My spinach (Solanum nigrum) leaves are turning yellow and have attached couple of pictures. What could be the issue? Nitrogen deficiency? over watering ?
Thanks!

Hi!
I looked up your plant, as I have never heard it called spinach. It is not the spinach (Spinacea) that we all know from the grocery store.

But WIkipedia says you can eat the leaves of Solanum nigrum
https://en.wikipedia.org/wiki/...

I think I have seen this symptom of wild Solanum, but as they were wild for me, I did not try to treat them.

If you intended to grow 'grocery store' spinach, you've got the wrong plant, sorry.

Appears to be a bad case of spider mites, I suggest you remove and destroy the plants in order to keep the mites from transferring to other plants in your garden.

Thanks sallyg and gardenfish. Looks like it is severe manifestation of spider mites and universal DIY solution is neem oil or essential oil based. Let me try. Thanks.

Please don't call it spinach, it's not. Read the link Sally provided regarding toxicity.
And that is one bad case of spider mites. I too would destroy it. In fact, I pull any solanum that appear in my garden.