What happened to Impatiens?

IMPATIENS PROBLEM /  DOWNEY MILDEW DISEASE

IMPATIENS WALLERIANA

In mid-summer of 2012 gardeners across New Jersey helplessly watched as our beloved impatiens, the colorful backbone of shade gardens, weakened, turned yellow, dropped their leaves, wilted and died.

By October it was confirmed that DOWNY MILDEW disease had been confirmed in our landscapes. From Massachusetts to Florida; New Jersey to Missouri and even Southern California impatiens failed. By the end of last year 32 states reported Downey Mildew.

This disease, known as a "water mold" (formerly called a fungus)  was quickly spread by  two types of spores.  One air borne with a short life span and the other, incased in water which can remain viable for years. Unfortunately these spores overwinter in garden bed soil . Many countries in Europe have not been unable to plant impatiens for many years.

IT IS NOT RECOMMENDED WE PLANT IMPATIENS AGAIN THIS YEAR.

A few garden centers and big chain stores plan to grow and sell impatiens this year. They were able in past years to control the disease with fungicides in greenhouses and plan to do so again.  This protection wears off quickly once moved into our gardens where the plants lack a controlled environment. Even potted plants are not safe from the air-born spores. The best we can hope for is a 30% success rate.  Sadly this collapse takes place at the peak of the season when there is no time to replace them.

 

The first sign of Downy mildew is a white film on the underside of the leaves. Within days total collapse of the plant will occur.  Immediately remove the plant. Put it in a sealed plastic bag and place it in the trash; not the compost bin.

 

Cooperative Extensions suggest folks find an alternative to plant in their garden. New Guinea impatiens and Sunpatiens  (Hybrid of regular & New Guinea) have a higher resistance to downy  mildew.

Coleus with colorful leaves

 

Begonias

or Caladium would be a few good choices. 

 

 

 

Beautiful new Hosta hybrids can add light to shaded areas that will last for years to come.

 

Although this is very disappointing to gardeners, this is a disaster to landscapers, greenhouses and seed companies.  Researchers across the country and the Department of Agriculture are working to solve this problem as quickly as possible.

When we planted impatiens we never thought we were part of a multi-million dollar industry, but we were.

Happy Gardening,
James