Damping off is a disease or condition that occurs in horticultural plants. This condition damages or weakens the seedlings during the process of germination. It is caused by different pathogens and is mostly found in wet and cool conditions. Damping-off is caused by several seed-borne and soil-borne fungi including Rhizoctonia solani and Aphanomyces cochlioides. It is also caused by oomycetes and different fungal species which include Pythium, Fusarium, Phytophthora, Botrytis, Cylindrocladium, Diplodia, Phoma, and Alternaria. Damping off caused by these pathogens has a severe impact on the plant species and can cause great loss to economically important food crops.
Here, we will discuss damping off treatments and causes. One can also refer to this page to know about the common damping off symptoms.
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There are mainly two types of damping off processes, i.e., preemergence damping off and post-emergence damping off. It is caused by the fungus Fusarium equiseti which results in a dry, reddish-brown rot on the hypocotyl. This fungus is the main cause behind both pre-and post-emergence damping-off. Thus, damping off is a serious condition caused to the seeds and must be treated well.
Some of the common damping off symptoms that occur in various plant species are given below:
Rotting of seeds before the process of germination causing the seedlings to die before emerging is the first symptom of damping off. This process is also regarded as Pre-emergence damping-off.
Rotting of young seedlings around the crown region, resulting in softening of tissue, wilting, and falling over of plants is another common symptom known as Post-emergence damping-off.
In most cases, the seedlings turn to form a dull green colour along with the drooping of cotyledons. This is mainly caused by Pythium spp. which also causes the development of water-soaked lesions on the hypocotyls at the soil line resulting in seedlings wilt and collapse.
The occurrence of depressed tan to reddish-brown dry on elder seedlings is caused by Rhizoctonia solani, thus infecting seeds and affecting germination. These symptoms are similar to those caused by the Pythium species.
The infection caused by Acremonium spp. tends to develop symptoms usually between 7–10 days after seedling emergence. The infection can be found around the seed coat rand hypocotyl, which turns into a light yellow-brown colour. It develops into a dry red-brown rot within two to three days leading to seedling death.
Development of grey to reddish lesions which later turn coal black in colour. While in wet soil, a frosty coating may cover parts of the black lesion. This symptom is caused by Thielaviopsis basicola.
Although there is no specific damping off treatment, still use of various precautionary measures can definitely reduce the damping off caused by several pathogens.
We can easily prevent this issue with seedlings by providing good air circulation by use of a small fan. It can also be done by using a cracked lid or germination tray to allow the passing of fresh air. Other steps for preventing damping off include the following:
Use of biological fungicide Mycostop as a seed treatment to prevent seed or soil-borne diseases.
Usage of organic and good quality potting soil
To practise sterilizing your own potting soil in an oven.
To use light and fast-draining seed starter mix.
Planting seedlings in such a manner so that the soil surface is near the top of the container, thus allowing proper air circulation.
Prevent overcrowding of seeds by sowing them in a thin manner. Overcrowding may lead to humid and moist conditions.
Usage of seedling trays that provide water from below. Also, avoid watering the seeds past noon to allow the soil surface and the plants to be dry by evening.
Avoid overwatering of tender seedlings.
1. What are the Common Causes of Damping Off?
Ans. Damping off mainly occurs when old seed is planted in cold and wet soil. This damping off process is further worsened in case of poor soil drainage. The main cause of damping off, i.e., the fungal spores often live in the soil and affect the seedbeds. But it can also be avoided by providing high humidity levels, rich potting soils, and deep planting of the seeds.
2. Can a Seedling Affected by Damping Off Be Recovered?
Ans. No, any seedling which is once affected by damping off cannot be recovered to its healthy form. There is also no such cure for tiny seedlings that undergo damping off as they die very quickly. Therefore, it is very important to take prevention against damping off as it greatly affects the plantation of an area.
Planting young seedlings in a proper manner where the soil surface is near the top of the container is very important. This will thus allow proper air circulation among the seedlings, reducing the chances of damping off.