Downy mildew on impatiens becomes widespread in Michigan

February 3, 2013 – 02:05 pm

Downy mildew on impatiens

Landscapers should examine their plants for downy mildew and destroy infected plants.

Downy mildew on impatiens is a relatively new disease problem for greenhouse growers and now is being observed widely in Michigan landscapes. The downy mildew pathogen that infects bedding and double impatiens does not infect New Guinea impatiens, other flowering bedding plants or vegetables. Bedding impatiens are typically used in shady landscape areas and may be used in hanging pots. Double impatiens are typically used in hanging pots or other container plantings.

Infected impatiens may appear to be a bit off color with a white mildew coating the underside of the leaves. As the infection continues, the leaves may fall off of the plant, leaving only the stems behind.Downy mildew on impatiens en seed) that moves around the environment via air currents. When that spore settles out of the air and onto impatiens leaves, a new infection results.

A white mildew can be readily observed on the undersides of the
infected plants.

Another type of spore that is especially long-lasting may form in the stems of infected impatiens. These long-lasting spores are not readily visible without the aid of a microscope. If the impatiens plants with this long-lasting spore are not promptly removed from the garden and disposed of, the garden soil may become contaminated with the downy mildew pathogen.Downy mildew on impatiens essfully grow impatiens in the same location in another year.

A combination of symptoms may be observed, such as yellow
foliage and leaf dropping.

Professional landscapers have some fungicide choices available to them. These include Adorn (fluopicolide; apply as a spray or drench), Alude (phosphorous acid; apply as a spray or drench), Protect (mancozeb; apply as a spray) and Subdue MAXX (apply as a spray or drench). Greenhouse trials have indicated that Adorn, Alude and Subdue MAXX applications appear to be especially effective when applied as drenches prior to downy mildew infection.Downy mildew on impatiens a fungicide that can “cure” the plant.

Infected plants should be removed entirely from the landscape bed. No visible plant debris should be left behind in the landscape. All plant debris should be placed in a trash bag, closed and disposed of in the trash.

Dr. Hausbeck’s work is funded in part by MSU‘s AgBioResearch.

This article was published by Michigan State University Extension. For more information, visit . To contact an expert in your area, visit, or call 888-MSUE4MI (888-678-3464).


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Well sure. Florida. When I lived in Florida,

My yard always looked just right. It never looked a tangled, unplanned mess. Nature took care of all that. Okay, so I helped a little.
But you are kind.
'Colorpots' from Walmart, purchased at the end of the season, two years ago. Grown by a Florida nursery. Impatiens, geraniums, begonias, and other lovely flowers.
Survived the highs and lows of hurricane seasons, and the move north.
Placed in the unheated back room, with the door open. One night of severe cold, when the door was shut, all froze. Thought gone.
In the spring, the pots were placed outdoors, and nothing appeared to be recovering

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Home (Silks Are Forever)
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  • Height - 30
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Outsidepride Outsidepride Impatiens Baby Orange - 1000 Seeds
Lawn & Patio (Outsidepride)
  • Season: Annual
  • USDA Zones: 3 - 10
  • Height: 8 - 10 inches
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