The Great Irish Famine (1845-1849) was caused by susceptibility of the potato to Phytophthora infestans. The wine industry in Europe was devastated by susceptibility to Phylloxera during the late 19th century. Each crop then had to be replaced by a new cultivar imported from another country that had used a different genetic variant that was not susceptible to the pathogen.
When I look at that field of virus contaminated cannas, I think that qualifies as a catastrophic monoculture crop failure as well. The picture originates from Keith Hayward's article on Canna virus. Unfortunately, we don't have anything that is immune to Canna virus at present. However, if that field had been rotated with another crop regularly, is it possible that it would not have occurred?
This brings the topic around to crop rotation. Crop rotation avoids a decrease in soil fertility, as growing the same crop repeatedly in the same place eventually depletes the soil of various nutrients, causing plant stress. Crop rotation is also used to control pests and diseases that can become established in the soil over time. Just adding chemical fertilizer does not avoid catastrophic crop failure.
There is no evidence to suggest that our major problem of viruses is transmitted through the soil, but the general rotation principles apply, and Cannas are a particularly hungry crop, quickly consuming whatever nutrients are present. It is actually an agricultural plant. Should we be thinking about rotating the locations in which we grow our Cannas?