Yellow & brown ring on Den leaf

[NewBloom]

The discloration started about three days ago. The ring was a light green like Photo 3 and then deepened to brown in the center along with yellowing. The photos were taken Tuesday morning and by evening the color had gotten more intense.

As you can see, the top right leaf is starting to show the same problem. Last Thursday it got some sun exposure for twenty minutes. I don't think this is sunburn though.

What is this and what can I do?

[kmarch]

I think it is a sunburn. I'd remove the leaf with the big brown spot as it looks like it is dying off anyway. How is the other, upper leaf?

[NewBloom]

I hope it is only sunburn, K. I thought the results of sunburn would appear within a day. This leaf issue has been progressing over a few days.

The upper leaf still looks as it does in the picture. The discoloration is faint, however that's just how the other leaf started out too. I'm in the process of ordering a shade cloth and until it arrives I'm moving plants around.

[digitalgate]

sun burn took a few day to appear, bacteria rot appear in one day.