Page 208 - Encyclopedia Of World History

558 berkshire encyclopedia of world history

Dobyns, H. (1983). Their numbers become thinned. Knoxville: University Diseases of the
of Tennessee Press. Staple Grasses
Gottfried, R. (1983). The Black Death: Natural and human disaster in
medieval Europe. London: Robert Hale. Wheat Rust
Martin, C. (1978). Keepers of the game: Indian-animal relationships and Wheat rust is among the oldest plant diseases. Some
the fur trade. Berkeley: University of California Press.
Sale, K. (1992). The conquest of paradise. New York: Alfred Knopf. scholars believe that a 3,800-year-old passage in Genesis
records an outbreak of rust in the Levant that caused
famine so severe it forced the Hebrews to migrate to
Egypt, the granary of the ancient Mediterranean world. If
these scholars are right, this text is the earliest written
Diseases, Plant account of a plant disease.

Only in the fourth century BCE did Theophrastus, a
reliterate peoples as well as some literate peoples Greek botanist and pupil of Aristotle, coin the term rust
Pbelieved that spirits cause disease. Greek physicians for this disease because of its reddish hue on the leaves
dismissed this notion and instead insisted that disease and stem of wheat plants.Theophrastus wrote that wheat
had physical rather than supernatural causes. In the fifth planted in valleys and other low ground suffered from
century BCE, the Greek physician Hippocrates taught rust more often and more acutely than wheat planted on
that an imbalance of fluids causes disease in humans, a high ground though he could not explain this fact.
claim that left inscrutable the cause of disease in plants. That insight came to the Romans.As early as 700 BCE,
In the nineteenth century, the German botanist Anton de they identified the reddish hue on wheat plants as the
Bary, the German bacteriologist Robert Koch, and the mark of rust.At that time they began to worship Robigus.
French chemist Louis Pasteur swept aside the ideas of Historians identify Robigus as the god of rust, a fair state-
Hippocrates De Bary, working with the potato, and Pas- ment so long as one remembers the Greek rather than
teur and Koch, working with cattle, demonstrated that Roman origin of the term rust. The idea that a god
pathogens (parasitic microbes) cause disease. The germ unleashed rust on the Romans underscores their belief
theory of disease is the foundation of modern medicine. that rust had a supernatural cause.Trade with the Greek
The focus on human diseases should not deflect atten- city-states led the Romans to abandon a supernatural
tion from plant diseases. Despite a perception to the con- explanation of plant diseases. In the first century BCE, the
trary, plants suffer from more diseases than humans do naturalist Pliny the Elder made the crucial link between
and for an obvious reason. Plants colonized the land 410 moisture and the onset and spread of rust, writing that
million years ago, whereas modern humans made their rust afflicted wheat grown in areas where fog and dew
appearance only 130,000 years ago.The pathogens that were common in morning and evening. Pliny’s insight
attack plants have had some 400 million more years to into the role of water in spreading rust was prescient
evolve new types by mutation than those that attack because rust, like all fungal diseases, spreads in wet envi-
humans. ronments. The rust fungus needs water to produce the
Plant diseases have shaped history. Even as nomadic millions of spores that are the next generation of fungi.
foragers, humans depended on plants for sustenance.The Two centuries later, the agricultural writer Columella
rise of agriculture in western Asia some 10,000 years ago warned farmers against staking their livelihood on wheat.
and its spread throughout the world have wedded the The only protection against rust was to grow a diversity
destiny of humans to that of crops (domesticated plants). of crops. Columella recommended cultivation of the
Whatever has threatened crops has threatened the health chickpeas and lentils because of their immunity to rust.
and survival of humans. Columella had reason to worry: The first three cen-