Help! dahlia wilt & rot with little bugs on tuber!!

mellylaxJune 27, 2006

Background: First timer here and new dahlia grower!!! I have 2 areas in my yard with dahlia's, both in full sun, but one on the southwest and the other on the south side of the house. I do have rather clayish soil, which I have amended with river loam (sandy stuff), peat moss & perlite several times over the last couple of years in prep for planting flowers and such. I planted bout 15 tubers in April, 12 of which sprouted nicely. Of the 12, only 1 has gotten to a respectable size - it is about 2.5' tall and is setting buds. All the others are under 8" in height. This week and while it was really hot, 6 wilted..2 from 1 area and 4 from the other.

I have been searching online for diseases & pests and and finally dug the poor things up tonight to get a look. I found really odd white lesions (not like mold, but more like tumors) on the stalks under the soil line and of course rotten tubers which were covered with hundreds..thousands.. millions..(not really) of the tiniest white bugs.. reminded me of termites and really grossed me out. I took some pictures and threw the tubers and and dirt with it in the garbage.. lots of the little bugs dropped off though..

I didn't find anything in the diseases that resembled this, and I didn't find any pests that looked like these things. So I don't know if my soil is too bad - or I watered too much - if the tubers started to rot and the bugs came, or if the bugs came and caused the rot? Have any of you encountered anything like this? I am so sad, I was so excited for them to bloom.

Also in the ground - using the same type soil and near the dahlias I have a lilac, honeysuckle, daphne odora, delphinium, lobelia, petunias, some hardy fushias & daffodils - all of which seem fine. Both the daphne and delphinium are very tempermental about wet soil and wilt prone, so I try to be really careful with my watering.

Thank you for your help!

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I'm here in Florida and I got the same thing, I was very disapointed, but I treated the Dahlias I had left by digging the rest of them up, spraying them with all things ant and roach killer only on the tubers let them sit over night rinsed them off and then treated the whole thing with a fungiside, I treated the entire area with all I had an ant and flea control for the outside the granule type. I replanted the other 7 and they are doing fine, these same little bugs I thought they kind of looked like mini locus myself also ate my Hostas in the same flower bed.
I don't know what the nasty little bug is but it ate up a big chunk of my yard allowance in plants. Now I am looking to buy or trade for other large hostas since there are none to be bought from retailers this time of year.

    Bookmark   June 30, 2006 at 4:09PM
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Thanks ptooming! I am sorry your dahlias and hostas are getting eaten and I really hope your treatment works! I just planted hostas for the first time too on the north side of the house.. of course 1 of them is looking puny so I hope it isn't this same stuff.

I did get to talk with my grandfather today - he was a professor in horticulture and plant pathology specializing fruits and berries. So I explained all I had seen. He said is likely that they are symphylans in the larval stage. The other thing they look like are "collembolans." They basically attack roots of plants and stunt growth and wilt things. So now I am going to try and dig up the rest and treat them. It sounds like they can be a problem here in my part of the world with our soils and they especially love it when you amend the soil, but he said the tubers may have been purchased already infected since I haven't had trouble before now.

It does sound like they are hard to get rid of once you have them, and can take up your whole yard, or just live in hot spots.. ie killing one set of plants and not the other. But the good news is they don't move well in the soil so maybe I can keep them from spreading?

Good luck and thanks!

    Bookmark   July 1, 2006 at 7:47PM
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Poochella(7 WA)

They are terrifying in appearance! Your grandfather sounds like a great resource. Did he say what to use to get rid of them, in case I ever meet one?

Here is a link that might be useful: Collembolans!

    Bookmark   July 1, 2006 at 11:48PM
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Well he said that diazanon works the best for killing the symphylans. Of couse it is off the market cos it is really bad stuff. We have actually ruled out collembolans, since they are mostly beneficial to soil and wouldn't cos the damage to the tubers. When collembolans do wreak havoc with plants it is apparently the greenery and above the soil line (symphylans hate light and keep underground.) I will have to ask him again about the current products that can be used - he rattled off a list of chemicals and fungicides and not necessarily brands of stuff.

I really hope that they never make it into anyones yards..
I attached a link to a helpful pdf that tells quite a bit about the symphylans and what they do - tests etc


Here is a link that might be useful: Symphylan Info PDF

    Bookmark   July 2, 2006 at 7:22PM
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Been a while since I have been able to get back here. So Sorry!! I am down loading that PFD as I am here to see if what we are talking about, could be the same thing. I don't know where they came from but it killed an enormous amount of tubers most of them before they could come up (discusted!!) I have treated the whole yard with Ortho MAX...I hate using pesticides since I have pets. I know I put in this Flower bed about March and it had all new purchased dirt in it, so I thought they might have come from either the tubers (dahlias &/or Hostas) or maybe even the new purchased dirt. ( An unwanted bonus...Yikes!! ) Then in the flower bed that has been established for some years prior to purchasing the house I put in Cyclamen about February, and they were doing wonderful I mean really great, set seed and everything, then 3 of the 4 went what I thought was 2 weeks ago I decided to plant other bulbs in there place, as soon as I dig them up they were sitting in these little creepy bugs, the tubers/bulbs were not damaged just the leaves, I washed them off gave them a good inspection sprayed them with a fungiside and replanted the little ones with a good dose of Ortho Max, The leaves are once again starting to come back up slowly but surely. This is why we decided to treat the entire yard...I put in a new flowerbed this weekend with Glads and young strawberry plants, I treated the bed before I put the mulch in, I have never had to put anything other than a bit of dish detergent on my Strawberries but I hope to ward off any creepy crawly root chewing scavengers before flowering season starts, once fowering season starts for my strawberries I won't use any pestisides in that flowerbed ( they better not like dish detergent ) It was a bit amusing though when I showed my husband a handful of dirt with the pesty creepy pests in it, all he said is he would be back in a bit, when he returned and he said with 2-20 pound bags of Ortho Max we will just treat the whole yard, those things are GROSS...Just to give you an idea of the over kill, I live in a Mobile home park my entire lot is 40X70!! He has since calmed down he said he would treat the yard that day ( he did )and then in another 10 days then we would do some digging in a few places to determine if we need to continue treatment or change treatments, but just to let you know my cheep Dahlia tubers that I purchased to replace the exspensive tubers, I planted last week are in fact coming up already and don't seem to be bothered by the Ortho Max or the bugs...the expensive tubers that did survive are not doing well even to this day and are always having to be treated with a fungiside, they weren't a good quality when I recieved them so I shouldn't be surprised. I hope you are doing well in the garden with your Dahlias, for me I am keeping my fingers crossed. Thanks for the information... I'll be back

    Bookmark   July 17, 2006 at 3:12PM
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