Panhandle Perspectives - October 10, 2017

Have Plant Diseases Influenced Food and Human Eating Patterns?

Robert M. Harveson, Extension Plant Pathologist, Panhandle R&E Center, Scottsbluff

Author’s note:  This is the third article in a new series involving examples of how plant diseases have impacted social and world history. 

Historians of plant pathology have studied the effects of plant diseases on human society and readily documented specific examples of how they have sometimes influenced or changed world history. I have recently written articles on the fungal disease, ergot and its presumed effects on affecting historical events.

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Bob Harveson

However, have you ever wondered how the cuisine of certain cultures or geographic regions originated? This article will focus on that topic, describing several historically famous diseases and how they have driven or modified the eating habits of large groups of people.

James Horsfall was a very influential plant pathologist best known for the discovery of and early work with organic, sulfur-based fungicides such as Nabam and Zineb. He also was recognized as an enthusiast and consummate writer and documenter of plant pathology history. Examples of how he maintained that certain diseases changed human eating habits are included below.

Wheat Rust in the New World

When the English immigrants arrived in North America in the early 17th century, they settled primarily in two locations – New England and Virginia. Horsfall suggested that it was also logical to assume that they both brought wheat with them from Europe. He also suggested that it was highly likely that wheat rust traveled with them to their new homes, yet operated differently in the two places where they established residence.

Wheat rust is favored by a warm and wet climate. Horsfall theorized that the colonists in Virginia likely experienced greater rust problems than the New Englanders as a result of warmer conditions. It also presumed that the difficulty in productively growing wheat by Virginia colonists caused a shift to corn, rather than the preferred wheat bread of their English ancestors for a carbohydrate source. This concept is still observed today with the consumption of cornbread, grits or hominy being more common in the southern U.S. than in the North.

Horsfall further asserted that as Americans moved westward, they continued to take wheat farming with them into the Great Plains. The southern plains (Texas and Oklahoma) were warm enough for rust to develop; however, the environmental conditions of these areas were often more arid than the humid eastern seaboard and southeast. Therefore, wheat production suffered less damage as a result of the unfavorable climate for disease compared with the eastern United States.

Cereal Consumption Habits in Europe

A similar pattern of cereal production and consumption was seen in Europe to that of America.  Dietary habits throughout the continent were strongly influenced by contrasting environments and resulting plant diseases. The weather in England was wet enough to effectively grow wheat, but was too cool in general for wheat rust to be problematic to production.  Thus it became the grain of choice to the English who tend to favor wheat bread.

The weather in Italy is warm enough for growing wheat, but generally too dry in summers for optimal rust development, like that of the southern plains of the United States; and the Italians are well known for using wheat for both bread and pasta.

Wheat grows less effectively throughout central Europe (France, Switzerland, and Germany). The climate there is similar to the wet and warm growing seasons in Virginia unlike that of England. Rust on wheat was severe in this region. Thus the Germans in particular became consumers of rye for their bread, rather than the corn of the Virginia colonists. Rye is not as susceptible to rust as is wheat. As a result of widespread cultivation of rye, ergot became hugely problematic, causing human misery and suffering throughout central Europe for centuries. 

Ergot never posed a serious problem in Britain or the Mediterranean due to the fortunate circumstances influencing the less favorable environmental conditions.

After potatoes were introduced, the peasant farmers rapidly discovered that this crop would provide more food per acre than either wheat or rye. As potatoes slowly replaced these cereals as a staple food in central Europe in the 18th century, the incidence of ergot also declined noticeably. However, the immense dependence upon the potato for sustenance that was created in Europe, particularly in Ireland, also initiated another problem in the 1840s – the Irish potato famine. But that is another story for another day.

This article is based on material from these sources:

Horsfall, J. G.  1956.  The fight with the fungi or the rusts and rots that rob us, the blasts and the blights that beset us.  Am. J. Bot. 43: 532-536.

Horsfall, J. G., and Cowling, E. B.  1978.  Some epidemics man has known.  Pages 17-32 in: Plant disease, an advanced treatise, Volume II, how disease develops in populations.  J. G. Horsfall and E. B. Cowling, eds.  Academic Press, 436 pp.