Disease that’s killing impatiens may return for years; no treatment exists

September 4, 2012

impatiens early signs downy mildew disease Margery Daughtreyby Connie Oswald Stofko

If you had problems with your impatiens this year, the good news is that you probably didn’t do anything wrong.

The bad news is that your impatiens were probably killed by a fungus-like disease called downy mildew.

The disease remains in the soil, so you should plan on planting something different in that spot next year. impatiens around tree before downy mildew disease Margery Daughtrey

There is no treatment.

“That’s the most challenging thing about it,” said Margery Daughtrey, senior extension associate with Cornell University who co-wrote a fact sheet on the problem.. “There’s really nothing a home gardener can do about it. There is nothing to spray, nothing to buy to counteract it.”

The plants will seem fine, then they turn yellow, drop their leaves, drop their flowers and even drop their stems, Daughtrey explained. The photo at the beginning of this story shows the early stages of the disease.

The effects are most dramatic after rainfall because the disease flourishes in moist conditions. Daughtrey’s before photo, above right, was taken last summer in Riverhead, which is on Long Island, then the area was drenched in a hurricane and a tropical storm. The after photo, below right, was taken five weeks later in mid-September when the impatiens should have been happily blooming. Many gardeners incorrectly assumed their plants were damaged by the severe weather.

Our dry summer here may have spared us to some degree from this problem, she said, and the problem may get worse as we experience wetter weather. The disease has already been reported in the Snyder and Williamsville areas of Amherst, said Mark Yadon, vice president at Mischler’s Florist and Greenhouses.impatiens after downy mildew disease Margery Daughtrey

There are many things that can make an impatiens plant turn yellow and have stunted growth, such as lack of water or fertilizer. However, those problems don’t usually cause it to drop its leaves, Daughtrey said.

If your plant lost its leaves, you probably have the downy mildew problem. Check the undersides of the leaves. Affected plants will have a white coating that looks sugary, as in the photo below left.

Daughtrey noted that it’s not always easy to see the coating. You may not spot it on every leaf of an affected plant; you may have to check many leaves before you detect it. Also, note that the undersides of many impatiens leaves are normally a mottled purple. If you see mottled purple, don’t worry.

If your plants are affected, pull them up, bag them and throw them out. Don’t put them in your compost!

The disease is expected to come back next year.

Because this is a new disease, it’s hard to know how it will play out in coming years, Daughtrey said. It may be worse in rainy years and better in dry years. It could rage through an area for a few years, then calm down for reasons we don’t understand.

impatiens with white coating from downy mildew disease Margery DaughtreyThe disease affects Impatiens walleriana,  which are  standard garden impatiens including double impatiens and mini‐impatiens.

However, the disease doesn’t affect New Guinea impatiens, which may do well in the spot where you would ordinarily have impatiens.

Yadon from Mischler’s noted that New Guinea impatiens are more expensive to produce than standard impatiens, so gardeners who want to fill in a large area may be looking for less expensive plants.

Begonias are a good replacement for impatiens, he said, but you won’t get the same color range. You can find begonias in reds, whites and pinks, but you won’t get the salmon, purple and lavenders.

Coleus can add color to a shady area, though it’s not a flower. Other options are flowering vinca, ornamental grasses and tropical foliage plants.

No one knows why this disease, which has existed in the wild since the 1800s, is now bothering impatiens, Daughtrey said. Impatiens have been around since the 1960s and are a favorite of gardeners because they offer bright colored flowers for shady areas.

Now that impatiens is a less reliable plant, they will become less popular, Daughtrey predicted, which means a big change in direction for growers. She estimates that impatiens constitute 20 to 70 percent of what businesses in the bedding plant industry produce.

“It’s going to be devastating– impatiens is a huge crop,” Yadon agreed.

Yadon said he probably will still grow impatiens next year, but will create good signage explaining the disease problem. A plant can leave the garden center perfectly healthy, then fail when it is in the garden because the disease organism is in the soil and can be spread by the wind.

