The Botany of Desire: A Plant's-Eye View of the World

by Michael Pollan

I asked Forsyth to walk me through a season’s regimen, the state of the art in the control of a potato field. Typically it begins early in the spring with a soil fumigant; to control nematodes and certain diseases in the soil, potato farmers douse their fields before planting with a chemical toxic enough to kill every trace of microbial life in the soil. Next Forsyth puts down an herbicide—Lexan, Sencor, or Eptam—to “clean” his field of all weeds. Then, at planting, a systemic insecticide—such as Thimet—is applied to the soil. This will be absorbed by the young seedlings and kill any insect that eats their leaves for several weeks. When the potato seedlings are six inches tall, a second herbicide is sprayed on the field to control weeds. Dryland farmers like Forsyth farm in the vast circles I’d seen from the sky; each circle, defined by the radius of the irrigation pivot, typically covers an area of 135 acres. Pesticides and fertilizer are simply added to the irrigation system, which on Forsyth’s farm draws water from (and returns it to) the nearby Snake River. Along with their ration of water, Forsyth’s potatoes receive ten weekly sprayings of chemical fertilizer. Just before the rows close—when the leaves of one row of plants meet those of the next—he begins spraying Bravo, a fungicide, to control late blight, the same fungus that caused the Irish potato famine and is once again today the potato grower’s most worrisome threat. A single spore can infect a field overnight,...