Foxglove is a biennial flower grown as a perennial that is covered in trumpet-shaped blooms in spring, according to the Michigan State University Extension. Digitalis purpurea, or foxglove, is generally easy to grow, but can fall victim to a few diseases.
Gray mould -- Botrytis -- causes brown lesions on leaves. According to the University of Illinois Extension, infected leaves also emit a grey dust when disturbed. The disease can cause all parts of foxglove to die back. The best control method for grey mould is to keep the planting area clean, because the disease breeds in dead plant material, according to the University of Illinois Extension.
Anthracnose is caused by an airborne fungus that creates purple-brown spots on leaves. The spots start out small, but grow to 1/8 of an inch in diameter. According to the Oregon State University Extension, the condition can be prevented by not planting foxglove close together and avoiding overhead watering. There are also chemicals treatments available.
Verticillium wilt is caused by soil-borne fungi. The disease disrupts the flow of water from the roots to the foliage, causing leaf wilting, yellowing and eventual death. The University of Illinois states that this condition can be prevented by rotating crops, controlling weeds and keeping plants healthy so that they can fight off the fungi.