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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.

 

       Impatien Alternatives for the Shade

 

The following list of plant material offers substitutes for impatiens in 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 will refer to less than 3 hours of direct sunlight each day and filtered sun

                      the remaining hours of the day

   

 

           

 

Bedding Plant Annual Flats & 6" Pots - standard seed-grown varieties 

           

 

Full Shade

Part Shade

Part Shade

 

Coleus

 

Ageratum

Nicotiana

 

Dusty Miller

Alyssum

 

Petunia

 

 

Hypoestes

Begonias Wax

Salvia

 

 

   

Dahlia

 

Snapdragon

 

   

Dianthus

 

Verbena

 

 

   

Lobelia

     

 

           

 

4.5" & 8" Premium Annuals - vegetative-grown varieties 

 

           

 

Full Shade

   

Part Shade

 

Browallia

   

Alternanthera

 

Caladiums

   

Antirrhinum (Snapdragons)

 

Grass Fiber Optic

   

Begonia tuberous (non-stop, Rex)

 

New Guinea Impatiens

 

Ipomoea (Sweet Potato Vine)

 

SunPatiens (New Guinea)

 

Osteospermum

 

       

Perilla

 

 

       

Sun Coleus

 

       

Torenia

 

 

       

Vinca Vine

 

           

 

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

           

 

Full Shade

   

Part Shade

 

Aralia Sun King

   

Ajuga

 

 

Fern

     

Aquilegia

 

Heuchera & Heucherella

 

Astilbe

 

 

Hosta

     

Dicentra

 

 

Lysimachia

   

Heuchera & Heucherella

 

Polemonium

   

Oxalis

 

 

Polygonataum

   

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