Young onions problem

First, I want to say I am not a novice in the matter and successfully started my onions from seeds several years in a row. Never lost a single one other than to accidental pulling.
This year is much different. It started with box of Patterson onions about a week after emerging. The top started to wilt, like it was affected by direct sun or frost. There is no “black leg”, roots still look nice and healthy. If I cut the bad top, it may even push a new leaf up, but doesn’t recover. Eventually it just dries out. I already lost about half of the seedlings. The other box of Red Wing is a bit better, but it took longer time to emerge and it started the same route as Patterson - wilting without any visible damage to the stem or roots.
I am almost sure I will have to buy my planting onions this year. But what I try to figure, what kind of disease it is and if it is safe to plant them out to the garden if some survive?

I think I found it… (sigh)
Onion Smut
Because I didn’t have it before neither indoor nor outside, I suspect seeds. Too bad.


Nasty onions read onion smut :thinking:


@galinas I can’t tell for sure from your photos, but looks like it is mostly starting from the tips of your onion seedlings drying out and turning brown and progressing from there. The roots and lower stems look ok from what I can see. This doesn’t strike me as a biotic disease and definitely not onion smut. Another clue is it is affected multiple varieties, so unlikely to be seed-borne. I think it is something like high salts in your potting mix, temperature too warm or air is too dry. I cover my pots of onion seeds with plastic until they germinate to keep the moisture constant, and if I wait too long, I get something similar on the ends of the ends of the leaves after exposure to dry air, but they usually survive just fine so long as it is just leaf tips.

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I wouldn’t say it starts with tip - it is like whole leaf gets soft, like it was burned by sun or frozen. If you look at the second picture - right leaf is already wilted, it is not that visible on picture, but when you touch it, it feels. The mix I use I make myself and I always make it that way - 1 part of own compost, 1 part of pro-mix, 1/2 part of vermiculite and 1/2 part of perlite + Osmocote in recommended rate by volume. Onions germinated at about 73F under the glass, after that they were moved to 62F under fluorescent lights. Nothing special that I wouldn’t do any other year. I have lettuce and parsley started in the same mix - they do not show any signs of distress. But it always could be something that affects only onions - either in pro-mix or in compost. I stared a new batch in strait pro- mix, want to see if it shows the same signs. I can’t decide what to do with those that survived. The Patterson almost gone, 20% left probably. The Red wing only lost about 10%. I debate with myself, should I keep what left and plant in the ground or discard just from precaution…

@galinas, your onion challenge has got to be frustrating. I figure I’ve got about 40 years experience with gardening and mostly just have the leaf-tip damage with onion seedlings. A mushy “watersoaked” type damage that dries to brown might suggest bacterial problem when no fungal growth develops. It is interesting that your other seedlings are fine in this mix. If it were me, I would try a commercial seed starting mix with the onions and see if it solves your problem. I’ve gone to this after having problems with damping off and other issues with my home-made mixes. But my annual seed starting is limited enough that a few bags is not cost prohibitive and seems to give me more consistent results.

Thanks, yes, I already started new batch in pro-mix. - it is a commercial mix. I started mixing my own mix after I lost all my starters in miracle-grow potting soil. The thing is, I start my plants early in regular starting mix in small cells. But in 2 leaves stage I transplant them in half-gallon pots where they grow form March to May. That year they all died after transplanting… So I decided to mix it myself from that time on.

Do you know if there are any particular bacterial diseases that affect onions?

@galinas, regular miracle grow potting mix I’ve found to be a bit variable. Not sure if the fertilizer isn’t always well mixed, pH is off or what, but it isn’t really designed for seedlings. The common bacterial onion diseases I’m aware of would be soft rots typically affecting the bulb of more mature plants. But it might be plausible for infection of young seedlings based on your symptoms though I’m not familiar with it. Hopefully different potting mix does the trick!

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