Impatiens Downy Mildew

Impatiens walleriana Mix

The Sky is Falling – Impatiens Downy Mildew

Impatiens wallerianaYou might have heard rumors that there is something out there bent on killing our impatiens.  It’s not the end of the world, it is not an alien attack, it has nothing to do with politics, it is a not the plant version of Avian Flu, it is just a fungus that has the POTENTIAL to impact our gardens by killing impatiens. Not all impatiens are affected however, only impatiens walleriana, which are the most common type that is a staple in many of our shade plantings.

There is a lot of mis-information or
partially correct information floating around.  Let’s talk first about some basics.

  • What is this disease?  It isn’t a virus, it is a fungal disease called downy mildew.
  • Where could your plants contract the disease? While the plants at a garden center could have the disease, it is just as likely that those plants COULD (not will) contract it after you plant them in your garden.
  • If I plant Impatiens are they destined to die?  From cold temperatures yes, but there is no guarantee that you will have issues with this fungus.  Downy mildew is predicted to be problematic in some parts of the country this year, as it was last year. How likely you are to have issues is at least partly dependent on where you live.
  • When will my plants get the disease/how long will my impatiens live?  There is no timetable for when or if your impatiens might get downy mildew or for how long it would take them to die IF they do become infected. 

What can you do?

Well, not a lot except know not to buy infected plants, that then infect your garden. Your best local resources are your county UW Extension agent who can give you a better idea of how much of a problem downy mildew is likely to be for your area and your local independent garden centers who are extensively monitoring for this fungus and will be able to direct you to disease free plants or other alternatives.

How do you know if plants are infected?

Plants will start to lose their lower leaves and when you turn the leaf over and look at the bottom it will be dusted with what looks like white flour. If you see that at all – don’t buy any impatiens!  Buy something else.  If your impatiens are already planted and you see this developing, pull them out and dispose of them in a plastic garbage bag.  Do Not Compost Them.  The fungus lives in the soil and requires commercial grade fungicides to eradicate it.  Next year don’t plant impatiens walleriana in or near those locations, the new plants may become infected.Infected Impatiens plants loose their leavesUnderside of an infected impatiens leaf

What can I buy instead?

Here are 7 great options for replacing Impatiens in your shade gardens this summer

New Guinea Impatiens:New Guinea Impatiens

The simplest switch is to use New Guinea Impatiens which are not susceptible to Downy Mildew.  Easy to grow and larger flowered than traditional impatiens, they have great summer performance and are available in a wide variety of colors (reds, pinks, white, purple, orange, coral).  They can even tolerate slightly sunnier locations than the traditional impatiens.

Colorblaxe ColeusColeus:

With all the emphasis on getting sun loving coleus for the home gardener, do not forget that these plants are easy and provide season long color for the shade as well! Excellent in mass plantings or to highlight other shade flowers, the series has distinctive colors, shade performance and do not bloom until late in the year, if at all.  For more ideas how to use coleus check out the article 2015: Year of the Coleus

Torenia: Summer Wave Torenia

The entire series of Torenia make great partial shade color and mix well with all the other shade annuals. These provide the trailing component of mixed containers and baskets as well as constant color through the summer. They are heat and humidity tolerant, disease resistant and easy to grow.  When planted in a container they will cascade over the side and when they are planted in the ground they will spread out and create a blanket of lovely flowers.

Oxalis: Oxalis, Shamrock

Trouble free and easy to grow, these clovers make wonderful shade plantings in both containers and the landscape. Dark foliage and small white flowers provide long shelf life for retailers with consumer success and are very tolerant of shady conditions. Whether Proven Winners® or Proven Selections®, Oxalis makes a great unique addition to the shade garden, whether in the ground or in containers.

Heuchera and other  Perennials and  Shrubs:

Don’t forget all the great shade perennials we offer, the Dolce® Series being the most well-known; great vibrant colors,  tolerant of moist and dry shade, and they are trouble free for gardeners.  Don’t stop there; Hosta, ‘Bottle Rocket’ Ligularia, ‘Color Flash’ Astilbe, ‘Northern Lights’ Azaleas, and a huge variety of Hydrangeas are also great shade performers in a shady spot.  Rocket LigulariaAstilbe Color FlashCombination of Heuchera Varieties

Fuchsia: Gartenmeister Fushcia

More often thought of as a plant for containers, some Fuchsia make good garden plants too.  Try the ‘Gartenmeister’ Fuschia, an upright growing plant that has dark green and purple foliage and striking flowers that hummingbirds love!

Begonias!

We have a great portfolio of Proven Selections® cultivars. After new guinea impatiens, Begonias are likely going to be the fastest growing market sector to fill the gaps in shade gardening.  With the Big, Nonstop® and Illumination® lines and all the other great begonias we offer you should be able to find a great palette of replacements for impatiens in areas affected by the disease.

Reiger, Whopper and Santa Cruz Begonias

The real secret here is not focusing on what might not be  available but what IS available.

In the plants listed here alone, there are tons of colors and textures, for landscape, containers or hanging baskets. Use downy mildew an opportunity to try a new slate of great plants for shade gardening.  This can simply be an opportunity to try something different, and potentially more interesting, in your shade garden!

The Sky is Falling-Impatiens Downy Mildew is an article created for Proven Winners by Rick Schoellhorn.  View the original article here.

toddmonge@custom-landscaping.com

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