Damping Off Disease: What It Is And How To Prevent It
I remember a year not long ago when we started seeds in December. But by the time January rolled around, some of our seedlings weren’t looking so good. While most of the seeds did sprout, many of the seedlings didn’t live long enough to acquire a second set of leaves. If this has happened to you, it may be damping off disease.
Damping off disease may not be a familiar term for the beginning gardener. But seasoned gardeners know that it can be devastating. Yes, damping off disease happens to even the most experienced gardener. So don’t feel bad if this has happened to you. While it can be disappointing to experience, it’s not the end of the world. And it certainly shouldn’t be the end of your gardening dreams. There are ways to prevent it!
If damping off disease is new to you, grab a cup of coffee while we discuss what it is, why it’s bad and how to avoid it.
What is “damping off disease”?
According to Wikipedia, “damping off” is “a horticultural disease or condition, caused by several different pathogens that kill or weaken seeds or seedlings before or after they germinate. It is most prevalent in cool, wet conditions.”
Simply put, damping off is a disease that affects young seedlings, sometimes to the point where they rarely live long enough to see the great outdoors. And it can affect both vegetables, fruits and flowers. The cool, wet conditions are usually a result of growing seeds in large quantities without adequate light, heat or air circulation. Young seedlings are highly susceptible to this infection. It is also known as “root rot” or “crown rot” in more mature plants.
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What does damping off disease look like?
In most cases, infected seeds will germinate and come up fine. However, it will be obvious within a few days that something is wrong. The first set of leaves look water-soaked and mushy. The stems of seedlings can be so thin they resemble thread and will eventually fall over at the soil line. Young leaves quickly wilt and turn gray or brown. Roots may appear stunted or have grayish-brown spots. If a large number of seeds fail to germinate or produce a sprout, damping off disease may be the culprit.
What causes damping off disease?
Damping off disease is caused by a fungus or mold that can survive in soil and plant debris. It can make it’s way into the seed tray in several ways, usually through pots and tools that weren’t properly cleaned between use. It can also travel in re-used potting soil. All of these items can harbor pathogens that are deadly to young sprouts. Spores can blow in on a breeze. They can also be carried by insects like fungus gnats or by splashing irrigation water. Additionally, it can also be transmitted on dirty hands, contaminated tools or garden hoses that have been in contact with contaminated soil.
Once a seedling is infected, the pathogens easily move from plant to plant, growing through the soil or in the irrigation water. Soil from the garden often contains small amounts of the damping off pathogens. If you use garden soil to start seeds, you may have unknowingly introduced harmful pathogens into your seed trays and pots. Therefore, it’s important to start with good soil or use a quality seed starting mix.
Seeds planted directly in the garden can also suffer from damping off. This happens when seeds are planted in soil conditions that are too cool for germination. It can also occur when the weather turns cold and wet right after planting. Hello surprise frost! Low light, over-watering and high salt levels from over-fertilizing can contribute as well. Really, any condition that slows plant growth can increase damping off.
How to prevent damping off:
I hate to be the bearer of bad news but seedlings infected by damping off rarely survive past the sprouting stage. It’s not unusual for an entire tray of seedlings to be infected or die as a result of damping off. The good news is that once plants have mature leaves and a well-developed root system, they are better able to resist this disease.
Prevention is the key!
- Use good soil: Nearly every bad thing that happens to young plants can be avoided by using good, healthy, well-draining soil. Mold spores can travel on the breeze and land in your garden soil, pots or old seed bed. So you never want to re-use soil or potting mix to fill seed trays. So, what if the local garden center is out of potting soil or seed starter mix? You can sterilize your used potting soil in the oven. Place soil in an oven-safe pan, cover with foil and bake at 180-200 degrees for thirty minutes. Just be aware that sterile soil won’t grow much so you’ll need to add some well composted manure prior to planting. You can learn more about different soil types and how to have good soil here.
- Use clean containers: For inexperienced gardeners, washing pots and grow trays may seem unnecessary. But spores can be transmitted on pots and grow trays that still contain bits of soil from a previous growing season. Make it a habit to clean them after each use. After cleaning, rinse them in a solution of 1 part household bleach to 9 parts water for about 30 minutes. If you’ve lost plants previously to this disease, you know how sad it is to see your hard work come to nothing. Taking a few extra minutes to clean your equipment will go a long way toward avoiding this disease.
- Use clean tools: Any tool that will come in contact with seeds or soil should be cleaned properly. A good wipe-down with rubbing alcohol after each use should be sufficient. Store tools in a clean location when not in use. You can learn more about care and maintenance of garden tools here.
- Don’t over water: Whether you use soil, a potting mix or pellets, you don’t want the soil to be overly wet. In fact, the moisture level to shoot for is similar to a wrung-out sponge. Once the seeds have sprouted, remove the lid or covering from the seed tray. If all seeds have not yet sprouted, just prop it up an inch or so. This will cut down on mold and mildew developing. Keep the roots moist (not soggy) and the plant dry by watering from the bottom.
- Fill soil to the top: Whether using starter trays or small pots, filling them all the way to the rim will ensure proper air circulation once the seed sprouts. If the sprouts don’t reach above the rim, they’re not going to get much air. I recommend using an oscillating fan turned on low.
- Sow seeds thinly: Seedlings need space to grow and move, so avoid over crowding. Again, an oscillating fan can help a lot. Not only will it help ward off this terrible disease, but air movement from the fan also helps strengthen the young stems in preparation for a breezy, outdoor life.
A few more tips…
- Use a heat mat under the trays to keep the soil warm. Many starter tray systems come with a heat mat. The best temperature for indoor plants is between 70-75 degrees. Of course, this temperature varies depending on the plant and the time of year. But if you’re planting directly in the soil for a spring or summer garden, wait until soil has reached 70 degrees for several consecutive days. This will provide the best chance for successful germination. Learn more about seed starting here.
- Make sure seed pots have good drainage holes.
- It may be a pain but try to keep nozzle heads out of the dirt. Remember, spores can hitch a ride on anything that comes in contact with contaminated soil.
- Pay attention to water temperature when watering young seedlings. Ideally, water should be between 68-77 degrees. Water that is 50 degrees or lower slows plant growth and increases the opportunity for infection.
- Do not apply fertilizer to seedlings. If you used good, clean soil, they shouldn’t need it until they’re ready for transplanting outdoors.
- For indoor seedlings, provide 12 to 16 hours of light from a soft white fluorescent light or grow light. There are only so many hours of daylight coming through your windows so you need to supplement. By the same token, make sure you turn the grow light off at night. Even seedlings need their beauty sleep!
- If seeds are started outside or seedlings later transferred to the garden, harden off the plants first so they gradually become acclimatized to the outdoors. Also, make it a habit to water in the mornings. This ensures the soil surface and the plants are dry by evening. when temps may be cooler. If you water deeply, you should only need to water once or twice a week, depending on the daily temps.
A final thought…
Unfortunately, there is no cure for plants once they’ve acquired damping off disease. Once they have it, all you can do is pull them up and start over with clean pots and clean soil. However, you can easily prevent the problem by following the simple tips mentioned above. The biological fungicide Mycostop may also be used as a seed treatment to prevent seed or soil borne diseases. However, I would start with the simplest options first….but that’s just me. The healthier your plants are from the beginning, the better equipped they are to resist disease. As the old saying goes, an ounce of prevention is worth a pound of cure!
Have you had a problem with damping off disease? If I missed anything or you have further questions, feel free to share. Good gardeners are always willing to learn and share what they know. So go ahead and leave your comment below. I’d love to hear from you!
Until next time,
lisa
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