What's going on here?

[Mark]

Hello all, I have these seedlings and they seem to have some sort of something going on. I think this is spider mite damage? The plants seem to be growing out of it, but want to have this solved before the winter comes. I will need to bring these inside since they are still seedling. I have been spraying with neem oil once a week. Could this have been some sort of sun burn??


Thanks!
Mark

[jfabiao]

I've read reports of bad scarring caused by the application of neem oil on plants exposed to the sun. The plants on the left look in fact to be growing out of a RSM infestation, so the neem oil spraying is a good measure, but you may want to keep them out of direct sunlight.

[george76904]

Neem oil and sun do not mix. In fact most insecticides and fungicides have a phototoxic affect when applied to cacti in the sun. If you need to apple it wait until the evening else you risk burning the plants. So to sum it up I would say yes the neem oil did produce the sun burn/ scarring that you are seeing on your little seedlings. However give them a few years and you wont even be able to tell!
hope this helps,
Will

[iann]

Any oil (or soap) plus sun is dangerous, almost guaranteed to burn in strong sun. Protect the plants for at least a day or two.

Other insecticides *might* cause problems but most of the modern ones are reasonably safe. The surfactants in them are probably more dangerous than the poison itself.

There still could have been pest damage. It often seems to appear as if by magic when you spray, although it was actually already there. Perhaps there is an increased burning affect on the already-dead cells, making them dry out and scar over.

[Mark]

Interesting. I am trying to remember how they looked before I sprayed them. I used to spray the plants in the morning, which could be how they scared. I do have them under a bench with shade cloth. I will try to spray in the afternoon.

Do you think the plants are better now? OR should I continue spraying?

Thank you all!

Mark