Impatiens downy mildew - Plasmopara obducens

July 8, 2014 – 05:26 pm

How to recognise it

Leaves become mottled and yellow, then fall. You may find a fine, white fungal growth on the underside of the leaves, however they may decay so quickly the fungus doesn’t have time to develop into this form. Flowers are often shed so the stems are left bare except for the odd flower bud. Often the plant will die completely.

Why it’s a problem

This serious disease of Impatiens will weaken and, often, kill plants. It spreads from plant to plant quickly and easily. Entire bedding displays can be destroyed within a week and the disease will persist in the soil for up to 10 years.

Where you are likely to find it

Found on Impatiens bedding plants (busy Lizzies). It mostly occurs in spring within glasshouses and in summer outdoors. Most likely to be found during/after periods of wet weather.

To date the New Guinea impatiens, Impatiens × hawkeri, appears to be immune to the disease.

How to prevent it

Raising your Impatiens bedding from seed will reduce the risk of an infection from bought plants, although there is still a risk that airborne spores will reach your seed grown plants. Currently no resistant cultivars are available.

In glasshouses ensure that you have good ventilation and only water the plants from the bottom, so the leaves don’t get wet.

Ensure that plants aren’t grouped too close together, to ensure good airflow between them.

How to get rid of it

Remove any affected plants and destroy them (eg by burning), do not put them into compost. Do not re-plant an affected area with Impatiens bedding for at least a year, if possible more (the spores may survive in the soil for up to 10 years).

If the plants were grown in containers throw away the potting compost (again, not into a compost heap) and thoroughly disinfect the container before using it for Impatiens plants again.

Is it good for anything?!


Other useful information

Other plants can be grown in soil that has been infected, it appears that the disease only infects Impatiens plants. Bedding begonias, for example, aren’t affected.


Creature Comforters Impatiens Bach Flower Remedy 30ml. Genuine Traditionally-Made Remedies. Large 30ml Flower Essence Practitioner bottle
Health and Beauty (Creature Comforters)
  • Made to the Traditional and Trusted Methods of Dr Bach - Direct from the Mother Tincture
  • For: Impatience / Irritability / Frustration / (Pain)
  • To help encourage feelings of: Patience / Tolerance / (Ease)
  • Gentle help for emotional problems - naturally. Suitable for all ages.
  • Premium quality Bach Flower Remedy. Large bottle - perfect for Practitioners. Direct from the birthplace of Bach s Remedies in England

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Advice on getting rid of bugs on my impatiens

Today I just noticed bugs on my impatiens. They look just like miniscule coffee grounds. They are black, round, don't move, and they disintegrate into the air when I brush them off. The tops & undersides of the leaves and flowers are not destroyed in any way. No holes in the leaves, no dying plants. I did at first think they were coffee grounds however there is no way coffee grounds could get there. If it makes a difference, my plants are in a window box. I have just clipped all the leaves and flowers back :( and would like to buy a remedy that kills this bug. Any ideas of the bug--and the remedy? They are not aphids

Bach Flower Essences Impatiens, 20 ml ( Multi-Pack)
BISS (Bach Flower Essences)
  • Hornbeam (Carpinus betulus) is a flower essence for mental weariness, having that Monday morning feeling, difficulty dealing with problems, and doubting abilities

Horticulture 2008 Horticulture Annual CD
CE (Horticulture)

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