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| I have two dahlias in my dahlia garden that are showing signs of either disease or insect attack. Last year I lost my entire dahlia garden to disease, so I moved my tubers to a different location in a raised bed with drip irrigation. So far, they've been doing much better than last year, but now I see this. The link below leads to some photos of the problem. The first photo looks like disease to me, while the second photo looks a little more like insect attack, but I could easily be wrong. My question is, is there anything I can do to treat these dahlias, or should they be removed from the garden immediately so they don't infect other plants? |
Here is a link that might be useful: Photos of Ailing Dahlias
Follow-Up Postings:
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- Posted by misslucinda 6a (My Page) on Sat, Jul 12, 08 at 21:12
| Yikes, she doesn't look happy! I posted a thread almost identical to yours a few days ago and have been doing some research since. I hope this site works for you: |
Here is a link that might be useful: WSU.edu on dahlia diseases
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- Posted by sturgeonguy 5a Ont Canada (My Page) on Sat, Jul 12, 08 at 22:15
| Those are exactly the same effects mine are having due to spider mites. Eventually the entire leaf will go brown and dry as if its been unwatered. There's a very good article on spider mites on the American Dahlia Society's site: I couldn't manage the regiment described there. I have received a "Bug Blaster" from Lee Valley which I'm going to try. It is simply a high pressure spray attachment for your hose that gives off a 360 degree spray at right angles to the ground, so you can get under and over leaves. I have already tried spraying with Green Earth's Bio-Mist but it has had very little effect. The ADS article talks about simply pulling up affected plants and destroying them. I am hoping I can avoid that, but it is looking like it may very well be the most effective means of dealing with them. FWIW, I am also planning on increasing the water on my Dahlias since they aren't tubers (I don't have to worry as much about rotting tubers) and it may very well alter the spider mites cycles enough to throw them off. Good luck. Cheers, |
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- Posted by dahlia_newbie 9 (My Page) on Sun, Jul 13, 08 at 4:43
| I had the same thing destroy one of two miniature dahlias. ferocious little beasts. I'm seeing a small amount of damage on a few other plants in an entirely different bed too. I think I am going to try the bug blaster - thanks for the link. So disappointing-this is my first year with dahlias, and they have been looking so pretty until now (no blooms, but otherwise healthy and green). |
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- Posted by rose_nutty z4b (My Page) on Mon, Jul 14, 08 at 9:37
| It doesn't really look like spider mite damage to me, but I've been having more trouble with the little buggers than ever before in the history of my gardening. I've had several roses with heavy infestations. Controlling them is as simple as spraying the tops and bottoms of leaves on affected plants on a daily basis with a forceful spray of water from your hose. Just an ordinary nozzle with provide enough pressure to blow them off the plant. Just spray them very thoroughly - I do a couple of minutes on mine. Since this can in no way harm your plant, you can do it to them just in case it is spider mites. |
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- Posted by misslucinda 6a (My Page) on Mon, Jul 14, 08 at 10:23
| Excerpt from the Dahlia Society bulletin linked by Sturgeonguy: "Dahlia growers from 50 or 60 years ago would be astonished to hear our concerns with mites, because these tiny creatures were not a serious problem until after World War II. Interestingly, DDT created the mite problem two ways. First, DDT killed many mite predators. Moreover, DDT vastly increased the fertility of mites -- by greating increasing the number of eggs each female mite would lay and by substantially enhancing the percentage of mite eggs that hatched. A widely used miticide in the United States today is Sevin, a carbamate (same chemical class as DDT). I have always heard warnings not to use Seven on dahlias because it worsens mite problems. Dr. Ronald Ochoa's story about DDT explains why carbamates cause more problems than they cure for dahlia growers." An excellent and shocking article on how our use of one pesticide has had the unintended effect of being a fertility drug for at least one insect beastie if not many others...
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- Posted by raymondo17 z9 Sacramento (My Page) on Mon, Jul 14, 08 at 13:24
| Thank you all for your input. I'm inclined to agree that it is indeed spider mites, as there is webbing on some of the most damaged areas. Egad. One of my dahlias, a Mrs. Black, is pretty bad so I'll probably yank her. But one of my favorites, Midnight Moon, is also showing early signs. I'll give the water spray a try on this one. But won't spraying the little buggers off the dahlias just transport them to another area of the garden? -Ray |
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- Posted by sturgeonguy 5a ON (My Page) on Mon, Jul 14, 08 at 17:15
| Ray, According to the writings I've read, a good forceful water spray should actually kill them, not simply dislodge them. They're ultra-tiny soft-bodied insects...as you spray, keeping imagining the sounds of *MUSH* while you chant; "Take that you little beggers!"...;-] Cheers, |
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- Posted by raymondo17 z9 Sacramento (My Page) on Mon, Jul 14, 08 at 18:56
| LOL! Thanks for the chuckles, Russ. :) -Ray |
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