FIG 3.

Inhibition of conidial germination and germination tube elongation of F. oxysporum f. sp. pisi R2-238, F. oxysporum f. sp. pisi R5, and F. verticillioides T4-0 by pyrrolnitrin (A) and rhizoxin WF-1360F (B). Twenty hours after conidia of the Fusarium spp. were placed in antibiotic solutions, germination and germination tube elongation were observed under a dissecting microscope and photographed. The blurred regions visible in some photographs are propagules outside the depth of field of the microscope. Four replicate conidial suspensions were assessed for each antibiotic concentration, and the experiment was done three times with nearly identical results.