An Essential Guide to Pythium Damping Off



Pythium Damping Off is a disease caused by water mold fungi that attack newly germinated plant seedlings. It is particularly devastating to young plants, causing the shoots and stems to rot and collapse, resulting in the death of the seedling. Prevention is key to controlling the spread of this disease. Proper management of soil, water, and other environmental factors can go a long way in preventing Pythium damping off infections.


Pythium Damping Off


Pythium damping off is a fungal disease caused by species of the water mold Pythium. It primarily affects young, emerging seedlings, especially those grown in greenhouses. The disease is characterized by seedlings’ wilting, yellowing, and eventual death. Pythium damping is mainly caused by inadequate drainage, soggy soil, and high humidity. Pythium is spread by water and can be found in soil or water. Symptoms of this disease include wilting of seedlings, lesions on stems, a dark discoloration of plant crown or roots, and root rot to being unable to emerge from the soil. In severe cases, seedlings may collapse and die within a few days of germination. (Chen)


How to Identify Pythium Damping Off in the Garden


Once the presence of Pythium damping off is confirmed, it is important to take steps to eradicate the problem. The most effective solution is to remove and discard affected plants, as they will not recover. In addition, the soil should be treated with fungicides to kill any remaining Pythium spores. Fungicides can be purchased at most garden supply stores and come in liquid and powder forms. If using a liquid fungicide, it is important to water the area well before applying it. This will ensure that the fungicide penetrates the root zone where it can effectively fight off Pythium damping off.


Cultural practices can also help prevent future infestations of Pythium damping off in gardens. Keeping beds free from weeds helps reduce pest populations and prevents fungal pathogens from taking hold. Additionally, good drainage practices must be followed to ensure adequate aeration of the soil and to prevent waterlogging. If a container garden is present, be sure to use a potting mix that is sterile and free from pathogens. Crop rotation can also help reduce the risk of Pythium damping by preventing new spores from introducing to previously infested areas.


Overall, due to the destructive nature of Pythium damping off, gardeners must take steps to identify and eradicate this fungal pathogen before it causes significant damage. Taking necessary precautions such as treating affected soils with fungicides, practicing proper cultural practices, and avoiding overcrowding will go a long way toward keeping gardens healthy and free from Pythium damping off. With some preventative measures, gardeners can enjoy healthy and vibrant gardens for years to come. (Elad)


Ways to Prevent Pythium Damping Off in the Garden


Preventing Pythium damping off is key to a successful crop. Proper sanitation measures, such as washing hands and equipment after use, can help to reduce the spread of the disease. It is also important to practice good hygiene in the nursery, such as avoiding contaminated tools and equipment. Optimum growing conditions, such as using suitable soil temperature and moisture levels, avoiding watering, and improving air circulation for the crop, can also help reduce the risk of infection. Applying fungicides or using bio fungicides can also effectively control Pythium damping off.

Additionally, using raised beds or containers to grow crops can help limit the spread of the disease and improve soil drainage. These measures can help ensure crops are free of Pythium damping off and protect them from possible yield loss. Furthermore, disease-free seeds and resistant cultivars can also help control the spread of Pythium damping. (H Chauoi et al.)


Treatment Options for Pythium Damping Off


Treating Pythium damping off can be a difficult and daunting task, as the fungus is highly resistant to most commonly used chemical fungicides. Fortunately, several viable treatment options are available to those affected by this fungal pathogen. 


One of the most successful treatments is combining chemical and biological control measures. Chemical fungicides are best applied as a preventative measure as they do not provide 100% protection against Pythium damping off. There are two primary types of chemical fungicides available: contact and systemic.


  • Contact fungicides work by forming a coating on the surface of plants, preventing the fungus from entering; however, these can be washed away easily with rain or irrigation, thus requiring frequent re-application.


  • Systemic fungicides penetrate the entire plant, providing better protection but can be more expensive and difficult to use in certain situations.


In addition to chemical control, biological control can also be employed as a treatment for Pythium damping off. This form of pest management uses natural organisms such as bacteria or fungi to attack and feed on the fungus, leading to its death. For instance, Pseudomonas fluorescens is one bacterial species known to suppress Pythium damping in crops such as cucumbers and tomatoes. Similarly, Trichoderma harzianum is a beneficial fungus successfully used to treat suppressed areas within fields where Pythium damping has occurred. 


Finally, cultural methods are also important for preventing and treating Pythium damping off. These include crop rotation to break disease cycles, using resistant varieties of crops, and avoiding over-irrigation, as excess moisture can make plants more susceptible to the fungus. Moreover, removing and disposing of infected plants and debris is essential to prevent the spread of this pathogen. 


By combining chemical, biological, and cultural methods, growers can effectively manage and eradicate Pythium damping from their fields. While chemical control measures provide a quick fix for the fungus, biological and cultural control measures are more sustainable in the long run. They can help protect crops from Pythium damping off for many years. (Weiland et al.)




Pythium damping-off seriously threatens emerging crops and can devastate crop yields. It is important to be aware of the causes and symptoms and take preventative measures to ensure a successful yield. With proper sanitation practices, optimum growing conditions, and fungicides or bio fungicides, growers can reduce their risk of Pythium damping off.



Chen, Weidong. “Factors Affecting Suppression of Pythium Damping-off in Container Media Amended with Composts.” Phytopathology, vol. 77, no. 5, 1987, p. 755.,

Elad, Yigal. “Possible Role of Competition for Nutrients in Biocontrol of Pythium Damping-off by Bacteria.” Phytopathology, vol. 77, no. 2, 1987, p. 190.,

Suppression of the Plant Diseases, Pythium (Damping-off), Rhizoctonia …

Weiland, Jerry E., et al. “Sensitivity of Pythium Irregulare, P. Sylvaticum, and P. Ultimum from Forest Nurseries to Mefenoxam and Fosetyl-Al, and Control of Pythium Damping-Off.” Plant Disease, vol. 98, no. 7, 2014, pp. 937–942.,

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