“We’ll be looking at other things to produce,” Yadon said. “We have to figure out something else to do and make it affordable to homeowners.”

 

For suggestions on what to plant instead, read this 2013 update: Impatiens are dying; choose alternative shade plants instead

 

Have you experienced downy mildew on impatiens where you are?

Do you have more suggestions on what to plant instead of impatiens?

Please share your ideas below!

 

Photos by Margery Daughtrey

 

 UPDATE: See predictions for how well impatiens might fare during the summer of 2014 in Western New York.

Tags: , , , ,

82 Responses to Disease that’s killing impatiens may return for years; no treatment exists

  1. Catherine Hopewell on July 24, 2013 at 7:02 pm

    I live in Etobicoke, Ontario and usualy grow impatiens from seed purchased from Stokes in Niagara. I grew 2000 plants this year and find that they are gradually dying (July 24, 2013). The plants that were grown in the flower beds have died first but the plants grown in pots and tubs have lasted longer. This may suggest that the virus travels in air currents close to the ground or the soil I used for tubs and pots was less susceptible to harbouring the virus.
    The soil I used was a mixture of peat and a cubic yard of soil mixure bought at Canada Blooms in March 2013

    Next year I will order some different seeds as my effort this year has resulted in some sad-looking flower beds.

  2. Julie Ann Leigh-Lockett on July 24, 2013 at 9:57 pm

    My impatiens are still growing. I planted an experimental patch in the sun at the front of the house. After planting I sprayed them with fungicide. This seems to be working so far.
    I will let you know as soon as I see any deterioration in the plants.
    Julie
    July24 2013

  3. Connie on July 25, 2013 at 6:51 am

    Catherine, 2,000 impatiens plants! I feel so bad for you. From previous comments, it sounds as if pots located in sheltered spots may take longer to be affected. It would be nice if using a certain soil could slow down or stop downy mildew, but the experts don’t think that’s the case. Let us know what you decide to plant next year.

  4. Connie on July 25, 2013 at 6:54 am

    Julie, please keep us posted on your experiment with impatiens. Margery Daughtrey from Cornell said fungicide probably won’t work. Did you plant a control group that didn’t get sprayed with fungicide?

  5. Julie Ann lockett on August 8, 2013 at 10:18 pm

    The impatiens are still doing great and are quite a show at the front of the house. i Have noticed that there are not as many mildew type diseases around this year so far. The tomatoes have very little blight and the Phlox which are just coming out have much less than usual. . Over my experience the occurrence of downy mildews and other rusts and bunts are offer the result of very dry spells followed by rain. This is because the fungi attack an immune compromised plant which is flaccid. The cells are easy to penetrate and vulnerable. This year we have had lots of rain. It is an interesting year in my garden to say the least.

  6. Connie on August 9, 2013 at 8:17 am

    I’ve been hearing from gardeners who planted impatiens that they are still going strong. I hope they are still doing well in a couple weeks. I’ll keep my fingers crossed. Thanks for the update.

  7. Margery Daughtrey on August 11, 2013 at 7:49 am

    I saw a photo last week of an impatiens in the Buffalo area with the distinctive white sporulation on the under-surface of the leaves…. Definitely down mildew. Have any of the rest of you seen the disease yet this year? I am especially interested to hear if and when the disease reappears in a flower bed that showed the disease last year!

  8. kim on August 11, 2013 at 5:49 pm

    We plant 30 hanging baskets with impatiens and vinca vines. The vines are all fine, the impatiens have all died for the second year. We replaced all the soil this year, not knowing about this mildew. We have to plant in baskets because the deer eat everything. We live in the Poconos in PA. Does anyone know if this could spread to other plants, namely our vegetable garden?

  9. Connie on August 11, 2013 at 7:28 pm

    Kim,
    Margery Daughtrey from Cornell says that downy mildew affects only Impatiens walleriana (and the closely related balsam impatiens). Other plants, including vegetables, aren’t affected.

    Much information was shared in earlier comments. At the end of the article, just before the start of the comments, click on “Older Comments.”

