The Irish people were growing tons of crops besides potatoes, but the British landlords took everything besides the potatoes as cash crops/taxes, leaving them only the potatoes to actually eat. There was more than enough food to prevent those deaths, but the Irish people weren't allowed to eat it.

Do you not understand that it's a joke?

Obviously we all know the paper is talking about the microorganism, but since the real cause of the famine wasn't the microorganism but the British, it's funny to act like the paper is insulting the British rather than talking about the microorganism.

That's the only way I can interpret your comment in any coherent way, that the joke just went completely over your head.