Rhubarb Disease - and possible soil contamination?

[westcoast_chicka]

Hello,

So I live on Vancouver Island in Canada. My neighbour recently gave me a rhubarb plant this spring that consisted of a softball sized root clump and a few small stems - it was quite healthy and literally came from "the other side of the fence." He told me it was quite hardy and I could plant anywhere - the sandy soil in our area would be fine. I had to put it in a pot for now since my garden is still in the works.

Heres my problem - a little less than a week later it started to wilt and the leaves because discoloured - I snipped the dead stems and watered as I am new to this and didnt know what else to do. Its now beel two weeks and the remaining leaves have holes in them surrounded by brown discolouartion. The stems have streaks from brown as well and look like they are rotting. The holes are quite large on the bigger leaves (around and inch) But there is still a couple healthyish stems left.

I am wondering if anyone knows what may have caused this problem? My main concern is if it was fungus, could it have come from contaminated soil in my garden??

I sprayed whats left of the plan with a neem oil solution - should I even attempt to salvage whats left of the plant or just destroy it?

Is my soil contaminated or is it just bad luck?

Thanks in advance,