The nation's number one selling annual may not be offered by your local greenhouse this spring, thanks to a disease that's destroying the flowers from state to state.
Impatiens are well-loved by American gardeners because they happily bloom in full shade, flower all season and are generally remarkably easy to care for.
All that has changed, however, thanks to the introduction of impatiens downy mildew (Plasmopara obducens).
Impatiens downy mildew hit the U.S. hard in 2011 and in just two growing seasons it has already destroyed impatiens in 33 states -- and it's spreading fast.
Not only does the disease decimate impatiens, but it overwinters and destroys any healthy plants you bring in next year. Once impatiens downy mildew is in your soil, it can persist for at least a year and possibly several years.
Many gardeners thought their own impatiens died last year because of something in their own gardens, not realizing that the widespread disease was the culprit when the flowers withered and died.
The Sally Roth garden blog explains the symptoms:
First sign is paler green or yellow leaves, which often curl or look speckled or mottled. On their undersides is the whitish fungus, holding zillions of spores.
In just two weeks, all leaves drop and stems turn slimy and collapse.
The good news is that the disease is not a threat to other plants in your garden.
What can you do to combat impatiens downy mildew in your garden? Not much. The Winston-Salem Journal says:
Unfortunately, there is not a lot that a home gardener can do to combat the disease once it’s established. It is a fungus-like disease, but its activity is not easily arrested with fungicides. The best control for the home gardener is to remove plants that seem to be infected and to be fastidious about sanitation. Remember, plants and plant parts may contain spores with the ability to overwinter. Impatiens downy mildew is spread by spores that are easily transported through wind, rain splash and by the transport of infected plant material.
They go on to say:
The other strategy for defeating the disease, if it has become established, is to use change the plants you use in that bed next year. Instead of impatiens, try coleus, begonias or consider changing the bed from annuals to perennials. You may have to rely more on foliage color and texture rather than the color that impatiens provided.
Now greenhouses are facing two dilemmas. They first must find sources for healthy plants, and they have to figure out if they will sell impatiens to gardeners knowing that even healthy plants will probably catch the widespread disease and die.
Most "big box" garden centers such as Walmart and Lowe's will still carry impatiens. A sale is a sale to the retail giants. Local greenhouses are often choosing not to carry the annuals, however, not wanting to sell plants that are most likely going to fail and waste their customers' money.
Most garden retailers know that it's unscrupulous to continue to sell impatiens to American gardeners in current conditions. Horticulturist George Weigel explains:
Commercial greenhouses have chemicals that can keep a lid on the problem, but once out in the real world, airborne spores can quickly infect plants. Even if you try to spray, no fungicides that a homeowner can buy are very effective. Even then, you’d have to spray weekly. And that would get very expensive very quickly.
Meadows, Farms and Nurseries is one company that is not offering the flowers this year in any of their 23 mid-eastern locations, although they generally account for a quarter of the company's bedding plant sales. In a page on their website titled "Where are the impatiens?" they wrote:
Though you might find some retailers carrying impatiens, we feel it is our responsibility to suspend sales of impatiens indefinitely, and help our customers make informed choices for substitutions.
Company president Jay Meadows told the Baltimore Sun, "We hope other garden centers and nursery supply companies will refrain from the temptation to sell impatiens," he said. "We feel they are doing their customers an injustice by selling this product until this very serious disease is under control."
What can you plant instead of impatiens? Some acceptable shade-lovers include coleus, begonias, browallia, iresine, torenia, alternanthera, polka-dot plants (Hypoestes), sweet potato vines, caladium, and New Guinea impatiens (New Guinea impatiens are not affected by impatiens downy mildew).
Also consider using that shade to grow some edible plants. Low growing chocolate mint is a wonderful smelling filler in our family's shade gardens, for instance. See 40 Fruits, vegetables and herbs that will grow in partial shade for dozens of edibles that will grow in dappled shade.
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