Location: Foreign Disease-Weed Science
Title: Characterization and evaluation of target and host: Ramularia crupinae, a candidate for biological control of two varieties of Crupina vulgaris in the United States Authors
Submitted to: Mycoscience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 17, 2014
Publication Date: January 25, 2014
Citation: Bruckart, W.L., Eskandari, F., Berner, D.K. 2014. Characterization and evaluation of target and host: Ramularia crupinae, a candidate for biological control of two varieties of Crupina vulgaris in the United States. Mycoscience. 71:40-48. Interpretive Summary: Common crupina is a very important weed in the western United States (U.S.). A disease was discovered in France that may be useful for natural (or biological) control of this plant, but it needed to be tested. The disease is caused by a fungus called Ramularia crupinae. Results of tests this study show that the plant is damaged when it becomes infected. In another part of the study, it is apparent that greatest reduction in the number of seeds the plant makes will occur if leaves on the upper part of the plant are diseased. Inoculation of related plants from the U.S. showed that none of them had symptoms or were damaged. Therefore, our conclusion is that this fungus would be safe to use in the U.S. for biological control of common crupina and that the U.S. would not be in danger, if R. crupinae were introduced for crupina control.
Technical Abstract: Crupina vulgaris (common crupina) is an invasive annual plant of rangelands and pastures in the United States. A leaf-spotting fungus, Ramularia crupinae, has been evaluated for biological control. There are two varieties of C. vulgaris which differ morphologically and biologically, particularly in requirements for bolting. A vernalization protocol enabled synchronization of bolting, thus facilitating comparative studies of both varieties. Detached leaf experiments suggest that all leaves provide photosynthate for seed fill, but the cauline leaves, on a relative basis, are 5 – 10 times more important. Both varieties are damaged by the candidate pathogen. There were significant reductions in seed yield as the number of inoculations increased from 0 (controls) to 3. None of 35 taxa, i.e., species, cultivars, and varieties, in the Tribe Cardueae developed symptoms, except for the two varieties of common crupina. Best Linear Unbiased Predictors (BLUPs), generated by a mixed model analysis of disease reaction and genetic relatedness data indicated that only C. vulgaris varieties were susceptible to disease; BLUP estimators for common crupina were significantly different from zero. None of the other taxa, including an additional 26 that were not inoculated, had BLUP estimators that were significantly different from zero. Results suggest that R. crupinae is a good candidate for biological control of this important weed pest and would not likely affect other species of importance in the U.S.