Seedling Troubleshooting - Yellowing + Necrosis

[JerseyTomatoChick]

Hi everyone!

I’m new here. I’m growing dwarf and indeterminate varieties in NW NJ (zone 5b/6a). I started a small handful of plants early for indoor container growing on a glazed porch. After a decent start, the first batch (8 seedlings) of Dwarf Beauty King started showing signs of chlorosis. Removal of the affected leaves seemed to help (photo from Jan 4), but a little over a week later the tips of the leaves appeared necrotic. A later batch of plants got affected, possibly by fungal gnat transmission (couple creeped in from the overwintering potted perennials, which are kept separately). The fungal gnats are long gone, but some of the newer seedlings which were only starting to develop true leaves are also showing necrosis on the tips of cotyledons.

Plants are watered moderately twice a week and allowed to dry fully. Fed once a week upon emergence of true leaves with liquid fish fertilizer. The lights (LED double banks, 5K) are approximately 5 inches above the leaves. Room temperature is approximately 68F. The surface is mulched with pine shavings for moisture control. Trays and pots aren’t new, but were washed with hot water and soap, and then soaked in a bleach solution for 1 hour. Planting medium: standard potting soil.

Note: Seed-born issues can probably be ruled out, since affected plants came from 3 different seed sources. Slight purpling on the Dwarf Beauty King leaves in later photos is due to them being quarantined on the porch with cooler night temperatures. All affected plants are kept separately from those which still appear healthy. I still have couple weeks before I start my main batch of seedlings, so it would be great to figure this out by then.
Thank you for your feedback!

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[Setec Astronomy]

I'm no help with your issues because I can't figure out my own seedling problems, but I'm very impressed with documentary reporting!

[MissS]

The first thing that I would do is to stop using the fish fertilizer while the plants are indoors and switch to some blue stuff. Many pathogens will grow on this medium. Fish emulsion is great outdoors but brings you havoc when used indoors. I would also remove your mulch for the time being to allow some air circulation to the soil. If possible, I would change your soil to get rid of whatever pathogens you now have growing there. However once the fish fertilizer is depleted the pathogens will more than likely dissipate.

Your plants also look to have a nutrient deficiency. Using some blue stuff will help to correct that. I would also add some Epsom salts to the feed at the mix of 1 T per gallon.

[Setec Astronomy]

Blue stuff?

[HL2601]

aka M****** Gro.

[Rockoe10]

I think you have a couple problems all at once.

One picture looks like Edema. Too much water.
Some look like nutrient deficiencies. Yellow leaves.
Others are definitely a mold or disease of some kind.

All of this could be caused by over exposure of moisture and not enough air flow.

[MissS]

@JerseyTomatoChick Blue stuff is any water soluble fertilizer. Most people would choose to use Miracle Grow but other brands can work just as well.

[bower]

The yellow leaves look like a N deficiency to me. Or roots may be starved of oxygen.
The necrosis grey stuff and water-soaked leaf appearance is another story. Looks nasty.
I would definitely remove the mulch so you can keep an eye on the soil surface. At present, if you have any water trapped at the surface between the shavings and the soil, it's a place for molds to grow, even though they look perfectly fresh on top. I would remove it and take a look at the soil surface; I would riffle it a bit too and loosen it up if or when the surface is dry. Aeration for your yellow leaved plants.
The grey stuff IDK. Could be soil borne and if so, probably better to chuck it and start with some fresh.
Do you top water or bottom water? I don't bottom water mine because they get too wet, although at 68F maybe not a problem.

Edited to add: the yellow tip and yellowing cotyledons I wouldn't worry about. It could simply be that the seeds were old, and there's not much juice left to get the plant started. They'll grow out of it no problem. Likewise a bad tip on a cotyledon is not usually a progressive necrosis, it could be that the seed didn't shuck entirely and bit into the end. But you can always nip the doubtful bit off with your fingernails and see if it doesn't recur.

[pepperhead212]

Welcome to the forum!

As others have said, this is probably a nutrient deficiency. And something that I do, with most of my seedlings, is use some of my hydroponics nutrients as the fertilizer - the type for vegetative growth, as they have all of the nutrients needed. I never have to add any extra N, or anything else, for that matter, though I do add some silica to tomatillos, as that helps strengthen the stems, and those are often weak, compared to other plants.

You say that they are topped with pine shavings. Wood, in general, is said to absorb N from the soil, so that may be a problem.

[JerseyTomatoChick]

Thanks for all the ideas, guys. I’ll be monitoring the flight for a week or so to see what happens next — luckily, it’s an early batch which isn’t numerous or essential to the main crop, so I can live with a wee bit of uncertainty as to the final outcome.

Couple additional notes:
- these were bottom-watered from the start (except for the sowing day)
- they weren’t too wet at any point (I stepped on that rake in the past, so I never water until thoroughly dried out, when pots are totally light and soil surface is dry)
- pine shavings are a very thin layer and I move them regularly to make sure the soil underneath isn’t funky in any way (in my experience, they help to reduce surface moisture rather than the other way around, when seedlings are bottom-watered, but for now they’ve been removed until thoroughly dried after rinsing — see below.)

After consulting with couple other forums, a hypothesis for excess salt content in the medium has been suggested. I once had a similar issue with added coco coir years ago and some of the symptoms indeed looked similar. Possible remedies included repotting or rinsing. Since this is a small batch, I can afford an experiment (and associated possible losses), so I went the rinsing route. They all got thoroughly soaked multiple times (from the top this time, naturally — no way to avoid that), then placed on a heating mat for 24 hours with a fan going constantly. Too early to tell, but they already look much better. Regardless of the outcome, I’ll post updated photos in a week or so (when there will be a visible difference).

Thanks again!