My Impatiens are dying. What's up with that!

Do your impatiens look like this?  Mine do.  The Cause, Downy mildew.


 

 From UMass Dept of Agriculture:

Downy mildew of Impatiens, Plasmopara obduscens, has been reported sporadically since 2004 but it wasn’t until 2011 that widespread outbreaks were observed in landscapes in Massachusetts. Symptoms on  Impatiens walleriana typically start with a few leaves that appear slightly chlorotic or stippled, and become completely yellow over time. Some varieties will have subtle gray markings on the upper leaf surface. A white, downy-like growth may be present on the underside of primarily yellow leaves, but can also be found on the underside of green leaves.

As the disease progresses, premature leaf drop results in bare, leafless stems. Although the airborne spores remain viable for just a short time, Plasmopara produces a second spore type (a resting spore known as an Oospore) within the affected plant tissues. These resting spores are released into the soil as the diseased material decomposes and are likely to survive for extended periods. Research has shown no evidence of seed-borne transmission. Young plants, seedling cotyledons, and immature plant tissues are most susceptible to infection; leaf symptoms are often first observed on the younger growth. Plants infected at an early stage of development may show marked reductions in growth and leaf expansion. All varieties and intraspecific hybrids of Impatiens walleriana are susceptible to impatiens downy mildew, including both vegetative- and seed-produced I. walleriana.  There are no significant differences in susceptibility among varieties.

A few species of wild impatiens are also hosts of this disease, but there are no other known hosts. New Guinea impatiens (Impatiens hawkerii) is highly tolerant to this downy mildew.

Mark's Note:  I have been planting impatiens for year in my backyard and have never lost any, that is until this year so if you too have this problem be sure to dispose of the infected plants quickly so that it does not spread to your neighbors or other plants.

Follow these instructions if you have Downy Mildew:

If downy mildew shows up, promptly bag and remove infected plants to reduce spread to neighboring plants.  Space plants to allow air movement between plants. This will help reduce humidity and leaf moisture. If beds were infected in 2011, consider choosing a different annual plant this year.

Good luck.  Mark...