Dark Leaf Spot

This disease produces leaf spots that vary in size from pinpricks to 12mm in diameter. These spots, which develop on the lower leaves, begin as small circular yellow areas. They enlarge in concentric circles and become dark in colour, with various shades from brown to black. The spots may be surrounded by chlorotic halos and severely affected leaves turn yellow. With ageing the centre of the spot becomes thin and papery and may fall out giving a "shot-hole" appearance.

On sprout buttons the symptoms are discrete small dark brown spots which can extend through several leaf layers of the button.

On cauliflower the disease can cause a brown rot of the curd.

The disease is spread from growing crops or debris by windborne spores. The disease is favoured by warm moist conditions.