Damping Off Questions

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Bronx
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Damping Off Questions

#1

Post: # 10641Unread post Bronx
Sun Feb 16, 2020 9:27 am

Just had the first of my tomato seeds poke their heads out of the mix so I figure this is a good time to ask a couple damping off questions.

I've heard that spraying a diluted hydrogen peroxide solution on the seedlings can prevent damping off. My question is when is a good time to start this, when the seedlings first come up, when they get their first set of true leaves or some other time? Also, how often to spray them?

I had an issue with damping off for the first time last year so I'm not too experienced at preventing it or looking for signs of it before it's too late.

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MissS
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Re: Damping Off Questions

#2

Post: # 10649Unread post MissS
Sun Feb 16, 2020 10:03 am

First, it is important not to have your seedlings too wet. More importantly, keep the soil surface on the dry side. Water from the bottom only and allow the moisture to wick up. Allow your pots to dry out before you water again.

I have not had much success at using hydrogen peroxide, so I am the wrong person to answer that question.

In my old house I had a horrible problem with mold and damping off. Nothing would help unless I used chemicals and I don't like to do that so much. I found a product by Mosser Lee called No Damp Off Seed Starter. After I began using this, I never had an issue with damping off again. https://www.mosserlee.com/product/530_N ... edium.aspx
~ Patti ~

kath
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Re: Damping Off Questions

#3

Post: # 10687Unread post kath
Sun Feb 16, 2020 11:26 am

My plan is to use a fresh bag of soilless mix which I try not to oversaturate, sterilize the containers with water/bleach solution, make sure the seeds have good contact with the mix and cover them with enough mix so that I can let the top layer dry out a bit before rewetting, and I do admit I water from the top, especially until germination is complete. If I feel the need to use covers until germination, I will spray the surface with water/H2O2 and prop up the cover a bit to allow air flow and daily remove extra water that might condense on it. I watch for any signs of "fuzzy stuff" appearing on top of the mix and spray the surface completely with a water/H2O2 mix as often as I spot anything. As soon as germination begins, I ditch any covers for good and get the tray under lights for 16 hours/day if it's too cold to put them outside in the sun during the day. I start sowing tomatoes later every year- this year no sooner than mid-April. Never had a major issue with damping off. Some folks use fans for air flow and to make sturdy seedlings, and I guess this would help, too, although I don't do it.

Here is a link which gives some ideas about water/bleach and water/H2O2 ratios: http://pcmg.ucanr.org/files/171557.pdf

I've used stronger solutions of H2O2 without issue, but I'm more careful not to make it too strong once seedlings have sprouted. Still, I never make it weaker than about 10:1. If I were you, I'd spray the soil surface and edges of the container now.

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peebee
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Re: Damping Off Questions

#4

Post: # 10711Unread post peebee
Sun Feb 16, 2020 12:34 pm

I've tried different things like sprinkling cinnamon over the soil, using weak chamomile tea only as the water, etc but nothing worked until I read a TVille member's method (sorry I forgot his name but I am forever I indebted to him for this): sow the seeds in the oil absorbing granules sold in auto supply stores. It goes by many names depending on the maker, often strewn on driveways. It's cheap & one bag will last forever if you mass sow like I do. Plus separating the seedlings is a breeze. You'll need to cut out paper towels to cover the bottom holes as the grains will seep out. Bottom watering only if course & they can dry out so you'll have to monitor every few days. I have never had damping off in years. Highly recommend this.
Zone 10, Southern California
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brownrexx
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Re: Damping Off Questions

#5

Post: # 10761Unread post brownrexx
Sun Feb 16, 2020 3:34 pm

Damping off is caused by a fungus and it will grow if it is given the conditions that fungus loves - cool and damp.

I start my seeds by using new plastic cell packs, sterile soiless mix and I keep my entire set up in my 74° sunroom. I know that a lot of people swear by bottom watering but I do not. I feel that damp is damp whether the water came from the top or the bottom, the mold spores will not care. If they get moist and have cool conditions then they will grow. Another thing that I don't like about bottom watering is having standing water in the area of my seedlings.

I never have damping off issues but I do not grow hundreds of plants like some here, so I have room in the warm part of my house to start seeds. I think that people starting seeds in basements or garages have more of a risk of damping off due to the cool conditions.

I also use sterile media and brand new pots so neither of these should have any mold sores in them. If you use pre-used pots, then you should sterilize them by washing with a 10% bleach solution or a vinegar solution to kill any dormant spores adhering to the pots.

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SQWIB
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Re: Damping Off Questions

#6

Post: # 10793Unread post SQWIB
Sun Feb 16, 2020 6:00 pm

Use a fan.
Thigmomorphogenesis is the response by plants to mechanical sensation (touch) by altering their growth patterns. In the wild, these patterns can be evinced by wind, raindrops, and rubbing by passing animals.

Wind (I use a fan here) is a Morphogenic Stimulus and strengthens stalks by resistance as well as increasing transpiration of the plants by dehydrating the leaf surface.
The transpiration causes rapid mineral and water uptake increasing the thickness of the stem.

Using a fan also helps keep the surface of the soil dry to prevent mold, fungus Gnats and damping off.

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brownrexx
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Re: Damping Off Questions

#7

Post: # 10833Unread post brownrexx
Mon Feb 17, 2020 7:49 am

I don't use a fan on my seedlings but I have noticed a marked increase in the stem thickness after I put the trays outside for a few hours a day to get some fresh air and sun. There is almost always a slight breeze at that time of year. For the first couple of days that I put them out, they seem so delicate but they thicken up and look much more sturdy in just a few days.

