Damping-off disease (early seedling death), DOD.

ianbrazil(11)April 8, 2013

This is one of the commonest forms of seedling loss, yet it is very hard to find a useful googleable access. If you find this article helpful please comment to keep it " in the headlines".

Damping-off disease is a general term to refer to a number of conditions that result in early seedling death. In a typical case seedlings will germinate then fail to thrive, eventually collapsing about a week after germination, though DOD can cause death as much as a month later. There are a variety of causes, both bacterial and fungal, which it is usually impossible to identify specifically. The only effective treatment is prevention as, once a seedling is already showing symptoms of DOD, it is usually too late.
The most effective treatment is complete sterilization of the growing compost before sowing. This can be effected in a number of ways but principally the temperature of the compost must be raised to close to 100C, 212F (boiling) for at least five minutes. The compost should be dampened before treatment. Small quantities of compost can be sterilized very effectively in a microwave oven. Chemical sterilization of compost is not very effective.It is not wise either to rely on commercially purchased compost being sterile.

After sowing keep the sowing area very well ventilated, if necessary use a fan. This will reduce the number of fungal spores ( which are present in any normal atmosphere) that settle on the compost. Water with a dilute solution of Bordeaux mixture (Copper Sulphate) for at least a month. Other commercial mixtures are available (though expensive) but do not rely on them without pre-sterilization. Small seeds are the most vulnerable.

Good luck - Ian.

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I ought to have added that, although commercially purchased seed should be sterile (in practise it often is not), seed saved from the garden never is. Since for the average gardener, fully sterilizing seed is not a practical option (dusting with sulfur will offer some protection), no method is completely foolproof. - Ian.

    Bookmark   April 8, 2013 at 11:51PM
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i didnt sterilize my soil before repoting my seedlings and i did that about 2 days ago. if my soil was bad how long would it take to see if my plants got the dod
and for the fan i can use one on seedlings?

This post was edited by John_JJ on Tue, Apr 9, 13 at 2:10

    Bookmark   April 9, 2013 at 2:05AM
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My guess is that if the plants were big enough to re-pot, they were old enough to not have a problem. If you want, aim a fan on them (you can use a timer so it only runs 1/2 or 1/3 of the time, periodically). A fan from 12 or 15 feet away is enough of a breeze to help. PS - a fan helps toughen up the stems so when you put them outside in the wind, they are sturdy and don't blow over. Two benefits!

Last night I re-potted 5 week old pepper plants and I'm not concerned about damping off. The stems seemed woody enough (not soft).

    Bookmark   April 9, 2013 at 7:22AM
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runswithscissors(MT 4/5)

Forgive me....bordeaux mixture? I have not heard of that, can you explain what it is?

    Bookmark   April 9, 2013 at 9:54PM
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please read the internet: Cornell University scientist Dr. Allison Jack has discovered that sterile medium bordeaux mixture, etc. IS ALL WRONG!!! The traditional organic method of earthworms and compost is powerful, cheap, and works best. Her research proves this.
To prevent damping off, I use a mix of 30% compost, 30% bark, and 40% peat based potting mix, called pro-mix.
You must have plenty of beneficial bacteria in the soil, and these are found in abundance in compost, expecially with worm casting enriched compost.
Last year, I attempted rose cuttings, and lost hundreds and hundreds of cuttings, because everything was sterile. Then I added compost, and the miracle of life happened. :) . I now use compost with all of my seedlings, and osmocote, because the seedling will never get damping off, and grow much stronger if it has a nutritious medium.

Here is a link that might be useful: How to prevent damping off, according to Cornell soil scientist Dr. Allison Jack

    Bookmark   April 10, 2013 at 11:26AM
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runswithscissors(MT 4/5)

Do you add worm castings or do you just rely on your own compost to have them? I have alot of worms in my yard, but honestly, they don't seem all that interested in my compost pile. (or perhaps I misread the scientific study).

    Bookmark   April 10, 2013 at 2:10PM
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runswithscissors(MT 4/5)

Overdrive - your post sparked my curiosity and I did some research into vermicomposting. I am amazed at how the humble earthworm might be the key to controling damping- off and other fungel diseases, not to mention adding super growing power to seedlings, at the stage they really need a kick-start. (at least in my operation.)

Thanks for bringing it to our attention. I'm going to start a worm bin for the future, but in the mean time I'm buying some worm castings to put in my germination mix for now. It makes perfect sence really...worms and plants did evolve together, didn't they?!

    Bookmark   April 10, 2013 at 2:54PM
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There was one study also done just using leaf compost without the worms, and the fresh leaf compost also worked well, they compared it to compost that had been stored for several years and the very old compost did not work as well. If you have access to worm castings, that is great, but worm castings are pretty expensive unless you have your own worms - my garden centre sells compost supposedly enriched with worm castings (who know how much or little), but I have been using both the compost from the local leaf composting company, and the store bought compost, and each one of these works well. I have also discovered that ground bark is very cheap, and is good to add to the mix, because it is both organic, and very porous, so the drainage is excellent and that helps to avoid a soggy soil, which as everyone knows is disaster - -

A farmer went out to sow his seed. 4 As he was scattering the seed, some fell along the path, and the birds came and ate it up. 5 Some fell on rocky places, where it did not have much soil. It sprang up quickly, because the soil was shallow. 6 But when the sun came up, the plants were scorched, and they withered because they had no root. 7 Other seed fell among thorns, which grew up and choked the plants. 8 Still other seed fell on good soil, where it produced a crop a hundred, sixty or thirty times what was sown.

