Penetration assay with B. bassiana ATP-02. Spray formulations with (n = 7) and without (n = 2) B. bassiana (Bb) were brushed onto the leaf tips. (a) Microscopic detection of Bb in a cross-section of a leaf mid rip from a Bb-treated leaf at 200-fold magnification. The arrow marks the hyphae in the leaf tissue. (b) Bb was detected in the untreated area of the Bb-treated leaves by PCR and subsequent gel electrophoresis. Lane 1–5: DNA from Bb-treated leaves; Lane 6: Bb DNA from pure SDA culture; Lane 7–8: DNA from control-treated leaves; Lane 9: no template control; Lane 10: 100 bp DNA ladder (AppliChem GmbH, Darmstadt, Germany).