Gardeners looking to grow impatiens — those shade loving, colourful blooms — this summer will have to rethink their plans.

A strain of downy mildew disease has recently been found in the Fraser Valley and Vancouver, and is believed to be responsible for killing off these beloved garden plants. 

"It's literally annihilated this wonderful plant " said Jason Vandermay in an interview with CBC Radio's Rick Cluff on The Early Edition.  

downy-mildew-impatiens

The fungus has shown up sporadically since early 2000 in isolated areas of the U.S. but has been widespread in Europe since 2003 – this year it's showed up in Canada. (CBC)

Vandermay, the greenhouse and garden manager at Surrey's West Coast Gardens, says the economic impact of the mildew has been severe. 

"It's a major effect. We grow 6,000 flats of impatiens," said Vandermay adding it is the species Impatiens walleriana  — also known as "busy Lizzie" or "elfin impatiens" that has been affected. 

Before you head off to the nursery, here are a few FAQs about the mildew and its effects. 

What is downy mildew? 

There are several types of downy mildew, each of which attacks a particular type of plant. Impatiens are being attacked by a type of downy mildew called Plasmopara obducens.

It appeared several years ago in Europe, showed up in the U.S in 2011, and has now most recently been found in Canada over the last year. Weather partly to blame because the the mildew thrives in cool, wet conditions.

How do I know if my impatiens have been affected? 
It starts off slowly, causing leaves to curl downward, but eventually they turn yellow and fall off and the lush impatiens are transformed into bare stalks. 

How does the disease spread? 
Unfortunately, there is no cure. Fungicide applications aren't effective and should you see signs of the disease, immediately remove the whole plant, roots and all and place it in a sealed bag for disposal. 

Are all impatiens susceptible to the mildew? 
No. Only Impatiens walleriana are affected. Other types, like New Guinea or Sunpatiens have not been affected. 

Can I plant impatiens next year in soil that once grew infected plants? 
General consensus is to avoid replanting impatiens in the same area, as the spores are still active, but since the disease is specific to Impatiens walleriana, you can grow other bedding plants without risk. 

Impatiens are a staple for shady areas. What else can I plant as a substitute?
There are lots of alternatives!  Shade annual plants with colourful foliage include, caladium, begonias, coleus, hypoestes and iresine.