The pathogen affected all of Europe but only Ireland suffered a famine. So, blaming the pathogen on its own is not convincing. British policy did play a central

The pathogen affected all of Europe but only Ireland suffered a famine. So, blaming the pathogen on its own is not convincing. British policy did play a central role. As a matter of law, the Irish were not allowed to own land. They could only rent a limited amount from landowners -- 0.5 acres at most, if my memory serves. And the only culture with a sufficient yield per unit of surface that the Irish could both make rent and feed themselves was the potato. The rest of the land served to produce other crops for the benefit of British landowners. As a result, the island of Ireland was in fact producing enough food to feed its population through the Famine. It was just exported to Britain instead.