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MissS
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Re: Damping Off Questions

#8

Post: # 10837Unread post MissS
Mon Feb 17, 2020 8:43 am

Fans are one of the best things for tomato seedlings. They make strong sturdy plants and help prevent disease. My seedlings were tall thin stalked plants until Raybo had me start using them.
Another thing that works well in preventing damping off is to use DE as a planting medium or at the very least cover the top on the growing medium with it. This also helps to control fungus gnats.
~ Patti ~

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worth1
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Re: Damping Off Questions

#9

Post: # 10838Unread post worth1
Mon Feb 17, 2020 8:46 am

The 7% solution always works for me.
Worth
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peebee
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Re: Damping Off Questions

#10

Post: # 10862Unread post peebee
Mon Feb 17, 2020 12:16 pm

MissS wrote: Mon Feb 17, 2020 8:43 am
Another thing that works well in preventing damping off is to use DE as a planting medium or at the very least cover the top on the growing medium with it. This also helps to control fungus gnats.
Thank you MissS that was the word I was looking for, DE or diatemaceous earth. Which is the what the oil absorbent is made of except the ones in the auto stores are not the fine powdered types common in DE used for insect control, for example. I don't know what it is about DE that prevents damping off but I'll never use anything else again. Plus the huge bag will last me forever.
Zone 10, Southern California
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Shule
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Re: Damping Off Questions

#11

Post: # 10900Unread post Shule
Mon Feb 17, 2020 4:30 pm

I'm not sure about hydrogen peroxide and its efficacy there, but my personal experience says that using a 2700k CFL by your plants (and/or having some strong sunlight) can prevent it. Higher color temperatures don't seem to prevent it (whether or not they help plants grow better). Avoid using outdoor soil indoors, and avoid using old soil. Avoid having the soil line be too far below the top of the containers.

I imagine having a gentle fan for some ventilation would help, too.
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Bronx
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Re: Damping Off Questions

#12

Post: # 11183Unread post Bronx
Wed Feb 19, 2020 6:41 pm

All great tips and advice, much appreciated.

Unfortunately for the forseeable future I pretty much have to top water the seedlings. I foolishly bought a Costco size bag of paper dixie cups for seed starting, and they will disintegrate if I try to bottom water the seedlings in these things. After buying them I realized my mistake but hate to waste these, can't really think of anything else to use them for. For the past 2 years I double up on them to try to get rid of them as quickly as possible, but it's a HUGE bag and I still have lots of these cups. Oh well, at 62 still learning a thing or two.

And with overwatering, guilty as charged. I really need to pay more attention to that. That could have been the cause of my damping off issues last year.

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asaump
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Re: Damping Off Questions

#13

Post: # 22236Unread post asaump
Thu Jun 11, 2020 12:41 pm

+1 on the fan. I run mine for about an hour 4-5 times a day.
Ken

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Re: Damping Off Questions

#14

Post: # 22254Unread post pepperhead212
Thu Jun 11, 2020 4:57 pm

I'm another fan user, maybe 10 days or so after the seedlings appear. First, an hour of an oscillating fan, 3 different hours in the day, later increasing it to every other hour, until leaving it off overnight. I also add silica when watering the seedlings - a very small amount (about 1/2 tsp/gal) of the mix I got for my hydroponics, to strengthen stems. Ever since I started using it, tomatillos have had very strong stems, while before, I used to have a problem with the stems breaking, and was always staking them up in the pots. No idea if it helps with damping off, but the stems seem stronger on everything.

When getting my seed starting mix ready, I always add some extra perlite, for better and quicker drainage, and moisten the mix the first time with some of the micorrhyzae water mix (made with some filtered water, so as not to kill it with chlorine). KOW, I have yet to have a damping off problem.
Woodbury, NJ zone 7a/7b

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Re: Damping Off Questions

#15

Post: # 22255Unread post Cole_Robbie
Thu Jun 11, 2020 5:27 pm

Somewhat similar to the de idea, I cover my seeds with vermiculite when I start them. The top layer of media at the soil line is key. Vermiculite holds more air, discouraging anaerobic bacteria like pythium.

The amount of organic matter in your mix needs to vary directly with the temperature. Pro mix is typically sterile for this reason, making it work in the cold. Organic mixes can be great, but the temperature needs to be high enough so that the correct bacteria are grown.

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asaump
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Re: Damping Off Questions

#16

Post: # 22829Unread post asaump
Thu Jun 18, 2020 1:01 pm

I would punch a few holes in the bottom of the cups and bottom water. Set the cups in some plastic trays. The 1020's work well and can be had for little money.. I would think it a cup is designed to hold water to drink from they would hold up a bit of bottom watering. They would only have to sit in water long enough to soak up the water into the soil.
Ken

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Re: Damping Off Questions

#17

Post: # 22835Unread post Labradors
Thu Jun 18, 2020 2:21 pm

I top water my tiny seedlings every day using a teaspoon. It's just enough for them and hasn't caused any damping off. I start them off in Pro-mix with no nutrients.

Linda

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arnorrian
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Re: Damping Off Questions

#18

Post: # 22914Unread post arnorrian
Fri Jun 19, 2020 1:56 pm

Syringe is handy too.
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edweather
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Re: Damping Off Questions

#19

Post: # 23063Unread post edweather
Sun Jun 21, 2020 8:18 am

I have had some damping off in the past, but not very often. Fast forward to this year, a particularly bad fungus year. I am starting watermelons outside in containers from seed. Have NEVER had any damping off problems with them. BUT, this year, it is impossible to start them, and am close to giving up. I think damping off is a disease, possible fungal or bacterial in nature, and is tough to fight. The years I had it, nothing seemed to work to fight it. I just hope it doesn't happen. Like I said, it's been a very bad fungal year here in Georgia, and VIOLA, damping off too. The ones that do survive, are dying anyway from disease.
Southeast GA, USDA 9a, HZ9, Sunset Z28

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