FIG. 1.

(a) Spores of S. castanea observed in incident light under a binocular microscope. C, cloudy spores; H, healthy spores with vacuolate content. (b) Crushed healthy and cloudy spores. (c) Control for surface sterilization. V8 agar medium plates contain either a Leptosphaeria sp. suspension or 10 spores of S. castanea per plate. Five sterilization solutions were used, consisting of 4% to 12% chloramin T, 0.02% streptomycin, and 0.01% gentamicin. Sterile distilled water (0%) was used as a control. The Leptosphaeria sp. only grew in the control treatment (0%). L, Leptosphaeria sp. suspension; F, fungal colony; B, bacterial colony. (d and e) Leptosphaeria sp. isolated from healthy S. castanea spores. The mycelium comprises septate yellow-brown hyphae (Hy), and the fungus also forms black pycnidia (P) which contain conidia (Co).