Alternaria brown spot attacks young fruit, leaves and twigs, producing brown-to-black lesions surrounded by a yellow halo. The halo is caused by a fungal toxin which rapidly kills tissue. Leaf lesions are generally circular but will often have a tail, following the leaf vein which gives the lesions an eye-spot appearance. The necrosis extends along the veins as the toxin spreads in vascular tissues. On young leaves, lesions can appear as early as 36-48 hours after infection. Lesions enlarge as leaves mature and can vary in size from 1-10 mm (0.04-0.4 inches) and will be larger if the infection occurred earlier in the season. If Alternaria brown spot is severe, the leaves may drop and entire shoots can wilt and die.