    Good luck with your garden.

  10. Connie on August 16, 2013 at 12:34 pm

    On a new article, we’ve asked people to let Margery Daughtrey know how their impatiens are doing in 2013. As of Aug. 16, most people aren’t having many problems with downy mildew. See the comments here: http://www.buffalo-niagaragardening.com/2013/08/13/how-are-your-impatiens-doing-please-let-cornell-expert-know/

  11. Joan Kirkpartick on August 17, 2013 at 2:14 pm

    Hi! I live in the Bay Area in California. I have about a dozen large pots in my backyard, started them all with fresh soil and watered and fertilized since April 2013. Much to my sadness, I will be pulling out three pots and some also that I planted in the ground, The rest don’t seem to be too affected, but also are not delivering the volume of flowers as in the past. I will probably experiment with other plants, but can you tell me if I need to empty all soil? Also, I heard that you shouldn’t put the soil in the yard waste bin! is this true? i usually do so every two years and scrub, wash the pot with a bleach/water solution. Impatiens are one of my very favorite plants and I am not alone. Sorry to hear about this, but glad it wasn’t a result of my care! Thank you!

  12. Margery Daughtrey on August 17, 2013 at 4:03 pm

    Joan, if I were you I would just switch to growing a different plant, and not worry about the soil itself. It is kind to your neighbors to pull out impatiens plants that show a white coating of downy mildew on the undersides of the leaves (they will die anyway once they are infected, and before that the spores will keep blowing around the neighborhood until you bag them up. Leaving the soil there is no threat to your neighbors’ plants or any other kind of plant other than an impatiens: you can plant New Guinea impatiens in the same containers or ground bed, or tomatoes or vinca or whatever you want. You only need to remove the soil if you want to try impatiens again, and growing impatiens would be a risky proposition even if you did remove the soil and scrub the containers, since it can blow in on the wind.
    Cheers,
    Margery

  13. Judy on August 22, 2013 at 10:00 pm

    I’m so sad that the impatiens are being affected by this disease. They are my favorite summer flower for the north side of our home & shade area of our yard. It’s interesting that all the potted impatiens close to the house are dying but the plants about 20-30 ft from the house are flourishing. Maybe because they get some morning sun? At first I thought the spiders had something to do with it because they are busy critters this year.
    There is a home in our village that always has the most beautiful impatiens. As I drove by yesterday, I saw they are surviving and are absolutely stunning. I’m happy for them that they are so beautiful.

  14. Wilma on September 1, 2013 at 12:47 pm

    I have be growing hundreds of impatiens for decades as I have a yard with a lot of shade. Up until this years they have always been lush and beautiful, whether they were in solid beds or in my window boxes or baskets. I live in Saskatoon Canada, and for the last few years we have had a lot of rain in June, with little sun and very cool nights. When I planted the bedding plants out the beginning of June as I usually do, they looked fine for several weeks although they did not grow much because of the dull wet weather. Then in July one by one they started to yellow followed by the stems losing all flowers and leaves. I started pulling out these plants and by the middle of July whole beds were empty. At this point all the plants in pots, and baskets were still fine and blooming well. The weather was now normal dry and warm. In Aug. I noticed some of the large pots stopped blooming and now had curling leaves that were turning grey with mold. Soon all in the pots and hanging baskets were dying. Now Sept. !st when i usually have mounds of color, all I have is dying plants. Today the north large planter is starting to show the first sign of curling impatiens leaves. This planter is under large eaves of the house so never has any rain or dew fall on it, so I guess that is why it is last. What I find very strange, is that most of these planters and pots also contain tuberous begonias, which oddly enough have NO downy mildew this year. I have no idea what I will now plant in all my shade areas next year. Very upsetting !

  15. Connie on September 1, 2013 at 2:27 pm

    Wilma, I’m sorry to hear about your impatiens. That is a sad story. Here is an article with suggestions on what you might plant instead of impatiens. People in the Buffalo area seem to be going with begonias and coleus.

