|Bruckart, William - Bill|
Submitted to: International Symposium on Biological Control of Weeds
Publication Type: Proceedings
Publication Acceptance Date: 2/14/2011
Publication Date: N/A
Technical Abstract: Common crupina (Crupina vulgaris) is an annual plant of major importance in the Western United States. There are two varieties of crupina, i.e., var. vulgaris and var. brachypappa that occur in North America. Only by artificial plant vernalization, is it possible to synchronize bolting between varieties for comparative studies. Successful vernalization was achieved in this study by germinating seeds and growing transplants at 10 C with an 8 hour photoperiod for a minimum of one month. Typical plant phenological development, i.e., seedling, rosette, bolt, bud, flowering, and seed stages, results for both varieties. Use of this protocol has enabled comparative studies on susceptibility of both varieties at the same time. Because crupina reproduces only by seed, attempt was made to determine which plant part or (parts) provide photosynthate for seed fill. If such can be identified, then climatic conditions that occur at that stage of growth can be estimated and used to determine if conditions would be favorable for disease when the plant is most vulnerable. Either selected leaf removal or inoculation by Ramlaria crupinae of various plant parts or stages of growth was used in these tests. Clear evidence of the importance of cauline leaves was found in two leaf removal experiments. Although reductions in seed yield and other parameters resulted from inoculations with R. crupina, the importance of plant part was less clear than in the detached-leaf experiments. One reason for this difference is that symptom development under greenhouse conditions requires from 10 days to 2 weeks, so the effect from infection yield parameters in crupina may be slower to develop than when leaves are detached. Although R. crupinae is damaging and does cause seed yield loss, more profound effects may result from inoculations at earlier stages of development of after multiple inoculations.