Q What are pansy leaf spots?
A A variety of fungi cause spots on pansies and violas, particularly winter-flowering varieties. Large, disfiguring black spots are likely to be caused by Mycocentrospora acerina; brown, scorched spots by Ramularia agrestis; and dark, greasy-looking spots with brown centres by Ramularia lactea.
Caption: Leaf spot tends to occur in mild, moist conditions
Q What plants do they affect?
A These fungi can affect pansies, violas and violets, including wild species. Mycocentrospora also affects other genera, causing leaf spotting on a wide range of flowering plants, and root rot in carrots, parsnips and celery.
Q How do I recognise them?
A Leaf spots appear as distinct, separate spots, whereas mildews create more irregular patches of discolouration.
Q What damage do they do?
A Mycocentrospora can kill plants by rotting the crown. The other infections are generally confined to the leaves, so are largely cosmetic.
Q What is their life cycle?
A While growing on the pansies, the fungi produce spores, which are generally spread by rain or in surface water. They can also produce resting spores that can survive for many years in dead plant remains in the soil, ready to infect new plants.
Q When do attacks occur?
A Leaf spots are most likely to develop in mild, moist conditions. The spores do not travel far, so infection will generally come from wild pansies or violets nearby, or from soil or compost where pansies have been grown before.
Q How do I control an attack?
A Several general, systemic fungicides are approved for use on pansies and should help to control leaf spot diseases if applied when symptoms are first seen. These are myclobutanil, sold as Fungus Clear Ultra Gun (spray) Fungus Fighter Disease Control (spray) and Systhane Fungus Fighter (concentrate), and triticonazole, found in Scotts Fungus Clear Ultra (concentrate).
Q What are the organic options?
A Removing badly affected leaves will check the spread of the problem.
Q How do I prevent it in future?
A Inspect plants carefully before buying to check there are no signs of leaf spot, or grow your own from seed. Avoid growing pansies or violas in soil or compost that has been used for them previously.