Q What is pansy downy mildew?
A This disease is caused by the fungus-like organism Peranospora violae. It has only become a problem relatively recently, possibly encouraged by several mild winters that have allowed spore numbers to build up.
Caption: Downy mildew can prevent plants flowering as well as these
Q What plants does it affect?
A The disease is most often seen in bedding pansies and violas, but may attack related species including violets and wild pansies.
Q How do I recognise it?
A Growth of affected plants slows down and they look generally unhealthy. The surface of infected leaves turns pale green or yellowish, and they may roll down at the edges. Grey, downy patches appear underneath.
Q Could I mistake it for anything else?
A Pansies can also be affected by powdery mildew, but, with this disease, which is unrelated to downy Pansies and their relations are subject to several specific diseases including pansy downy mildew, pansy leaf spots and pansy sickness mildew, the grey patches are on the upper leaf surface and tend to appear in dry rather than wet weather.
Q What damage does it do?
A Badly affected leaves may die, so the disease is disfiguring and reduces flower production, though mature plants will usually survive.
Q What is its life cycle?
A Downy mildews can only grow and reproduce on living plant material where they produce spores, which can be carried in the air over very long distances. Otherwise they survive in the soil as resistant spores, which can be spread in plant debris, on shoes, tools and equipment, or with bought-in plants.
Q When do attacks occur?
A Attacks can occur at any time, but the disease spreads most rapidly in damp weather when plants are continually moist.
Q How do I control an attack?
A There are no chemicals available to gardeners to treat this disease. Picking o a ected leaves as soon as the problem is spotted may help to reduce the severity of an attack.
Q How do I prevent it in future?
A Always buy healthy, well-grown plants and do not overcrowd them. Do not soak the leaves when watering, water directly onto the soil. This is particularly important in containers, where plants will be more crowded than usual. Avoid replanting pansies in the same soil or potting compost to reduce the risk of spore numbers building up.