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What happened to my Dahlias?

Posted by janinecollette 6 NJ ( on
Sat, Sep 29, 07 at 16:40

Hi All.. Need some of your expert advice :) I searched through my Ortho Problem Solver book, but I cant seem to figure out what happened to my beautiful dahlias (tears). Here's some pics of what they looked like a month ago. So full and healthy! Click the pic to see it larger.
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And here's what they look like now. They are lost all their bottom leaves which turned brown,I have been removing them, hence I guess why they look so thin. I'm sprayed them several times with the Ortho Systemic Insect Spray, but I guess it never helped. What do you think the problem was/is? I'm about to remove them bc they look so pitiful. :(
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Follow-Up Postings:

RE: What happened to my Dahlias?

  • Posted by knotz 8/PNW WA (My Page) on
    Sun, Sep 30, 07 at 12:19

Mine didn't do very well this year either...Powder mildew even though they are completely in the open...Most of mine look like yours...I don't know what caused this, but I think I'm going to get rid of mine and use the space for another type of flower.

I hope someone can help out...knotz

RE: What happened to my Dahlias?

Looks like powdery mildew to me (disclaimer: I'm no expert though). I used baking soda in water to spray on my heavily mildewed squash leaves this year (next to my dahlia bed which I sprayed too, just in case) and within days I saw recovery and my dahlias never got the mildew.
I used the recipe from previous forum post: 5 Tbsp. baking soda + 1 gallon water
The 5 Tbsp. sounded like a lot to me (thought it might be 5 tsp. instead) but I didn't see any detrimental effect on the squash or dahlias.


RE: What happened to my Dahlias?

Thanks All! Knotz, I think I am going to get rid of these after I dig them up as well. Never happened before.. Don't want a repeat next season :)

RE: What happened to my Dahlias?

It doesn't look like powdery mildew to me. Looks more like spider mites. In either case, it won't affect the tubers, so don't throw away (unless you're looking for a reason to get some new ones). But -- you should cut down the plants and get rid of the debris. DON'T COMPOST IT!!

I never compost any dahlia debris, just in case there is some disease or bug in it. I had dahlia smut this year for the first time, and I will be very careful to clean everything off the ground when I dig. Luckily I live in the country and can burn.


RE: What happened to my Dahlias?

That's what mine looked like too. I thought it was the heat. First timer with Dahlias here...only 2 plants. I cut them back...not even thinking they were coming back. They are now growing again. So I'm going to try to winter them.

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