused by Puccinia asparagi, on yield of two slow-rusting and two rust-susceptible cultivars of asparagus (Asparagus officinalis) was determined in two consecutive years in the field. Rust was or was not controlled with a fungicide. Rust reduced total weight and number of spears produced by the susceptible cultivars but not by the resistant cultivars. Weight per spear was reduced only after the second consecutive year of rust infection in the susceptible cultivar Mary Washington. The second year of infection reduced relative yields more than the first year for the susceptible cultivars.