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Edible Gardening Series: Question of the Week – Damping-off

By Sarah Bostick and Carol Wyatt-Evens

Gardening in Florida can be incredibly rewarding and incredibly frustrating, at the same time. If you are new to the region, you soon learn that gardening in the Sunshine State can quickly become a full-time job. While our subtropical climate is perfect for growing an abundance of different vegetables, fruits, and herbs, it also can present some overwhelming challenges.

We can help! UF/IFAS Extension Sarasota County agents and staff have created an online edible gardening resource center. The website features short videos from our 25-episode “Edible Gardening Series” webinars, along with blog posts and resources lists for episodes. Get help on an array of topics that befuddle many gardeners.

 

This week’s Question of the Week:
What causes damping-off disease in my winter garden and how can I prevent it?

Growing during the coolest months of the year comes with its own unique challenges. One of those challenges are plant diseases that need cool temperatures to thrive.

Many farmers and gardeners have experienced “damping-off” in their seedlings and directed seeded crops. Damping-off is a generic term that is used for a whole list of fungal infections that have a very similar impact on plants. Some of the fungi that cause damping off need cool/cold wet soil to thrive.

The fungi that cause damping-off may be present in the growing medium that you use to start seedlings or the cold, wet soil you are planting into. Do not re-use potting mix that has produced plants with signs of damping-off.

 

Some of the fungi that causes damping-off causes the main stem of young plants to rot, starting at the soil line. Photo credit: Sarah Bostick

Some of the fungi that causes damping-off affects young plants after they emerge from the soil. How do you know if you are

experiencing this type of damping off? You will see plants that are starting to rot or become extremely thin where the main stem meets the soil.

Some fungi impacts the roots of young plants. The plants will often look stunted, weak, and droopy and may quickly die. When you pull these plants out of the soil, you will discover that they have little to no root system.

And last but not least, some types of fungi attack the seeds as they start to germinate. This type of damping-off causes lack of germination or bare patches in your garden or seedling trays. You may also see white or grey mold growing on the surface of the soil.

To the untrained eye, damping-off can look similar to some non-disease issues in young plants including very wet soil (plants can become starved of oxygen), very high levels of fertilizer, very cold or very hot temperatures, herbicide damage, and more. One indication that you are experiencing damping-off rather than one of the above issues is that the effects of damping-off generally appear to be a bit random or scattered. For example, if three of your ten young kale plants look like their main stem is dying and the rest of your kale plants look just fine, the issue is much more likely to be damping-off than cold damage. Cold damage should impact all of your kale equally.

So how do you deal with damping-off?

Prevent it. It is very difficult to control once it has set in.

Preventing damping-off:

Trays of seedlings with damping-off

  1. If you are starting your own seedlings, sanitize the containers you are starting seedlings in before using them.
  2. Do not re-use potting mix unless you thoroughly sanitize the potting mix first.
  3. If you like to save seeds, make sure that you are starting with disease-free plants. The best way to ensure that you are starting with disease-free seeds is to purchase your seeds from a reputable seed company.
  4. Learn about the planting requirements of what you are growing and follow the seeding recommendations. Seeds planted too deep or too thickly are more susceptible to disease.
  5. If you are starting seedlings in a cold part of your house, you may want to invest in a heat mat for your trays – this will help increase the temperature of the potting soil enough to prevent cold-loving damping-off fungi.
  6. Provide your plants with an appropriate amount of water. Damping-off fungi needs wet soil, so whether you are starting plants in trays or directly in the ground, make sure that the soil has time to dry out between waterings.

 

The Edible Gardening Series and blog series is a partnership between the following UF/IFAS agents and Sarasota County staff:

  • Sarah Bostick, Sustainable Agriculture Agent
  • Carol Wyatt-Evens, Chemicals in the Environment Agent
  • Mindy Hanak, Community & School Gardens Educator
  • Kevin O’Horan, Communications Associate

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