Susceptibility of various accessions of Convolvulus arvensis to Phomopsis convolvulus

The susceptibility of Convolvulus arvensis L. accessions from different geographic locations to disease caused by the fungal pathogen, Phomopsis convolvulus Ormeno, was evaluated. In a postemergence application experiment, single excised plant shoots of C. arvensis collected from 11 different regions in North America and Europe were inoculated with P. convolvulus conidia. All C. arvensis accessions showed similar disease reactions. However, plants originating in Canada (Quebec) and Spain showed significantly greater disease development than plants from a USA accession (Montana). In a separate preemergence application experiment, plants from two selected accessions originating in Greece and the USA (Montana) were grown from root stock and subjected to a granular formulation of P. convolvulus applied to the soil surface. The emerging shoots of both accessions showed severe disease development and the fungal application on Greek and Montana accessions reduced above-ground biomass 83 to 100% and 65 to 86%, respectively. Results of this study indicate that control of C. arvensis using P. convolvulus might be achieved in various geographic regions.