Effect of 02 on radial growth and sclerotial production. At 1% 02, average radial growth of isolate CSS-I after 48 hr was 7.5 mm; growth was increased to 32.5 mm at 4.1% 02, but further increases in 02 above 4.1% did not significantly increase growth (Fig. 1). Results from tests of other isolates were similar to those presented in Fig. 1.