Yellow spots on leaves? Spreading :-(

[Yourmomm]

I've recently move my tomato seedlings into a glasshouse, and this has happened! I'd assumed it was water stress of some sort, so stopped watering from above and made sure there was no over or under watering, but the problem seems to be getting worse... Any ideas of what it is, and how to treat it? Are these seedlings save able? Thanks for your advice.

[applestar]

The first photo with large browned patches look like sunburn. In the glass house, it probably got more direct sunlight than it is used to, even though the glass does moderate the sun. It is better to acclimate plants slowly when moved out from Indoor/shady location by exposing them to only 30 minutes to 1 hr of direct sun at first, then gradually increasing, or by provided a lathe or sheer/lace/shade cloth cover.

The second one with tiny white marks looks to me like evidence of sucking insects — maybe whiteflies or (thrips? — I’m not familiar with them).

[Yourmomm]

Thank you! No there are no insects. I'm sure you're right about the sunburn, for both of them. I didn't know tomatoes got sunburnt.

If it is sunburn, how do I fix it, then? Will they recover naturally? (I'm assuming it's too late to acclimatise them now, as they've been out for more than a week).

[rainbowgardener]

The burned leaves will not recover, but new leaves that come out should be fine.

I agree with applestar that the bottom picture looks like damage from some sucking insect (but a severe case!). Thrips are nearly microscopic, can be a millimeter or two, but can be only half a millimeter (= 0.02 inch !) Try shaking your leaves over a piece of white paper and then look with a magnifying glass. Insecticidal soap spray is effective against thrips (as well as a number of other soft bodied insects). It is commercially available or can be made of certain types of household soap

[Yourmomm]

Thanks again... I will see what I can find, tomorrow, by way of soap spray, and spray the leaves as a precautionary measure...it has to be organic though, so any artificial, or man-made soap, doesn't sound ideal!

[rainbowgardener]

Soap, NOT detergent, is a natural organic product. Look for things that are pure soap like Dr. Brunner's, Murphy's oil soap, Ivory 99%pure (not Ivory detergent, they make both). Most of the things we use for dishes and laundry are detergent.

[Yourmomm]

Will do, thanks... I was doing some research last night about neem oil. Will post a separate forum question about it.