What happened on the potato supply chain that caused a fry shortage in Japan and a ban on Canadian spuds

In the latest agriculture supply chain snafu, a shortage of North American potatoes in Japan is causing the rationing of fast-food fries. There are also disruptions in Kenya and South Africa where potato chip making has been stymied. While there is still copious trade in potatoes going on around the world, backups at ports, unseasonable weather, and an unexpected fungus, have made certain potato varieties hard to come by for the businesses that rely on them.