Impatiens - Downy Mildew

[GigaBuist]

I'm just tossing this out there.  I know most of us only grow stuff we can eat, but a few people might find this interesting.

I'll just start with that if you get Downy Mildew on your impatiens they're done.  They will lose all their leaves, will not flower, and they're basically dead.

During the winter of 2011 we were warned by the local university's extensions unit that works with agriculture that Downy Mildew of Impatiens had been spotted in Michigan.  Their concern was that we keep an eye out for it and toss out anything that looked to be contaminated.

Come spring this year we never saw anything, nor did any growers we work with, and we had very few complaints until recently.  Basically once the intense heat broke in this area dew began setting regularly and that made for perfect conditions for the fungus to come up.

We get about 1 call per hour about impatiens just dyeing off now.

Word is this is now a problem in 20 states.  I don't have the list in front of me.  I was originally just a problem in Florida, southern California, and one region of Pennsylvania.  But now it broke loose.  It's nuts.

The spores will remain dormant in soil for years, so if you get it you're basically screwed on ever planting impatiens again.  The other problem is that it spreads "for miles" according to the universities so if anybody around you had the problem you will too.  Nobody really knows how far this one spreads but it's closest relative affects cucumbers and that particular spore has been documented to spread 600 miles in 48 hours.

[zxcvbob]

Is that the same powdery mildew that gets on tall phlox and on monarda?  That stuff is ubiquitous already. 

[Perd Hapley]

Why are you guys in such a hurry?

[Jamie B]

Another gift from our international trading partners........

[MrsSmith]

I never cared much for impatiens anyway. Those and Stella D'Oro lilies are standard yard decor around here, and they have all the personality of a box of rocks. In fact, I'd rather just have rocks.
But I'm sorry your business is being affected negatively by this. Maybe a good time to introduce a new standard and get people excited by something different for a change.

[GigaBuist]

Is that the same powdery mildew that gets on tall phlox and on monarda?  That stuff is ubiquitous already. 

Nope.  Powdery mildew and downy mildew are different.

[Tallpine]

Tell them to stop using fabric softener in the hospital 

[zxcvbob]

Nope.  Powdery mildew and downy mildew are different.

I figured that out as I typed it; posted it anyway.   

Doesn't downy mildew respond to chlorothalonil?  Or how about quaternary ammonia (Consan Triple Action 20, or equivalent)?

[GigaBuist]

Another gift from our international trading partners........

It was first discovered in the US and that was back in 1942.

The bugger evolved.

Doesn't downy mildew respond to chlorothalonil?  Or how about quaternary ammonia (Consan Triple Action 20, or equivalent)?

I can't remember what should be used to keep it at bay, but basically all you can do is preventative treatments.  Once it's actually in a bed there's no solution.

Maybe a good time to introduce a new standard and get people excited by something differentfor a change.

Begonias and coleus are about the only other color you can get in shade around here, but coleus doesn't even flower.  Violas, which look a LOT like impatiens to me, can actually be done in the shade but they won't flower as much.

We'll figure something out.

[zxcvbob]

Check out "Polka-dot plant" (Hypoestes phyllostachya)

ETA: and don't forget about fancy-leaf caladiums

[Harold Tuttle]

Killing my dad's  d e a d  here in central pa.

Usually he has bushel basket sized plants by now.

The leaves fall off and you have green stems that wilt off.

I substituted wishbones and they are doing great.

[Harold Tuttle]

[zxcvbob]

What is that Harold, torenia?

[Harold Tuttle]

Yep, the deer are leaving mine alone and it's been blooming all summer.

[MrsSmith]

AND it's a pretty color!

[Harold Tuttle]

I have purples and pinks

[Scout26]

That is one of the most amazing pictures I have ever seen on a computer.  It's almost (heck it even might be) 3D.

[GigaBuist]

I had forgotten about torenia and polka-dot plants.  Both are things we carry but they're such minor players that they're quickly forgotten about.

Impatiens are between 30-40% of our bedding plant sales.  If you put torenia and polka-dot plants together I'd wager they're 5%.  Good suggestions though.

Caladium is right out, however, because that's a bulb item.  Can't really offer that in anything smaller than a 5" pot.

[280plus]

Couple things are happening here at my place. Cucumber big green leaves have all withered but they are still running shoots and producing. My best guess is too much water / root rot because the area they're in stays wet for days after it rains. I haven't watered all summer. Also the yellow squash have developed powdery mildew which I understand you can just wash off. They are still producing. Plus, we THINK we had the blight a few years back but it may have simply been the same too wet area plus swmbo watering religiously.

My question is is there anything I can treat the bed with this fall to limit any of this next year? I'm assuming I need to put the cukes elsewhere and concentrate on plants (vegetable or fruit) that like a lot of water. Also, I was going to turn the leftovers under at the end of the year but I read you're not supposed to do that if there is mildew etc present. I also read it doesn't matter because it's already there. Any thoughts on any of this are welcome.

[280plus]

In regards to the OP. What are the chances of you creating an isolated mildew free area indoors and trucking in uncontaminated soil? or,,, hydroponics?

[GigaBuist]

In regards to the OP. What are the chances of you creating an isolated mildew free area indoors and trucking in uncontaminated soil? or,,, hydroponics?

Everybody that grows impatiens in a greenhouse does them hydroponically.  Our "dirt" is a mix of various stuff, mostly sphagnum peat moss, and it's all sterile.

Selling stuff out of a sterile environment isn't the problem.  We can do that.  Problem is once you put it into the "wild" it'll get infected.

[GigaBuist]

My question is is there anything I can treat the bed with this fall to limit any of this next year? I'm assuming I need to put the cukes elsewhere and concentrate on plants (vegetable or fruit) that like a lot of water. Also, I was going to turn the leftovers under at the end of the year but I read you're not supposed to do that if there is mildew etc present. I also read it doesn't matter because it's already there. Any thoughts on any of this are welcome.

Once you get powdery mildew in the soil you're kinda sunk.  It won't go away.  You can move the cukes but it'll probably show up again because they pretty much encourage the disease.  It's a constant battle.

Hitting it with a copper based fungicide is good for stuff you eat.  Beyond that I'd just say try and keep things dry and hope it doesn't pop up.  I've had good luck at home with that technique.

[280plus]

Thanks for the info! 

[Harold Tuttle]

Torenia is heat, drought and sun tolerant and has had blossums the entire summer

It's a winner!

[zxcvbob]

I just remembered another winner -- wax leaf begonias.  I grew them from seed one year; a tall hybrid variety that I can't find anymore called something like "Stella".  Very easy, but you have to start the dust-like seeds really early.