I have a meyer lemon growing in a container. This morning i noticed that some of the roots were exposed so I brushed some soil from the sides of the pot to cover the roots. Upon doing so I exposed a yellow like substance. It was bright in colour (canary yellow, really vibrant) and looked almost wet and slimey. It was about an inch under the top soil, I had not seen any of it until i disturbed the topsoil. On one of the larger pieces of mulch, it appeared to have creeped and crawled its way thru the soil, and had what looked like raised veins. My tree appears to be fine, so i am not sure if i should re-pot it in fresh mulch. Or should i try and remove as much of the contaminated soil as possible? Or leave it alone?
I suggest you post pictures, that sounds kind of spooky. I think you should remove it, that's usually the safest option.
