Monday, July 15, 2013

Impatiens Downey Mildew Update

The information I pasted below is an excerpt from an online newsletter called ‘Acres Online’, put out by Ball Publishing. If you are interested in receiving the full copy for yourself go to

Downy Mildew update: Spring 2013

Despite being known in the U.S. since the late 1800s, impatiens downy mildew (IDM) didn’t rear its ugly head in landscape plantings until a couple seasons ago. And in 2012 it was devastating in pockets of the country. So how has the 2013 season been when it comes to our beloved impatiens?

First, IDM did impact production numbers. Best as I can gather from my contacts, wholesale seed and plug sales were down around 30% from 2012.

As for the disease itself, I checked with Ball’s plant pathologist Colleen Warfield for a landscape update. According to Colleen, the disease is still active in Florida, confirmed in Hawaii, and it’s been found recently in San Diego County. However, in the Eastern U.S., there has only been one confirmed report of IDM on I. walleriana in the landscape, and that was in late May. And there is an unofficial report from an Internet blogger who just found it in her Ohio garden. But so far, there are no other confirmed reports on regular impatiens. However, there have been a couple of reports of IDM on I. balsamina, a naturalized plant better known as spotted snapweed or garden balsam. That’s bad news, since we now know of a second host plant.

For the very latest update, Colleen and Margery Daughtrey will be presenting “Impatiens Downy Mildew—Are We Any Closer to Control?” at the Short Course on Saturday, July 12 from 10:45 to noon in room E170. Be there!

Is it in your area? Remember, just because your impatiens have some yellow leaves doesn’t mean it’s IDM. Look for the presence of white sporulation (down) on the underside of the foliage. If you think you’ve seen it in your landscape, let Colleen know at