  16. Wilma on September 1, 2013 at 6:47 pm

    While I would not mind planting begonias [tuberous] instead, they are way too expensive to cover large areas. Besides at ground level they too usually develop mildew when you have rain and cool nights. As for the coleus, I have tried them with very limited success. They do not like the cool nights we get, even if the days are hot. The only thing I can think of is the small flowered fibrous begonias, I already grow a large bed of. However I find they do like a little more light, to do well, so many of the full shade areas will be a real problem. I currently have a large area devoted to hosta, so I really think, any more would be boring. Now if I could just convince the neighbors on both sides to cut down some of their 60-80 ft evergreens, I would have the light I used to have when I moved to this property more than 35 years ago. I do not have any large trees in my yard!

  17. Carol Kaczynski on September 1, 2013 at 7:41 pm

    I grew Dragon Wing begonias this year in place of impatiens. Although more expensive, they can be spaced 18 inches apart and mine are now 16-18 inches tall. They flower continually and make quite an impact. I have them in brick planters, one of which is under a porch roof. The lower light under the roof hasn’t slowed them down at all. Six Dragon Wings are covering the same or more area than 18 impatiens or fibrous begonias.

  18. Connie on September 1, 2013 at 9:55 pm

    Carol, I’m glad dragon wing begonias are doing so well for you. Thanks for the tip.

  19. Kristine on September 4, 2013 at 7:56 pm

    Here in Mt. Prospect, Illinois (northwest suburbs of Chicago) things were going fine with the impatiens, until early August.

    Due to the dire warnings, I only planted a few this year, and kept them all to pots (the greenhouse-men advised me that potted plants wouldn’t be susceptible. They were wrong.)

    They started out spectacular, but now all the plants are now failing, except for a few “Victoria Rose” that get strong afternoon sun. I’m not sure what to replace them with next year — I already use all the recommended substitutions, and none of them will quite fill the bill. It’s a sad day.

  20. Penny on September 5, 2013 at 4:08 am

    This year I used only orange/red impatiens in pots, and they were all beautiful until the first week of September. I didn’t see any curling leaves, no mildew, and there were lots of flowers. Then I noticed one wilting stem. I thought it had broken off, but when I took it off it was mushy, and when I touched the main stem it was mushy too, and broke off at the soil line. The plant still looked great, but probably would have soon collapsed. These symptoms sound different from the mildew blight that is causing the national problem. The description of Botridis (sorry, can’t remember the spelling) sounds closer, but I’ve been growing impatiens for many years and have never seen the dissolving stems before. It’s a lot like frost damage. It’s been very dry here (Boston area) for weeks until the last few days, when we had one fairly heavy rainstorm.

    I, too, have shade from a neighbor’s tall hemlocks. It would be nice if people would be more considerate . . .

  21. Connie on September 5, 2013 at 6:53 am

    Margery, please note that Penny lives in the Boston, NY area, not Massachusetts.

  22. DIETER SCHRAMM on September 8, 2013 at 1:31 pm

    Last summer all of our impatiens died of this disease. However this year all of the plants that we raised from seed are doing just fine. Westchester County, NY. September 8.2013

  23. Penny on September 8, 2013 at 2:15 pm

    No, not NY. My home (and plants!)are near Boston,in Massachusetts.

  24. Connie on September 9, 2013 at 7:34 am

    Penny, I’m so sorry. I had you confused with a different Penny. Now I see that your emails are different. Thanks so much for the correction!

  25. Roebstuart on August 6, 2014 at 9:47 am

    Hello

    I planted inpatient plants for the first time. They were doing so good but after a week of rain I noticed white spots on the flowers and they are beginning to die and all the new flowers that are not open yet are dead. I picked all the dead flowers off and start to spray them with a fungi spray that kills up to 80 diseases. I just sprayed them on Monday. I thought it might be that Downy Mildew but I notice that you all say the leaves turn white. My leaves are nice and green it’s only the flowers that have the white spots. It doesn’t look like powder mildew either. Does anybody know what this could be. My neighbor just put a bunch of mulch down on his driveway….could that have done it? Thanks

