Common crupina from the United States varies in susceptibility to Puccinia crupinae

Accessions of common crupina (Crupina vulgaris Cass.) from four locations in the United States (US) were tested for susceptibility to a Greek isolate of Puccinia crupinae in evaluations for biological control. Morphological and developmental variation is known between populations of U.S. common crupina. Two accessions ('A', Modoc Co., Calif.; and 'C', Lake Chelan, Wash.), have a flat rosettes, and two others ('B', Salmon River, Idaho; and 'D', Sonoma Co., Calif.) have upright rosettes. Similarity of 'A' and 'C' and of 'B' and 'D' has been noted also for chlorophyll content, seed size, and flowering. Plants of each accession were inoculated with 104 urediniospores/ml, given dew at 18 degree C for 48 hr (dark, with one 8 hr light period), and placed in a 20 degree C greenhouse for symptom development. Accession 'A' developed a few small pustules with necrotic rings; 'B' developed a few small pustules and infected leaves became necrotic and died; 'C' developed many large pustules with heavy sporulation and infected leaves senesced pre-maturely; and symptoms on 'D' were similar to those of 'B'. Individual leaves either were killed or they produced normal pustules, although less disease developed on 'A' than on 'C'. Reaction types correlated with other characteristics distinguishing these accessions.