FIG 3.

Numbers of Fusarium graminearum perithecia produced per square centimeter of maize stalk (A), frequency of mature perithecia (B), and cumulative numbers of mature ascospores in perithecia (C) as affected by constant relative humidity (RH, indicated on the right, in percentages) and days of incubation. Maize stalks were sterilized, inoculated with F. graminearum conidia, and incubated at constant RHs. Maturity was evaluated by microscopic observation of crushed perithecia. The numbers of mature ascospores were determined by suspending perithecia in water and counting the ascospores in the suspension with a hemocytometer; the average numbers of ascospores per perithecium were then calculated. Points are the averages and whiskers the standard errors of 40 values (2 experiments, 2 replicate trays with 10 stalk pieces each).