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MDA confirms downy mildew disease in impatiens

The Minnesota Department of Agriculture (MDA) has confirmed presence of impatiens downy mildew in the state again this year. Caused by a fungus, impatiens downy mildew damages leaves resulting in unmarketable plants.

The disease was discovered during MDA's new survey of foreign and emerging pests in nurseries. At this time, MDA is only surveying nurseries in the Twin Cities. Areas outside of the Twin Cities should take extra caution in looking for signs of impatiens downy mildew. Impatiens downy mildew was first found in Minnesota in 2011. It was also found in the state in 2012, but there were very few cases and no formal survey was conducted. Because cases of impatiens downy mildew have been found so early in the year, the potential for this disease to be wide-spread this year is significant.

Symptoms of impatiens downy mildew include:

· Leaves first appear light yellow or stippled yellow & green.

· Leaf edges curl downward; leaves appear wilted.

· Fluffy white growth occurs on the lower surface of leaves.

· Blossoms drop first. Next leaves fall off leaving bare green stems. Finally stems collapse and lay flat on the ground.

"It's unfortunate to find several cases of impatiens downy mildew so early in the growing season," said MDA Plant Protection Division Director Geir Friisoe. "This disease can spread quickly and can survive in soil for years, so it's important for consumers to know the signs and symptoms of impatiens downy mildew before the disease becomes too widespread to control."

Impatiens downy mildew can be spread through soil, plugs, and spores traveling in the wind and water. Varieties grown in gardens as well as in commercial greenhouses can be affected by this disease. There are preventative fungicides available, but there is no known treatment once an impatiens plant contracts downy mildew. Once an impatiens plant has downy mildew, it should be burned or buried to prevent further spread.

If you suspect you have basil downy mildew, please contact the Minnesota Department of Agriculture at or 1-888-545-6684 (voicemail).