- Worldwide distribution. On plants in the cabbage family, especially Chinese cabbage and mustards. Important fungal disease, similar to cabbage black leaf spot (see Fact Sheet no. 133).
- Damage: (i) seed infections cause pre- and post-emergence damping-off (see Fact Sheet no. 47); (ii) seed infection; and (iii) spots on head and/or outer leaves unsightly reducing quality and shelf life.
- Grey leaf and stem spots, circular or irregular, mostly between veins, up to 25 mm diameter, with concentric rings, producing spores below. Centre of spots fall out with age.
- Dark, sunken rots occur on heads of broccoli and cauliflower.
- Spread by water splash, in wind-driven rain, on seed.
- Cultural control: seed - hot water (50°C for 25-30 minutes; nursery hygiene: clean trays, pasteurise soil or use soilless mixes, and discard infected seedlings; weed; space plants to allow air movement; avoid overhead irrigation; collect and destroy debris after harvest; crop rotation.
- Chemical control: seed - captan or thiram; field - chlorothalonil, copper or mancozeb.
