Thursday, March 21, 2013

Impatiens on the critical list


An incurable disease is wiping out the common impatiens

A few years ago when I was in England for a press day at David Austin English Roses, I met a delightful woman who owned her own film company.

We became friends and before long she asked me to work with her and write a couple of videos for the Thompson & Morgan seed company.

The point of the videos was to introduce the firm’s new offerings for the upcoming season. One of the biggest stars of the T&M show was the Busy Lizzie, or as we call the plant, impatiens.

There were Busy Lizzies for borders, flower pouches, patio pots and hanging baskets.

Today Thompson & Morgan no longer sell the plants.

They don’t even sell the seeds.

That's because a deadly strain of downy mildew known as Plasmopara obducens is destroying plants around the world. 

A pathogen first discovered in the 1800's

The disastrous disease hit Europe about five years ago. Since then, impatiens have virtually disappeared from gardens there. Asia, Australia, Africa and Central America have suffered the same fate.

 In just two growing seasons here in America, the fungal mildew has spread to 34 states. Under the right conditions, airborne spores have been known to travel over 600 miles in 48 hours.

When infected leaves and stems fall on the ground, the spores take up residence in the soil. No one knows for sure how long the spores will live there – possibly as long as eight years.

SunPatiens Compact Blush Pink
I can attest to quick spread of disease. 

I had some “volunteers” come up in the front garden from impatiens I planted in 2011. I also put in two flats of white impatiens down by the new patio and waterfall.

By August the leaves started falling and within two weeks they all turned to mush.

As a result of the widespread nature of this incurable disease, many experts are advising gardeners not to purchase and plant impatiens this year. Fortunately, only the common variety (Impatiens walleriana) is affected by the pathogen.

SunPatiens and New Guinea Impatiens are in the clear. Apparently the disease does not sicken other garden plants either, so shade lovers like coleus, caladiums, hostas and begonias can help add color in areas where impatiens previously were the summer show-offs.

SunPatiens Vigorous Lavender
I am intrigued by photos I’ve seen of SunPatiens. They can be planted in full sun as well as shade and they grow much larger than the old favorite.

In fact Sakata Seed America, breeder of SunPatiens, reports four plants will provide the same coverage as twelve Impatiens walleriana.

 In addition, they are self cleaning, don’t mind rain, high heat or humidity. And they bloom right through from spring till hard frost.

If you simply can’t live without your beloved old fashioned Busy Lizzies and are willing to risk Plasmopara obducens, you need to be diligent about garden sanitation.

Keep your tools super clean, making sure you wash away any soil. To be extra careful, disinfect tools with a solution of 10% Clorox and water.

Also schedule work in the impatiens bed as your last gardening chore of the day.

SunPatiens Spreading White
If the disease comes to call anyway, place infected plants in sealed bags and dispose of them as soon as possible.

As for me, I’ll give impatiens a miss this year. Except I’m going to try a few of the new SunPatiens.

Last year’s experience was too heartbreaking to go through again.


Anonymous said...

I rely on impatiens a lot in my shady back garden, so this is distressing news. I don't really like New Guinea impatiens, but I'll check out the sunpatiens.

Lynn Hunt said...

Hi gardeninacity! I don't really like the New Guinea ones either -- in my experience they don't produce as many flowers.The SunPatiens do look promising -- particularly because they seem to spread out. I imagine they cost more (actually haven't seen any for sale yet) but the potential flower power will be worth it.

HolleyGarden said...

I usually pick up some impatiens every year, mostly for containers, but I think I'll pass this year, too. However, those SunPatiens sound wonderful! I'll be sure to look for them.

Lynn Hunt said...

HolleyGarden, I'm going to be in Florida visiting my mother after Easter and will be looking at all the garden centers there for some SunPatiens. They do appear to be healthy and robust!

Sunil Patel said...

Hi Lynn, the Impatiens downy mildew disease was heavily reported on in gardening TV last year in the UK, with trials of resistant varieties and potential substitutes. It is hitting us hard and I don't think there is any thing available that can combat the disease. I did have them in hanging baskets a couple of years ago, they were glorious for one summer and that's been it since.

Lynn Hunt said...

Hi Sunil, because the global problem wasn't reported so much here people are quite surprised to learn about this deadly disease. Apparently it was in some US greenhouses back in 2006, then seemed to go away. In 2011 it started spreading in a few states -- now I think we are up to 44. I hope they can create some resistant varieties eventually. It is sad.

I hear you have more snow! Will winter ever go away?

Sharon Lovejoy said...

So happy you visited. I am now your newest follower. I fell in love with your blog when I read your header about still scratching the surface.

I have been outdoors for the past three hours, planting sunflowers, weeding, and fertilizing. I'm pooped, but happy.

All joys to you,


Lynn Hunt said...

Sharon, you have made my day. Thank you so much.

Luckily I was able to get to tend the roses yesterday. Today was so cold and nasty with snow on the way.

Take care!

Daricia said...

I'm so disappointed to hear this, Lynn. I love impatiens! I had a beautiful double growing in a container that just suddenly died...I wonder if this is why? I thought it was surprising because I was taking good care of it. I'll have to look at some of the Sunpatiens this year.

Lynn Hunt said...

Daricia, I'll bet that is what happened to your double. The spores could've blown into your container and of course, it may have been infected right from the start. Apparently many plants act like yours -- look great for a time, then keel over.

Let's compare notes this summer as to how the SunPatiens are doing!

Les said...

At the botanical garden we have switched almost entirely to Sunpatiens and New Guineas. It might be years, if ever, before we grow common impatiens again.

Lynn Hunt said...

It's a shame Les, but I'll be interested in how you like the SunPatiens. Thanks for stopping by!

HELENE said...

I have grown both SunPatiens and New Guinea in the past, I like them both, I have even bought them from Thompson and Morgan I think, as I regularly buy plants from them. Here in the UK this disease has been reported on the news, and as Sunil says, new resistant varieties are on the way, but it takes time to develop new plants so it might still be a few years until we can find them in the shops and nurseries.

Lynn Hunt said...

Happy Easter Helene! This disease has been pretty much under the radar here until last year. I hope you and Sunil will keep me posted on developments in the UK. I wonder how long it will take to develop the new varieties? I'm looking forward to trying the SunPatiens.

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