Effects of the Phomopsis convolvulus Conidial Matrix on Conidia Germination and the Leaf Anthracnose Disease of Field Bindweed (Convolvulus arvensis). Salvatore A. Sparace, Associate Professor, Macdonald College of McGill University, 21111 Lakeshore Road, Ste. Anne de Bellevue, Québec, Canada H9X 1C0. Lee A. Wymore, Rima Menassa, and Alan K. Watson. Postdoctoral Research Associate, Research Assistant, and Professor, Macdonald College of McGill University, 21111 Lakeshore Road, Ste. Anne de Bellevue, Québec, Canada H9X 1C0. Plant Dis. 75:1175-1179. Accepted for publication 31 May 1991. Copyright 1991 The American Phytopathological Society. DOI: 10.1094/PD-75-1175.

The conidia-free conidial matrix of Phomopsis convolvulus contains 6% dry matter which consists of approximately 89% carbohydrate and lesser amounts of protein and free amino acids. Conidia densities of 10⁶ per milliliter or greater in the presence or absence of matrix are unable to germinate without dilution. Increasing concentrations from 0 to 5% (v/v) of conidial matrix in water reduces conidia germination from 70 to 11%. Conidia survival in terms of percent germination was greatest (80–100% for up to 9 wk) when conidia were stored at room temperature in the presence of liquid matrix, whereas drying was generally lethal to conidia. The matrix had no effect on the initiation and subsequent development of the leaf anthracnose disease of field bindweed as measured by dry weight accumulation of treated plants. The undiluted conidial matrix of P. convolvulus functions to prolong conidia viability and prevent germination of diluted fresh conidia.