Are you having trouble finding impatiens in garden centers this spring? Did the ones you planted last year struggle to grow or develop mildew?
The answer to both of these questions is that downy mildew infected the nation’s impatiens rootstock.
Numerous plugs and cuttings growers received last year were infected and those that weren’t soon were. This season, there is only a small stock of impatiens not infected, despite the best efforts of growers.
Downy mildew is a disease affecting annual impatiens (walleriana) and several wild impatiens species. Infected plants drop their leaves and flowers, leaving bare stems that collapse.
The first sign of infection is white webbing on plant leaves. According to a recent article in Bloomberg News, the fungus was first detected in the U.S. in 2004 and is now found in 33 states.
If you see this white webbing on impatiens leaves, act fast and yank the plant and those around it. Photo courtesty of Purdue University.
Other annuals are also susceptible to downy mildew diseases, but not the strain that hits impatiens. However, there is strong evidence that the impatiens downy mildew strain survives in the ground over winter and can affect newly-planted impatiens the next season.
If your impatiens is infected with downy mildew, pull it out of the ground or container immediately. Put it in the trash; DON’T compost infected impatiens. The fungi will live through the heat of composting.
Shade Plant Alternatives
New Guinea impatiens is not susceptible to downy mildew diseases (it’s a different species) and makes a great substitute. Also, consider fibrous begonias and lobelia, both fast-growing annuals for the shade with plenty of colorful flowers.
New Guinea impatiens is not affected by downy mildew disease. Photo courtesty of Proven Winners.
Multicolored leafy annuals like coleus and caladium offer instant color when planted, too, and they love the shade. You can also dig up caladium bulbs in the fall, store them in peat moss in a dark closet and replant the next season.
Consider a colorful leafed alternative to impatiens in the shade, like these coleus. Photo courtesy of Rutgers University.