How to prevent damping off

A common problem

Preventing damping off is one of the biggest challenges most Chilli growers face. Damping off is a disease that manifests itself by seedlings toppling over in their trays.  Seedlings collapse because their roots and stems are infected by fungi and pathogens like rhizoctonia, fusarium, phytophthora and pythium. These fungi and pathogens cause the roots and base of the stems of seedlings to rot, which in turn leads to the death of the plant.

Once seedlings have damping off disease (which most likely was caused by pythium,) it will be too late. Unfortunately, they will die. What’s more – alarmingly so – once pythium makes its appearance, it can rapidly kill off many seedlings in quick succession. This is particularly so if the seedlings share the same source of water.

Luckily, damping off disease can be prevented. Various techniques can be used to reduce the likelihood of it developing. There are also various treatments that can be utilized to kill off the fungi and pathogens.  These treatments include Hydrogen Peroxide, seaweed extract and bio fungicides. The aim of these is to create a risk-free growing environment, where damping disease has little chance of success.

Biofungicides, in particular, are an exciting area to consider in combating dampening off disease. They are safe to use and effective.  However, there is a cost involved in using these products. If this is a factor in your Chilli growing, the following need to be considered first.


Inviting damping off

The conditions in which the fungi and pathogens thrive are cold, wet, undrained soil, high humidity and poor air circulation. These are conditions that can often be found in greenhouses and grow tents, but can also be present in seed beds outdoors.

Potting soil that is too wet, in particular, is inviting damping off disease to appear. To prevent potting soil from becoming too wet, it is best to ensure that it is prepared using a drainage medium like perlite.  Bottom watering is another way to ensure that potting soil  doesn’t become too engorged with water.. The aim should be keeping the soil just moist, without it becoming sodden

When growing in grow tents, it is important that air circulation is considered. Air circulation can be improved by using a mini fan. This is particularly important in grow tents, which get zipped up to retain heat.

If seeds are started in heated propagators, it is important to ensure the air vents are left open to prevent a buildup of condensation. When condensation is noticed on the lid of a propagator, it should be taken off and wiped off or allowed to dry before placing it back on.

Because the fungi that cause damping off disease thrive in cold soil, heating mats and grow lights should be used to keep the temperature of your potting mix warm. Doing this will not only make the conditions less conducive to damping off disease developing, but also make seedlings grow faster. This is important, because bigger plants are less likely to be infected by damping off disease.


Biofungicides and others

There are biofungicides that can be used to prevent damping off disease from developing. One contains Streptomyces ray bacteria isolated from Finnish Sphagnum.  Streptomyces are a bacteria that is effective in controlling damping-off, wilt and root diseases caused by Fusarium, Phytophthora, Alternaria and Pythium fungi. It also suppresses diseases caused by Rhizoctonia sp. and Botrytis sp.

Another treatment contains Trichoderma Harzianum. This is a fungus that is also used as a fungicide. It has been shown to be effective in controlling both seed and soil borne pathogens, causing damping off, root rot and wilt diseases.

Other treatments include diluted 3 % W/v hydrogen peroxide, seaweed extract and cinnamon powder. To make up the hydrogen peroxide treatment, simply add one tablespoon of three percent H202 to one quart of water (1.13 litres).

The seaweed extract should be diluted to 2ml per litre of water and applied by foliar spray. The extract does not act as an insecticide or fungicide. Instead, it strengthens the plants resistance to pests and diseases like aphids, red spider mites, powdery mildew, botrytis, and fungi responsible for the damping-off of seedlings.

Finally, the easiest and least expensive of the lot – cinnamon powder.  Cinnamon powder has anti fungal properties. By sprinkling it on top of your seed starting mix, it will prevent fungus from growing. It serves two purposes – the prevention of damping off, but it will also help keep fungus gnats away


These measures should work to prevent damping off happening, but there are more things you can do to prevent it. This includes only starting seeds with equipment thoroughly sanitised, by washing it warm soapy and chlorine bleach. Also use seed starting mixes that are sterile. I use worm castings for starting my seeds, as they are known to prevent damping off. It does this by camouflaging exudates

I am will shortly perform a trial with a biofungicide that contains Streptomyces bacteria.  I will be using it to start a new batch of seeds in the not too distant future. I expect great results from this product. It has had excellent reports that it is highly effective in preventing damping off.   I will let you know how it goes in an upcoming post.


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