Understanding Impatiens Downy Mildew: RETAILER FAQs.

Click here to view/download a PDF information sheet

Recognizing that a newly emerging disease of Impatiens may pose a threat to many businesses throughout the supply chain, the information below is compiled to help you understand more about this downy mildew disease. You’ll also find suggestions for alternative plants to help keep shade gardens in your community vibrant and colorful.

What is happening to impatiens?

Impatiens downy mildew is a disease that affects all varieties of Impatiens walleriana. This includes common bedding impatiens, double impatiens and hybrid impatiens. Infected plants drop their flowers and leaves, resulting in bare, leafless stems that eventually collapse. The telltale sign of this disease is a white, velvety covering on the leaf undersides.

Are any other bedding plants affected by Impatiens downy mildew?

While other bedding plants may be susceptible to downy mildew diseases, it is important for you and your customers to know that the downy mildew affecting impatiens only infects Impatiens walleriana and a few native species of wild impatiens.

Will Impatiens downy mildew survive from year to year?

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 I see plants infected with Impatiens downy mildew in my store, or if customers confirm it in their garden beds?

Promptly bag, seal and remove symptomatic plants from retail benches. If you spotted the white, velvety coating of spores on the leaf undersides, remove all bedding impatiens within three feet of the sporulating 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.

Where can I learn more about Impatiens downy mildew?

So…how do I satisfy customers shopping for shade plants?

Filling beds previously packed with impatiens could be a challenge and will no doubt require a wide assortment of plant material. Apart from baskets and patio pots, the majority of spaces your customers may be filling are quite large, so be sure to promote true alternatives for those customers looking for a suitable impatiens replacement.

Click here to check out some great shade alternatives



Early symptoms and warning signs of Impatiens downy mildew:

  • Light green yellowing or stippling of leaves
  • Downward curling of infected leaves
  • White velvety growth on the leaf UNDERSIDES


Advanced stages of Impatiens Downy Mildew:

  • Leaves and flowers drop, resulting in bare, leafless stems
  • Infected stems soften and plants may eventually collapse under wet and cool conditions

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