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Home > Lawn & Garden Resources > Spring & Summer > The Latest on Impatiens

The Latest on Impatiens

Impatiens Downy Mildew

What is happening to impatiens?

Impatiens downy mildew is a disease that affects all varieties of Impatiens walleriana (standard seed, bedding plant impatiens).  This includes common bedding impatiens, double impatiens and hybrid impatiens.  This does not include New Guinea Impatiens.  Infected plants drop their flowers and leaves, resulting in bare, leafless stems that eventually collapse. The disease can be easily identified by white powdery spores on the undersides of the foliage.

Impatiens walleriana - All cultivars of Impatiens walleriana and hybrids (seed-raised impatiens and vegetative grown premium impatiens) are susceptible including Fusion, Fiesta, and Patchwork.

New Guinea Impatiens (Impatiens hawkeri) including Fanfare, Divine, Celebration, Celebrette and Sunpatiens have a very high resistance to impatiens downy mildew (IDM) and have shown no symptoms of this disease in the landscape.

Are other bedding plants affected by Impatiens Downy Mildew?

While other bedding plants may be susceptible to downy mildew diseases in general, it is important to realize that the downy mildew affecting impatiens only infects Impatiens walleriana and a few native species of wild impatiens.

Will this disease survive through the winter?

There is some evidence that the pathogen that causes Impatiens downy mildew may survive in garden beds from year to year, so impatiens planted into beds with a history of this disease may be at a higher risk for infection. However, impatiens may become infected by windblown spores even if planted into garden beds with no history of this disease.

What should I do if my Impatiens become infected with IDM?

If you spotted the powdery white spores on the undersides of the leaves, remove all bedding impatiens within three feet of the infected plants.  If observed in garden beds or outdoor containers, infected plants and any fallen leaf debris should be removed promptly, preferably well before the plants collapse. Discard bagged plants with regular waste. DO NOT COMPOST.

A bed of flowering impatiensclose up of a pink double impatien

Impatiens Alternatives for the Shade

The following list of plant material offers substitutes for impatiens for part shade to full shade locations.

Partial shade refers to locations that offer 3-6 hours of sun per day and preferably direct sun would be in the morning or early afternoon.

Full shade refers to less than 3 hours of direct sunlight each day and filtered sun the remaining hours of the day.

Bedding plant annuals & 6” pots-                                                 4.5” & 6/8” premium annuals-
standard seed-grown varieties                                                vegetative-grown varieties

Full Shade
     Coleus
     Dusty Miller
     Hypoestes (Polka Dot Plant)

Part Shade
     Ageratum
     Alyssum
     Begonias (wax leaf)
     Dahlia
     Dianthus
     Lobelia
     Nicotiana (Flowering Tobacco)
     Petunia
     Salvia
     Snapdragon
     Verbena
Full Shade
     Browallia
     Caladiums
     Fiber Optic Grass
     New Guinea Impatiens

Part Shade
     Alternathera (Joseph’s Coat)
     Antirrhinum (Snapdragons)
     Begonia (Tuberous/Nonstop)
     Ipomoea (Sweet Potato Vine)
     Osteopermum (African Daisy)
     Perilla (Shiso)
     Sun Coleus
     Torenia (Wishbone Flower)
     Vinca Vine

 

 

 

 

 

 

 

 

 

 

Perennial substitutes-
plants that die back to the ground and return each spring

Full Shade
     Aralia, Sun King
     Ferns
     Heuchera & Heucherella (Coral Bells)
     Hosta
     Lysimachia (Creeping Jenny)
     Polemonium (Jacob’s Ladder)
     Polygonatum (Solomon’s Seal)

Part Shade
     Ajuga (Bugleweed)
     Aquilegia (Columbine)
     Astilbe (False Spirea)
     Dicentra (Bleeding Heart)
     Heuchera & Heucherella (Coral Bells)
     Oxalis
     Viola

 

 

 

 

 

 

 

 

 

 

 

 

 

Helpful Links

Greenhouse Grower - Impatiens Downy Mildew Incidence Down Significantly in 2013

 

Greenhouse Grower - Impatiens Downy Mildew:  2013 And Beyond

 

American Floral Endowment - Controlling Downy Mildew on Impatiens Walleriana