powdery mildew

lila_newgardener(8)July 29, 2007

I don't know about the rest of you in the NW, but this last "pineapple express" has left quite a few of my dahlias with a ton of powdery mildew. I am new to dahlias so I don't really know how catastrophic this is... Will it go away with time, will it kill my infected plants? I sprayed some kinda stuff on them, but I didn't do too much because I don't like using chemicals, especially when I'm pregnant. Anyone have any advise for me?

Thanks :)

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First of all your Dahlias are very beautiful!!! I found some thing that may help you enormously (I hope). This is what I found going back to Nov 9th/05 on the message board......

Posted by raul_in_mexico 10 (My Page) on Wed, Nov 9, 05 at 14:27

I hate powdery mildew ! when the rainy season starts down here all that moisture is not good for my dahlias. But I use a simple remedy my granny taught me when mildew attacked her roses, baking soda, 2 teaspoons in a pint of water and a light spray and mildew dies in an eyeblink.

Please let us know if it works!

    Bookmark   July 30, 2007 at 2:10AM
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Thanks so much for reposting raul_in_mexico's post. I found it absolutely invaluable for my squash veggies.

Cheers to your granny for the recipe. I converted the recipe to 5Tbsp. baking soda/gallon water and it worked wonders on the heavy powdery mildew on my veggies. Sprayed every couple of days and within about 1week it was all gone. I sprayed my dahlias too as a preventative since they're next to veggie garden and no sign of any mildew.

I was concerned on the concentration of baking soda since most other recipes I've seen say a couple of "tsp" not "tbsp" per gallon. However, I haven't seen any toxic effect on the leaves of either veggies or dahlias. Recipe's a keeper!

    Bookmark   August 10, 2007 at 12:43PM
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donaldvancouver(cool wet z8)

Hi- I'm having the same trouble with my dahlias. I recommend a capful of neem oil in a litre/quart of water, with a few drops of dish soap to emulsify it. It's the best thing I've ever found against powdery mildew (not to mention scale and spider mites). Gives your plants a nice clean shine too.

    Bookmark   July 31, 2009 at 2:18PM
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Powdery mildew gets much worse as the weather cools down later in the year. I saw an organic gardeners dahlia patch that looked like field of snow white dahlias(leaves not flowers) on about August 10th one year.
Whatever you do, keep on top of it. Once a plant turns totally white on all leaves, it starts to die and the tubers do not store as well.
I have not sprayed my garden for insects in over ten years. But I have had to spray for powdery mildew each of the last 4 years.

    Bookmark   August 1, 2009 at 9:30PM
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The neem oil and dish soap trick worked wonderfully; my dahlias perked right back up!

    Bookmark   August 27, 2014 at 6:47AM
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