Urbana, Illinois, USA
June 17, 2014
Gardeners may continue to notice less and less garden impatiens (Impatiens walleriana) being sold in their local garden centers. This is due to a recent disease outbreak on impatiens called Downy Mildew of Impatiens (Plasmopara obducens), said a University of Illinois Extension horticulture educator.
“In 2011, the U of I Plant Clinic began receiving reports that downy mildew was a problem in landscapes in the Chicago area,” said Candice Miller. “The disease has continued to spread to other areas of Illinois at this point.
“This particular downy mildew affects all varieties of Impatiens walleriana, traditional garden impatiens. With downy mildew, gardeners will notice leaves curling downward on newer growth. Soon, white to light-gray fuzz may show on leaf undersides. New leaves may appear as stunted or discolored (yellow or pale green). Unfortunately, this disease can infect very quickly and cause complete leaf defoliation or plant collapse to occur,” she said
The U of I Plant Clinic recommends that gardeners who find downy mildew should remove all of the diseased plant material to avoid further infection in the garden or in neighbors' gardens. However, it may be difficult to rid the planting area of this disease because the pathogen can remain in the soil.
So what should a gardener do?
“This doesn’t mean gardeners can never plant impatiens again. But gardeners can look at this as an opportunity to diversify the garden and plant some alternative shade annuals,” Miller said.
Below is a list of great shade annual alternatives to try in your garden this year:
Begonias (Begonia sp.): Rex Begonia - Begonia rex-cultorum, Wax Begonia - Begonia x semperflorens, Tuberose Begonia - Begonia tuberhybrida, and Angel Wing Begonia - Begonia coccinea, are all great foliage or flowering plants for part-shade to shade.
Fuchsia (Fuchsia x hybrid): Nice blooms of reds, pinks, lavenders for the part shade. Great in hanging baskets.
Bloodleaf (Iresine herbstii): Shiny foliage plants with bright pink or lime green accents for part-shade to shade.
New Guinea Impatiens (Impatiens hawkeri): This species of impatiens is resistant to downy mildew. It features large flowers on vigorous plants in many colors for part-shade to shade.
Coleus (Solenostemon scutellariodes): Great, vigorous foliage plants for shade to part-shade with lots of colors and patterns. Some varieties available for sun as well.
Heliotrope (Heliotropium arborescens): Beautiful, fragrant, purple flowers best used in partial shade with moist, but not wet, soils.
Sweet potato vine (Ipomea batatas): Vining plant with various colors and shapes great for part shade.
Salvia (Salvia splendens): Various colored flowers best for partial shade.
Browallia (Browallia speciosa): Older reliable annual for abundant flowering. Best in partial shade.
“Check out the University of Illinois Extension website, Beyond Impatiens and Petunias at http://urbanext.illinois.edu/beyond/ for more information on shade alternatives,” Miller said.
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