In vitro electrochemical detection of nitric oxide (NO) in Botrytis cinerea strain B05.10. Samples were incubated for 12, 14, 16, 17 and 20 h. The arrow indicates the addition of 1 mm 2‐(4‐carboxyphenyl)‐4,4,5,5‐tetramethylimidazoline‐1‐oxyl‐3‐oxide (cPTIO) to the sample incubated for 20 h. The sterile culture medium B5S/SP (Gamborg's B5 salts medium supplemented with 10 mm sucrose and 10 mm KH2PO4; pH 6.0) (no mycelium) was used as a negative control.