Brown spot. Leaf spots circular up to 1 cm or more diam., brown, becoming zonate and surrounded by a yellow halo. Occurs mainly on older leaves, but also infects seedlings.
Morphology
Conidiophores arising singly or in groups, pale olivaceous brown, up to 80 µm long, 3–5 µm thick, with one or more distinct conidial scars. Conidia sometimes solitary but usually in chains of up to 10–15 or more, sometimes 1–3 branches of 1–7 conidia, straight or slightly curved, obclavate, ovoid or narrowly ellipsoid, body of conidium 12–35(–48) µm long, 5–12(–14) µm wide, pale to mid brown, smooth or verrucose, 3–8 (commonly 5–6) transverse septa, 1–2 longitudinal or oblique septa, constricted at septa; apical secondary conidiophore 1-celled, 3 × 3 µm.
Notes
This species has been often mistaken for Alternaria alternata.