  26. Connie on August 6, 2014 at 10:33 am

    I’m sorry to hear about the problem with your flowers. First, I would suggest you check out the update on impatiens for Western New York I did on May 6, 2014. It’s a long article, and toward the end there’s a section headed “Tips for getting impatiens to perform well in your garden.” In that section, you’ll see a link to photos of the symptoms of downy mildew. That has more photos and shows a range of symptoms. The symptoms may subtle and not be as apparent as they appear in the photo in this article from 2012. The leaves can be green on top and still be affected. You may have to look very closely at the leaves of your plant to spot downy mildew. If you still think it’s not downy mildew, contact the Master Gardeners at Cornell Cooperative Extension in your county. I hope that helps.

  27. Roebstuart on August 6, 2014 at 11:50 am

    Thank you Connie for your response I will for sure check out those articles. I will also post how the plants are doing in about a week. It wonder if the Spray is going to help. I have to spray them next Sunday again. I would hate for them to die right at the very end of the summer season. Everyone in our development enjoys them so much being the first home you see as you enter the complex. Thanks again

  28. Connie on August 6, 2014 at 12:25 pm

    If you have downy mildew, none of those sprays will work. Also, last year some people who planted impatiens said the flowers were great, until the end of July or beginning of August. See the comments at the end of the 2013 article “How are your impatiens doing? Please let Cornell expert know.” Having a couple good months, then losing impatiens well before the first frost, may be what we can expect now in Western New York. It’s hard to say.

  29. Roebstuart on August 7, 2014 at 10:44 am

    Hi Connie

    Update on my inpatient flowers well I used the Daconil Fungicide concentrate and I bought a spray bottle. After many reviews these per made spray bottles don’t spray well so I decided to do it myself. This was on Sunday before I spoke to you. Today I went out there to pluck the dead flowers out and all the new flowers have opened up and none of them have the white spots. So maybe it was now Downy Mildew. This Daconil prevents over 80 Diseases. I’m so glad I tried it. It work really good for anyone who needs to buy a spray. Thank you for the advise but I’m also glad I took the chance of spraying them just incase it was not Downey. roeb

  30. Connie on August 7, 2014 at 10:57 am

    Roeb, I’m glad to hear of your success. I mentioned that you can contact the Cornell Cooperative Extension Master Gardeners if you don’t know what problem is affecting your plants. The other thing you can do it cut off a piece of the affected plant, pop it into a clear plastic bag and take it with you to your local garden center– one that has trained staff. They will help you identify the disease and the best treatment for it. A person from Lockwood’s Greenhouses told me of a customer who wanted to know what to spray to take care of the things on a plant. It turned out what she had was ladybug larvae– those are a tremendous help to a garden and shouldn’t be killed at all! I’m glad you were able to find a solution.

  31. Margery Daughtrey on August 7, 2014 at 10:59 am

    Roeb, I don’t think you had downy mildew on your impatiens. Once an impatiens has downy mildew the plant quits flowering, defoliates, and dies—and fungicides cannot stop the collapse of the plant. Fungicides that greenhouse growers have access to are able to PROTECT impatiens against downy mildew, but not CURE them… There aren’t any effective materials for home gardeners to use against downy mildew, alas. The infection is systemic, throughout the interior of the plant, so there is no way to reach into the plant to halt the disease. I’m glad your plants are looking better again. Those of you in the Buffalo area may find that you see downy mildew on impatiens in the near future, however….we have gotten some samples of the disease from Buffalo on both balsams (I. balsamina) and bedding plant impatiens (I. walleriana)—just in the past week. Drier weather will mean fewer outbreaks—this disease takes advantage of those summer thunderstorms like the one I got caught in in Ithaca day before yesterday.

  32. Connie on August 7, 2014 at 2:04 pm

    Margery, we’ve had rain often this summer. It’s nice for me because I don’t have to water my garden often, but it’s not great for folks who love impatiens. Thanks for for your comments.

Leave a Reply

Your email address will not be published. Required fields are marked *