Q What are the symptoms of impatiens downy mildew?

A Affected leaves turn pale green, then yellow and may fall prematurely, leading to bare stems. A white growth develops on lower leaf surfaces and plants often become stunted. Flowers are often reduced in number or absent.

Caption: Affected plants drop their leaves

Q Are all impatiens affected by downy mildew?

A Downy mildew mainly affects cutting-raised impatiens. Downy mildew on seed-borne impatiens has not yet been found, but it can appear on both seed and cutting-raised material, as infection can cross over. It can also occur on wild species, such as garden balsam (Impatiens balsamina), from which the common impatiens bedding plant is derived. Severely affected plants may be killed before flowering and partially affected plants often lose their appeal. New Guinea impatiens aren’t affected and the 'Imara' range of impatiens promises resistance to the disease.

Q How do I control impatiens downy mildew?

A  Buy good-quality plants and check them regularly. If growing your own plants, sow from seed from a reputable source. Avoid overhead watering to reduce surface leaf moisture and the risk of infection. Ventilate greenhouses and space plants so air can circulate around them. Diseased plants should be removed and burnt promptly. Ideally, rotate bedding-plant displays so impatiens
aren’t grown on the same site year after year. Current fungicide options are limited, but the early application of a fungicide containing trifloxystrobin may give some control.