Updated information on Impatiens Downy Mildew for 2015 onwards! Busy Lizzy bedding plants are back on sale in reputable garden centres in the UK. So far the plants are showing no signs of the mildew and it looks as if we can have our favourite little bedding plants back on our patios again this summer!
For archival purposes I’m leaving the rest of this blog post on here though for now it is out of date.
Did you buy Busy Lizzy bedding plants a few years ago? Did they grow well for you or did they develop a white fuzz on the underside of the leaves? Then did the leaves turn yellow, drop off and leave you with just the stems and a few unopened flower buds? Well if you were one of those unfortunate gardeners then you were not alone as the common Busy Lizzy Impatiens walleriana is in a state of crisis due to Impatiens downy mildew.
We all love our summer flowering plants
but I lost count of how many plants I saw develop this disease. Along with complaint after complaint from fellow gardeners. It was due to the airborne organism Plasmopara obducens.
There was nothing we could do to treat the plants. The mildew spores had finally built up resistance to the one fungicide (metalaxyl) that used to keep it under control in commercial nurseries.
Impatiens Downy Mildew was first found in the UK on the imported cutting raised plants in 2003. It then spread rapidly to the seed raised stock. So it didn’t matter where you bought your bedding plants from. Garden centre, nursery, big shed or supermarket plants all developed the mildew which remains in the soil for up to a year. Mildews might all look the same on different plants. But each mildew pathogen is unique and this particular mildew cannot spread outside of the Impatiens family.
|Impatiens walleriana last grown in my garden in 2010
Discussions were held with The Horticultural Development Council ( HDC), British Protected Ornamentals Association ( BPOA), and the Horticultural Trades Association ( HTA). They made an industry joint decision that this plant shouldn’t be sold in the UK for the foreseeable future.
So alas in 2012 the common Impatien walleriana variety became be absent from most containers, borders and hanging baskets. Likewise major retailers and seed companies joined the quest in trying to eradicate this mildew.
What might shock you is what Peter Cook told delegates at the Garden Centre Association conference in 2010 down in Oxford when he said that it could be “a 25 year journey” to find the cure! Just think of it – that could mean a whole generation of gardeners missing out on these colourful summer bedding plants.
Edit to add: Now that we’re into 2014 this advice still is the same – reputable nurseries and garden centres will not be selling this plant.
So what can we grow instead?
Firstly it’s only the common Busy Lizzy Impatiens walleriana that has been affected by the disease. The New Guinea Impatiens – Impatiens × hawkeri, Himalayan balsam and Impatiens glandulifera have been unaffected.
You’ll probably find that most nurseries,garden centres and online retailers will be offering a new type of impatien. It’s called DIVINE – Impatien hawkerii F1 ‘Divine mix’. The plant is highly tolerant of the downy mildew. Furthermore it has a larger flower form and better uniformity than the common impatien. Moreover it grows in shade and semi shade though can do well in sunnier conditions if kept well watered.
|Lavender Impatien ‘Divine’ I’ll share my own photos of the flowers by the end of April….weather depending!
- Plant 8 inches apart
- Height 10 inches approx
- Spread 12 inches approx
- Blooms all summer
- Deep green leaves
|Impatien hawkerii F1 ‘Divine mix’ both photos from Panamseed.com
The RHS are advising gardeners to buy other plants instead of Busy Lizzies like begonias and fushias. These are good alternatives for the problem shady areas that the Busy Lizzy once thrived in.
Finally if you do grow some Impatiens that you’ve raised as cuttings from your own plants check them weekly. If they start to show any combination of the the following signs the RHS advise that you dig them up. You can either burn or bury them deeper than 20 in (50cm) including some of the soil surrounding the plants.
Here are the signs of Impatiens Downy Mildew
- White or grey fuzz on the underside of the leaves
- Leaves start to curl downwards
- Leaves start to grow in a distorted fashion and are small and pale
- Flower buds fail to open
- Leaves fall of plants
Were you affected by this type of mildew?