Black leaf spot. Circular, zonate spots up to 1cm diam., generally darker than those caused by A. brassicae. May cause damping-off when infected seed is sown.
Morphology
Conidiophores arising singly or in groups of 2-12, pale to mid olivaceous brown, up to 70 µm long, 5-8 µm thick, usually unbranched, with one or more distinct conidial scars. Conidia in branched chains of up to 20, straight, cylindrical, tapering slightly towards the apex, or obclavate, 18-130 µm long, 8-20 µm wide, pale to dark olivaceous brown, smooth or slightly warted, 1-6 (-11) transverse septa, 0-6 longitudinal or oblique septa (sometimes 2 longitudinal septa in one segment), constricted at septa, basal scar not very obvious; apical cell functions as a secondary conidiophore and usually bears a conidial scar.
