A Foliar Disease of Field Bindweed (Convolvulus arvensis) Caused by Phomopsis convolvulus. J. Ormeno- Nuñez, Graduate Student, Department of Plant Science, Macdonald College of McGill University, 21111 Lakeshore Road, Ste-Anne-de-Bellevue, Quebec, Canada H9X 1C0. R. D. Reeleder, and A. K. Watson. Assistant Professor, and Professor, Department of Plant Science, Macdonald College of McGill University, 21111 Lakeshore Road, Ste-Anne-de-Bellevue, Quebec, Canada H9X 1C0. Plant Dis. 72:338-342. Accepted for publication 4 November 1987. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/PD-72-0338.

Phomopsis convolvulus was identified as the causal agent of leaf spots and anthracnose lesions on field bindweed (Convolvulus arvensis). Seedlings (10–14 days old) were killed after spray inoculation with alpha-conidia concentrations of 5 × 10⁶ spores/ml or more. Increasing inoculum concentrations from 1 × 10⁵ to 5 × 10⁶ spores/ml resulted in decreases in foliage dry weight. At 20 C, a dew period of more than 3 hr was required before seedling death occurred or before significant reductions in dry matter were evident. The dew period following inoculation could be delayed for up to 48 hr without significantly decreasing disease ratings. Shoot regrowth occurred, however, when the delay was 24 hr or more. Disease severity and mortality following 24-hr dew periods were greater when dew period temperatures were at 20 or 30 C than when at 10 C. When plants were exposed to various temperatures (10–30 C) after a 24-hr dew period, no differences in disease severity were evident. These results suggest that this fungus has potential as a mycoherbicide.

Keyword(s): biological control, Convolvulaceae