Is there really a disease that is killing the #1 selling annual? Say it ain't so! Should we be afraid to plant Impatiens? Unfortunately the answer is YES!!
If you haven't already heard there is a fungal disease that can kill your favorite shady annual, impatiens.
Impatiens downy mildew is a destructive foliar disease of
Impatiens walleriana
(the ones we all love) that is capable of causing complete defoliation or plant collapse,
especially in landscape plantings under moist conditions and cool
nights.
While there have been sporadic reports of impatiens downy mildew in
U.S. greenhouses since 2004, it was not until the summer of 2011 that
regional outbreaks of this disease were seen for the first time in
landscape beds and container plantings in North America. In early January 2012, outbreaks of impatiens downy mildew were
observed in landscape beds and greenhouses in south Florida. It is
unclear whether this was a continuation of the 2011 outbreaks or a new
cycle of disease for 2012. The spread of this disease continued
throughout the spring, and by October 2012, impatiens downy mildew had
been confirmed in landscape beds and/or greenhouses in 32 states including my home state of Massachusetts.
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| Shady flower border planted with impatiens |
Don't Impatiens just add a nice touch of color to a shady garden. The picture to the left is in my backyard and I for one love planting impatiens along the front border every season, well, except for this coming season. In 2012 I too lost all my impatiens to the "dreaded" downy mildew!
You can
click here and watch me and Todd from CBS Boston talk about it in my yard last summer.
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| Impatiens effected by downy mildew |
From what I have learned there is no guaranteed cure for the downy mildew. However if you do want to take your chances here are some tips.
1. Ask your local garden center if their impatiens have been treated with a fungicide. Growers are well aware of impatiens downy mildew and shown that fungicide rotations can be highly effective to prevent this disease while the plants are in production.
2. Inspect all impatiens that are purchased for planting, looking on the lower leaf surface for the
fuzzy sporulation.
3. Consider planting impatiens when air and soil temperatures are warm. If a region is experiencing
an extended cool, moist spring, it may be appropriate to delay planting for a few weeks. Impatiens
grow slowly under those conditions and will grow rapidly when planted later.
4. Set automatic sprinkler irrigation to run early in the morning, never in the evening or during the
night. Better yet, use drip irrigation to avoid getting water on the leaves.
5. Inspect planting beds. If small outbreaks of impatiens downy mildew are found, remove the
affected plants and neighboring plants immediately. Place the debris, including roots and fallen leaves, in plastic bags and close them to avoid spreading the spores. These plants should not be
composted. Make note of the planting areas, and avoid re-planting impatiens in these beds next
year.
6. If all else fails, plant something else! There are other great shady annuals to chose from and I for one will be experimenting with them all. Browalia, Begonias, Mimulus and Sunscape Impatiens.
I will blog next about Sunscape Impatiens. Looks like a nice replacement for
Impatiens walleriana For now. I wonder if it's a conspiracy?
If you have have of comments or questions please feel free to email me.
Mark Saidnawey
Pemberton Farms & Pemberton Garden Services
2225 Massachusetts Ave.
Cambridge, Ma 02140
617-447-0606
Mark@PembertonGardening.com