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I have successfully germinated 10 lettuce seeds from a tissue and transplanted them into a pot. They grew more and showed new leaves, but after some time I noticed that their stem from the base started to turn brown and become thinner.

I googled it and I confirmed that my lettuce seedlings experienced what they called damping off. I read about how to prevent it and many said that the soil must be baked in an oven or sprayed with some anti-fungal, but that's not advisable because it may be toxic to plants and to people. The problem is that we don't have an oven to use and even if we have, my mother will not allow that method.

The next possible thing I can do is to let the soil dry from the sun but I don't if it's OK to do that, or are there other alternatives to prevent damping off from occurring again?

Sue Saddest Farewell TGO GL
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SilverRay
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  • I grow lettuce from seeds and have not encountered that problem. I plant the seeds directly in the soil. Any particular reason you are germinating the seeds from a tissue? – JStorage Jun 10 '16 at 01:14
  • I lived in the philippines and the lettuce do not usually grow in tropical countries. – SilverRay Jun 10 '16 at 01:18
  • It might be helpful if you tell us what exactly you're trying to do. Where are you planting the seeds after they germinate in the towel? What type of soil? Why not do it directly in the soil? The more details the better help you will get. – OrganicLawnDIY Jun 10 '16 at 01:36
  • You should be germinating in sterile seed raising mix. – Graham Chiu Jun 10 '16 at 06:18
  • Potting mix is the only available soil mix that the store have.... – SilverRay Jun 10 '16 at 07:45
  • Then use fine gravel, or vermiculite. After the seeds have germinated, you will need to add some liquid fertilisers when using soilless mixes. – Graham Chiu Jun 12 '16 at 22:31

2 Answers2

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There are a number of herbs and spices such as cinnamon, carnation, garlic, thyme and more that have shown effectiveness in preventing damping-off disease. You can see the results of a study here.

The extracts were more effective than just the spice powder but the spice powder had some effectiveness and is more readily available.

I've had some plants with issues with damping off in the past but none since I started using cinnamon.

Lettuce seeds are usually small and you tend to get a lot of them. You might have better success either sowing them directly where you plan to grow them or grow them in some potting mix and wait until they get bigger before you transplant them. Might be better off trying it that way instead of using a towel.

Sue Saddest Farewell TGO GL
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OrganicLawnDIY
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  • Did you use cinnamon extract or the powder is ok? How did you applied it in the soil? mix in water or mix in soil? – SilverRay Jun 10 '16 at 01:44
  • @SilverRay I use the powder. On bigger seeds I may sprinkle some on the seeds before sowing but most of the time just sprinkle on the surface. Once the plants start coming up outs important there's good air circulation too. – OrganicLawnDIY Jun 10 '16 at 02:17
  • This study indicates some (unspecified) phytotoxic effects for cinnamon on banana fruit in oil form at least. But it certainly doesn't seem to be worse than the fungus. http://www.fspublishers.org/published_papers/98263_..pdf –  Jun 10 '16 at 09:07
  • Thanks for the answer I tried it and it really works..... – SilverRay Jun 13 '16 at 00:44
  • @SilverRay glad I could help. How did you wind up doing it? Fix you use the towel method again? – OrganicLawnDIY Jun 13 '16 at 00:48
  • No, I just I followed your advice to sprinkle the cinnamon powder on the seedlings after they germinate and I don't see anymore browning or thinning of stems or other damping-off signs in my plants.... – SilverRay Jun 13 '16 at 03:38
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Using heat to eradicate soil-borne plant pathogens from nursery potting media ("soil sterilization") Oomycetes, including the fungi that cause damping off, can be killed by treating soil at 120°F (49°C).

Wayfaring Stranger
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