Impatiens affected by downy mildew blight

Duane Campbell
Duane Campbell

How’s your impatiens doing this year? Yeah, mine too. If you liked tomato late blight a couple of years ago,you’re going to love impatiens downy mildew.

The good news is that though late blight devastated back yard tomato plants in 2009, it was largely gone the next season. It can’t survive our winters. The bad news is that impatiens downy mildew can. It lingers in plant debris in the soil or blows in from miles away. If your impatiens all died this year, you can pretty much count on that happening again next year.

This particular strain of downy mildew is new. It was first reported as a serious problem in landscapes last year in the upper mid-West. This spring it hit the Northeast. Hard. While it is often called a fungus, it isn’t quite. The details are boring, but it is something scientific types call “almost a fungus.” Which to us non scientists sounds like being almost pregnant. In any event, fungicides don’t help much in the home landscape.

Since this is a new infestation, there are conflicting reports, but for those who plant impatiens acre by bilious acre, your life is over. For the rest of us, there is good news, and perhaps even better news.


The good news is that this is a very fussy fungus, or almost fungus. The only thing it is interested in is Impatiens walleriana, the common garden impatiens. New Guinea impatiens and the newer sun-patiens are unaffected. You could plant them as a replacement. Nor does it care for anything else in your garden.

The very good news is that perhaps for the first time in years you are going to have to put some thought into your garden. Impatiens is cruse control. Now you have to take the wheel.

The first thing to keep in mind is that though impatiens is commonly called a shade plants, I have most often seen then planted and thriving in part sun. Part sun means that they get some direct rays in the morning, maybe in the late afternoon, but have protection during the middle of the day. There are lots of flowers that love that.

If you have a row of impatiens,the first substitute that comes to mind is wax begonias. While I have a strong monochromatic penchant, a mix of red, pink, and white begonias has its charm. And the pinks are more civilized than the Pepto Bismol shades in impatiens.

Coleus has made huge strides since it changed its name to Solenostemon (which I can neither remember nor pronounce, so I’m sticking with coleus). The new ones are large and stout, almost shrubby, with much better colors. Two of my favorites right now are Henna and Marooned. They tend to be expensive, but all of them root easily to fill large spaces from one purchased plant.

The same dramatic revolution has happened with coral bells. It started three decades ago with Palace Purple. Over the years breeders developed metallic shades and dusky reds. More recently there has been a color explosion with heucheras in lime and gold and bronze and even almost real red, real enough by horticultural standards. Best of all, they are perennial, so no more trudging every spring through the big box parking lots for yet another tray of impatiens.

And brunneras, the false forget-me-not, like Jack Frost and Looking Glass. And callas, if you think you really like planting things every year. Or hellebors or bleeding heart or primulas or … lots of things. I’m thinking that maybe impatiens downy mildew has done us a favor.

Duane Campbell is a nationally known agricultural expert. He can be reached at R6, Box 6029, Towanda, PA 18848 or e-mail