Even in the times of the Bible everyone knew the seed needed good soil, but now we are told to use sterile mix with no nutrients - supposedly the seed already has a store of nutrients - which is true enough, but my own experiments with adding Osmocote to the potting mix, bonemeal, and compost, results in fantastic healthy seedlings - Is anyone surprised?

    Bookmark   April 10, 2013 at 10:22PM
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I have used jobes organic fertilizer when I transferred my seedlings to bigger cups. I also sterilized the mix (kill gnats mainly). They seem to be doing really well since the transfer, but it just might be the added space.

    Bookmark   April 11, 2013 at 12:07AM
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It is really sad to think of the millions of dollars of chemicals that have been poured into the environment, poisoning it, with antifungal agents, when organic methods work better and cheaper.

    Bookmark   April 11, 2013 at 8:56PM
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runswithscissors(MT 4/5)

Perhaps worm castings are becoming the "in" thing because I just bought a bag (19 Qts) of them for $12 at our local feed store. (Eko brand). Does that sound like an expensive price....a bag of miracle gro was $19.

    Bookmark   April 11, 2013 at 10:08PM
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naturemitch(3/4 WI)

Avoiding damping off is simple. Use a soilless mix, when seeds germinate....remove lids or plastics that have been used to keep in moisture, and put a fan on them. Also, learn not to overwater your seedlings.

I have been growing by seed for decades and have no issues with damping off. No teas used, certainly no sterilizing, just a good quality soilless mix.

Totally don't recommend adding compost to small containers of seedlings. Compost will mess with drainage, and more people loose seedlings to overwatering and poor drainage than you can imagine.

Not against organic, practice it myself, but put the compost on top of the mix when seedlings go into their large summer containers.

    Bookmark   April 12, 2013 at 1:16PM
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Air circulation is the key to preventing damping off. None of that other costly stuff matters.

If you do some research you'll see that worms aren't even very good for the garden. They eat the nutrients your plants need.

    Bookmark   April 12, 2013 at 5:11PM
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this is such an important topic it should stay as a permanent "sticky" at the top, for always - best regards, paul m.

    Bookmark   April 30, 2013 at 1:39PM
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Thanks for all you comments. Like any good gardener (I hope) I will always keep an open mind on most issues. At present I am running my own trial with a variety of seed, some commercial some collected from the garden, grown in 1. a sterile sand and garden soil mix grown in the open air and 2. a commercial vermiculite and peat-based mix without any additional sterilization but with plastic covers to prevent post-infection. OK don't tell me - it should be the other way round! I should also point out that any peat-based material is very environmentally incorrect as peat is a much over-exploited natural raw material and is actually banned from garden use in many countries, including mine!!! I'm not including non-sterile garden soil even with added sand as 20 years experience tells me it is no good.
I will now contradict everything I have said by saying that the best I results I get are from direct sowing!! This is evidence in favor of OVERDRIVE that non-sterile soil works best. If anyone can tell me why it works in the ground but not growing modules I'd love to know.
Will keep you all posted. - Ian.

    Bookmark   April 30, 2013 at 7:47PM
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The seedlings show no signs yet, in fact these sprouted in 3 days and jumped up fast. You can see the "fuzz" around the seed. I lightly raked in some cinnamon, and sprayed with Captan. Never had it before, and I can only think it was on the seeds. We'll see how they do...

    Bookmark   December 13, 2013 at 12:15AM
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another pick

    Bookmark   December 13, 2013 at 12:16AM
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Just seeing the odd seedling in my greenhouse falling over - given the seedings a good preventative spray with Bordeaux Mixture - hopefully ot will prevent further problems. Is it OK to store unused solutions?

    Bookmark   March 31, 2014 at 12:41PM
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ZachS. z5 Littleton, CO

So, I want to throw my own $.02 in here because I think there's a lot of factors to consider here.

Keep in mind the way some do it is not the only way. There are as many ways to grow plants as there are people who do it.

In regards to compost, worm castings, garden soil etc. used in a seed starting cell or tray I do not follow that practice or recommend it to other growers. The main reason is compaction and the other is sterility.

Because this is a thread on DOD we'll discuss the sterility. It is, to me, important to use a "clean" mix when starting seeds indoors rather then one that is rife with microbes. The reason is volume and concentration of those microbes as well as the environment.

You simply cannot compare an indoor seedling "nursery" to your outdoor garden. While all of the above ingredients a happy garden make, in the very different environment of a seed starting tray it has the potential to be very detrimental. The wet, warm soil, combined with low air movement and lack of temperature fluctuations all in a volume of soil that is many times smaller then an outdoor garden can cause an imbalance in the microflora of the soil.

In particular, I think, the overwatering is the largest detriment to seedlings for a myriad of reasons. Specifically for DOD, not only is a warm wet medium especially appealing to most microbes, the lack of air space in the soil in conducive mostly to anaerobic life forms which, generally speaking, pose more of a problem then aerobic ones.

I am not trying to spread doom and gloom, because there are lots and lots people who use straight compost and garden soil to start seeds indoors and have great success. I don't do it and I also have great success. This is simply my reasoning on why I chose to do things this way.

    Bookmark   March 31, 2014 at 3:33PM
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