What is Damping Off?

“Damping off” is a term used to describe a number of different disease conditions that cause seeds and young seedlings to die soon after they begin to grow.

The term is often used for a number of conditions that causes seedlings to fail before or after they emerge from the soil. It’s a very common problem in gardening and agriculture, causing a significant decrease in the number of viable plants.

Damping off can occur at different stages of plant development, but it most commonly affects seeds and young seedlings. There are two primary forms of damping off: pre-emergence and post-emergence.

Causes of Damping Off

Pre-emergence Damping off

As the name implies, this occurs when the pathogens attack the seeds before they germinate or the seedlings before they break the soil surface. The seeds may rot and never germinate, or the seedlings may die before they emerge from the soil. This form of damping off can result in bare patches in the seeding tray or in the field where no seedlings have emerged.

Post-emergence Damping off

This malady affects seedlings after they have emerged from the soil. The young seedlings suddenly wilt, their stems become water-soaked and thin, often at the soil line, and then the seedlings topple over and die.

Both forms are caused by the same types of fungal pathogens, primarily species of Pythium, Rhizoctonia, and Fusarium. These fungi are present in most soils, but they become problematic when conditions are overly wet and soils are poorly drained. High humidity, poor air circulation, and low light levels can also contribute to the problem.

Both seeds and young seedlings are highly susceptible, with the condition becoming visibly noticeable often once the seedlings have emerged and then suddenly wilt or collapse.

Damping off is usually caused by a variety of soil-borne fungal pathogens such as Pythium, Rhizoctonia, and Fusarium, though it can also be caused by some types of bacteria and molds. These pathogens infect the seedlings, causing them to rot and die. They are generally more problematic in wet, cool conditions and in soils with poor drainage.

Fungal Pathogens That Cause Damping Off

1. Pythium: Pythium species are often referred to as “water molds” due to their affinity for wet, waterlogged conditions.
2. Rhizoctonia: This fungus is typically referred to by its scientific name. It causes diseases such as root rot, wire stem, and damping off.
3. Fusarium: Similarly, this fungus can cause a wide range of diseases, including wilts, rots, and damping off. It varies from “Fusariaum wilt” which can affect plants at any stage of growth.
4. Phytophthora: These are another group of water molds similar to Pythium. They are responsible for diseases like late blight in potatoes and tomatoes.
5. Botrytis: Also known as “gray mold”, this fungus can attack many different types of plants, often affecting plant parts above the soil line but it can contribute to damping off as well.

These are just a few examples of the fungi that can cause damping off. There are many others, and each one has a slightly different life cycle, preferred hosts, and environmental conditions. It’s also worth mentioning that these fungi don’t just cause damping off – they can cause other plant diseases as well. This is why it’s so important to maintain good sanitary practices in your garden and to keep your plants as healthy as possible.

Damping Off Symptoms

Common symptoms of damping off include:

1. Seeds may fail to emerge from the soil.
2. Seedlings may collapse with a soft rot at the soil line.
3. Roots of older plants may become infected, turning brown and rotting.
4. Seedlings may look pinched or tight at the soil line, often falling over.
5. Seedlings often have a grey, moldy appearance.

Treatment for Damping Off

Unfortunately, there is no known remedial treatment for damping off. That means that most plants that are affected will not make it.  

As seedlings get older, they become less susceptible to damping-off pathogens,^[2]https://ipm.ucanr.edu/PMG/PESTNOTES/pn74132.html but if affected seedlings are not known to revive, thus prevention is the best bet.

Damping Off Prevention

Prevention of Damping Off in Potted Seedlings

Preventing damping off involves a combination of good cultural practices and, sometimes, the use of fungicides. Here are some measures you can take:

1. Drainage: Ensure your containers have excellent drainage.
2. Fungicides: If you’re having a lot of problems with damping off, consider using a fungicide designed for use on seedlings.
3. Sanitation: Use clean pots and trays, if using containers. Sterilize used containers with a 10% bleach solution.
4. Soil: Ensure you’re using a fresh, good quality sterile seed-starting mix.
5. Spacing: Plant seeds at the recommended spacing to improve air circulation.
6. Temperature: Keep your seeds and seedlings at the optimal temperature for the particular species. Warmer conditions can often help reduce the impact of damping off.
7. Watering: Overwatering can create an ideal environment for fungi to thrive. Water seedlings from below if possible to avoid wetting the stem and leaves, and let the top of the soil dry out between watering.

Prevention of Damping Off in Garden Beds – 8 Tips

1. Drainage: Ensure your garden beds have excellent drainage. Adding organic matter to your soil can help improve its structure and drainage.
2. Fungicides: If you’re having a lot of problems with damping off, consider using a fungicide. Be sure to choose one that’s safe for seeds and seedlings and follow the instructions on the label.
3. Location: Plant your seeds in an appropriate location for the particular species. Full sun locations often dry out faster and are less likely to promote fungal growth. Also, plant at the appropriate time for your crop to avoid having your seeds sit in cold, damp soil for too long.
4. Rotation: If possible, avoid planting the same crop in the same location year after year. Crop rotation can help prevent the buildup of pathogens in the soil.
5. Sanitation: Ensure your garden beds are clean and free from plant debris. If you’ve experienced problems with damping off before, consider solarizing your soil to kill any lingering pathogens. This involves covering the soil with a clear plastic tarp and letting it heat in the sun for several weeks.
   See also, red plastic mulch for tomatoes.
6. Spacing: When sowing seeds directly into the garden, follow the recommended spacing guidelines. Overcrowding can lead to poor air circulation and increased disease problems.
7. Soil: Healthy well-draining soil is essential for damping off prevention.
8. Watering: Avoid overwatering your seeds and young seedlings. Soggy conditions can promote fungal growth. Instead, aim for consistent moisture. Using a watering can with a rose attachment can help evenly distribute water without causing erosion or overly wet conditions.

For fungicides, consider natural remedies like cinnamon for plants.

Remember, once a plant has been affected by damping off, there’s not much of anything that can be done to save it. That’s why prevention is so important.

By following these steps, you can increase the chances of your potted and direct sown seeds growing into healthy, mature plants.

What Plants Are Most Vulnerable to Damping Off

While damping off can affect a wide variety of plants, it’s most common in seedlings of vegetables, flowers, and trees. Some types of plants are more susceptible than others. Cool-weather crops like lettuce and peas are often more susceptible, especially when planted in cool, wet soil.

However, every plant species has different resistance levels to pathogens, and their susceptibility can also depend on the environmental conditions in which they’re grown. Optimal growing conditions for each plant variety can reduce the chances of damping off. Therefore, understanding your plants and their specific needs is key to preventing damping off.

Remember, once a plant has been affected by damping off, there’s not much that can be done to save it. That’s why prevention is so important.