want opinions on what this is...

[BigVanVader]

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This just appeared on quite a few of my seedlings in the past 2 days.
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Also getting odd leaf curl from the Wapsipinicon variety.
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Closer view. This is the only variety affected.

Any help appreciated!

[efisakov]

If its aphids, leafs underneath would be sticky. Spider mites are working slower than 2 days. It looks more like a sun exposer with some chemicals.

[JamesL]

Same potting mix on all plants and only one variety showing the leaf curl?
Can you post a close up of the white on the leaves? Can't zoom in to see it real well.

[PhilSeneca]

It looks like a combination of sunburn and edema to me. the curl is definitely edema. if you water less, and more frequently, it will reduce the edema, but mostly just water less. the new leaves will be unaffected by the sunburn and edema.

[BigVanVader]

I was out of town for 3 days and they got no water. When I came back many of them were wilted badly and so i watered them good. I think these may just be signs of that stress. I have them all in my hoop house, can they get sunburned under plastic? All the plants on the lower shelves (more shade) still look great so maybe too much sun exposure during the hardening off?

Oh and I checked them with a magnifying glass and no signs of insects.

[joseph]

Originally Posted by BigVanVader

can they get sunburned under plastic? All the plants on the lower shelves (more shade) still look great so maybe too much sun exposure during the hardening off?

I've never had tomatoes get sunburned under plastic if it was 6 mil or thicker. I've had them cook if it wasn't properly ventilated. My hardening off strategy is to take tomatoes directly from the fluorescent lit basement to outdoors all day long in full sun, with a canopy of plastic to protect from UV light. I leave the sides of the canopy open so that they don't overheat.

[PhilSeneca]

heat can also be a factor. chloroplasts start to blow over 109 F. if they were near the top of the plastic shelter it may have been too hot.

heavy watering after dry conditions can easily cause edema. with the most water retaining potting mixes, edema can happen very easily. i prefer a mixture of compost, clay and perlite with minimal coco or peat. too much inactive humus for water retention will malnourish the plants while absorbing too much water before it has a chance to percolate through the container.

[BigVanVader]

I use Metro-Mix 360 for all my plants which is peat based. It sounds like they just got to stressed and resuming normal watering/feeding schedule should remedy my issues. Luckily I sold most of my plants this past week and the ones ready to sell are still looking fine. These were for my sister in Asheville NC and so I have a month to get them back full health.

[garden381]

Originally Posted by joseph

I've never had tomatoes get sunburned under plastic if it was 6 mil or thicker. I've had them cook if it wasn't properly ventilated. My hardening off strategy is to take tomatoes directly from the fluorescent lit basement to outdoors all day long in full sun, with a canopy of plastic to protect from UV light. I leave the sides of the canopy open so that they don't overheat.

So, i have black crim, purple russian, San Marzano and mountain strains all flourishing very well under 10 mil plastic in zone 8A, Jacksonville florida. it's been 85-92 with evenings in the 70's and everything is happy. I do keep the ends open but a very important thing is I go to the dollar store and get a RED PLASTIC TABLECLOTH. I cut this so it fits around the bases of the plants and then i make watering /ventilation holes. This red plastic allows the light to be reflected into the centers of the plants to have a blue wavelength which is very good for tomato plants.
As far as my seedlings, I start on top of peat moss ground to a powder then as soon as they sprout, i put them outside on my patio.here they remain,exposed to the elements except fpr pounding rain. i do loose plants but the remaining plants are beyond strong and, planted on their side when transplant time comes, produces a plant exceptional in strength and production. i use lambert garden soil (bagged)amended with composted cow manure.
i do not fertilize...ever...no compost, no anything and i have near perfect p'duction and big tomatos till late fall.
remember, all plants are from nature and there the strongest survive and thrive. making these plants strong is easy. DO NOT BABY THEM. no hot houses ect. it does work. my sprouts this year were put outside when the temps were 39-45 degrees!. Most lived,some died. the living are doing incredible!! Pictures to post following this reply