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Sensitivity of Peronospora hyoscyami f. sp. tabacina to Carbon Dioxide, Compared to that of Botrytis cinerea and Aspergillus niger. A. M. Svircev, Graduate student, Plant Sciences Department, The University of Western Ontario, London, Ontario, Canada N6A 5B7; W. E. McKeen(2), and J. W. Berry(3). (2)(3)Professor, and graduate student, Plant Sciences Department, The University of Western Ontario, London, Ontario, Canada N6A 5B7. Phytopathology 74:445-447. Accepted for publication 3 November 1983. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/Phyto-74-445.

Carbon dioxide concentrations as low as 0.8% significantly reduced germination of conidia of Peronospora hyoscyami f. sp. tabacina. Most inhibited conidia germinated if they were returned to air after 2 hr of treatment with CO₂. Germ tubes produced by conidia while in the presence of increased amounts of CO₂ were morphologically altered. The mitochondria remained shrunken and the outer mitochondrial membrane remained contorted for a much longer time during germination in 3% CO₂ than during germination in air. Five and 15% CO₂, respectively, were required to reduce germination of Botrytis cinerea and Aspergillus niger significantly.