VIEW ARTICLE

Resistance

Development of Rust on Asparagus Cultivars After Inoculation with Basidiospores, Aeciospores, and Urediniospores of Puccinia asparagi. Dennis A. Johnson, Associate and extension plant pathologist, Washington State University, PO Box 30, Prosser 99350; Phytopathology 80:321-325. Accepted for publication 5 October 1989. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/Phyto-80-321.

Asparagus cultivars were inoculated with urediniospores and aeciospores in the greenhouse and with basidiospores in the greenhouse and in the field. Latent period and numbers of pustules were determined. Number of aecia per shoot varied significantly (P = 0.05) among cultivars after infection by basidiospores. Latent period and number of uredinia per linear centimeter of shoot varied significantly (P = 0.05) among cultivars after infection by either aeciospores or urediniospores. Length of latent period and number of uredinia after either urediniospore or aeciospore infection in the greenhouse were correlated with the area under the disease progress curve (AUDPC) measured in the field. However, latent period and number of uredinia of some individual cultivars with low values of AUDPC did not differ significantly (P = 0.05) from those of cultivars with high AUDPC values. Therefore, monocyclic test measurements of components of rust resistance in the greenhouse should not be used to supplant field epidemics when selecting for resistance in asparagus. Number of aecia was not correlated with severity of rust in the field or with latent period or number of uredinia after either aeciospore or urediniospore infection. Latent period after aeciospore infection in the greenhouse was positively correlated with latent period (P = 0.01) after urediniospore infection and negatively correlated with number of uredinia (P = 0.05) after urediniospore infection. Thus, cultivars reacted similarly when infected with either aeciospores or urediniospores, and they reacted differently in three of 12 cultivars when infected with either urediniospores or basidiospores. Mature asparagus shoots were resistant to infection by basidiospores.