Fungal? Orange Yellow leaves

[Guavatone]

I gave a foliar feeding of Kellogg Fish/kelp concentrate Monday or Tuesday and thought I was getting a slight burn even though I did it at night. out of 15-18 plants 12 have healthy thick stems and the others have either thin stems or thin foliage. A friend told me this is fungal. I have Serenade and just sprayed with copper.

I'm scared bc todays rain into night seems to be spreading something to some of the healthy plants.

Please help.

These pictures are from today. The last one is just to show a healthier plant with just a few yellow leaves, and an overall view of the garden.

Thanks in Advance
-Charlie