No Impatiens This Year—Impatiens Downy Mildew

As I mentioned in an earlier e-mail, there is a disease hitting the common garden impatiens, Impatiens walleriana.  This is tough news for all gardeners because impatiens have been the #1 annual planted in gardens across the country for several years.  No other annual, in my opinion, lights up the shade with color like impatiens.

Downy mildew is a fungus.  The mildew spores, which can blow in the wind from miles away, or are found in soil and water, infect the leaves first.  Yellow spots appear on the tops of the leaves and white growths on the undersides of the leaves.  The plant goes downhill fast—wilting, then dying.  Spores can live in the soil for a year or more, surviving cold winter temperatures.  The fungus is fueled particularly by cool temperatures, high humidity, and rain or overhead sprinklers.

I have noticed this disease in my own garden, particularly last year.  I had no idea what caused it, thinking, at first, it might have been caused by spider mite or lack of water (even though the soil appeared wet).  Now I know.

We will not purchase or plant impatiens for our clients—or in our own gardens—this year, and perhaps for a few years to come.

At this time there is no cure or affordable chemical treatment.

By not planting for a few years, we may be able to break the cycle of the disease.  In a few years, resistant strains of the plant, or a chemical treatment, may become available.  It could be that impatiens may never be grown like they were in the past.

What are some good alternatives?  The New Guinea impatiens are not susceptible to downy mildew, but do require a bit more sun.  Begonias, caladiums, and coleus all come in many colorful varieties.  Another alternative is to use colorful tropical plants like gingers, pothos, etc.  Many of these have bright, colorful leaves and variegation.  Most tropical foliage plants will grow in some shade and love our hot, humid summers.  I use them every year in my own garden.

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