Atmospheric ions and germination of uredospores of Puccinia striiformis.

Atmospheric ions, identified by mobility characteristics, were associated with germination of lyophilized uredospores of Puccinia striiformis West. at Bozeman Montana. Ions of intermediate size were highest in concentration, and percentage germination of spores was lowest during periods conducive to air pollution. In duplicate experiments at an isolated site near Barrow. Alaska, essentially all atmospheric ions were small ions and the fungus spores were consistently germinated near maximum.