Impatiens are being wiped out by a fungal disease called downy mildew. Impatiens downy mildew only affects varieties of Impatiens walleriana. This includes varieties of traditional impatiens, double impatiens, trailing impatiens and miniature impatiens.
Impatiens downy mildew has become prevalent in the Minneapolis-St. Paul Metro Area over the last three years. This fungal disease is present in the environment and spreads easily through movement in wind and water. Fungal spores will remain in the soil for a number of seasons after the initial infection. If you have had the disease in your garden, you will likely have it again.
Symptoms of the disease include yellowing of leaves accompanied by a downward cupping; giving the appearance that plants need to be watered. A fine white coating may be visible on the underside of the leaves. Over time, the flowers and leaves drop, leaving bare stems with a few small leaves left on top. Finally, the stems completely collapse and the plants die.
Once the plant is infected, it will not recover. Infected plants should be totally removed from the area (including all leaf debris and roots), bagged and disposed of immediately. Do not compost diseased plant material.
There are some cultural procedures that can help reduce the likely hood of infection:
- Buy plants from a reputable nursery.
- Space plants appropriately so that leaf surfaces will dry out quickly.
- Water more deeply and less often.
- Avoid watering in the evening.
- Avoid overhead irrigation.
- Plant impatiens later in the spring when extended periods of rain are less likely.
Tonkadale will carry a LIMITED number of Impatiens walleriana in 2014. Our impatiens are treated with a preventative fungicide which will provide protection for a number of weeks. Cost effective fungicides for homeowners are not available.
If you choose to plant impatiens in your containers or garden beds, Tonkadale is not responsible for any losses suffered and will not refund your purchase.
While nothing can replace an old garden standard that provides outstanding color and shade tolerance, there are many beautiful substitutions. 2014 is a year to try something new and make new friends!
- Shade Coleus
- Shade Lobelia
- New Guinea Impatiens (Impatiens hawkeri)
- Divine New Guinea Impatiens
- Wax Begonias
- Whopper Begonias
- Dragon Wing Begonias
- Shade foliage
- Perennial ground covers for shade
- A perennial shade garden
Good information is available on the University of Minnesota Extension website: www.extension.umn.edu