Roughly 90 percent of the world’s wheat varieties are defenseless against a virulent, fast-moving strain of stem rust fungus that is ravaging crops in parts of Africa, drifting into the Middle East and could soon threaten the breadbaskets of India and Pakistan.

Scientists worry that one billion people in Asia and Africa alone could be left without their primary food source – a modern-day version of the Irish potato famine from more than 150 years ago. Except this time, it’s global problem. An estimated $1 billion worth of wheat is at risk in the U.S., too.

A key weapon in fighting the disease is crop diversity. Plant breeders are right now reaching deep into the world’s major wheat collections, looking for traits that will allow them to develop new varieties genetically endowed to resist an attack from the spreading stem rust strain. The importance of crop diversity to combating stem rust has highlighted a long-standing problem: the growing lack of diversity in agricultural production today.

An eye-opening article in the July issue of National Geographic notes that the world has lost more than half of its food varieties in just the past century. In the U.S., an estimated 90 percent of historic fruit and vegetable varieties have vanished. China’s wheat varieties have seen similar losses. According to the article, such a dramatic “erosion in the genetic diversity of the foods we eat” is focusing new attention on “seed banks” that can provide a bulwark against extinction.

The article highlights the work of the Global Crop Diversity Trust. The Trust is committed to sustaining the world’s seed banks, whose collections are threatened by forces as dramatic as warfare and as mundane as poorly maintained refrigeration systems.

The Trust also operates the Svalbard Global Seed Vault in Norway, a fail-safe storage facility located deep inside a mountain on a remote Arctic island. This Noah’s Ark for food security aims to provide a back-up copy for every crop variety on the planet. It already holds more than 600,000 samples and is the single most diverse crop collection maintained anywhere in the world.

Given the many threats facing agriculture production today, seed banks form a critical line of defense.

“If disease or future climate change decimates one of the handful of plants and animals we’ve come to depend on to feed our growing planet,” National Geographic’s Charles Siebert writes, “we might desperately need one of those varieties we’ve let go extinct.”

Burness has worked with the Trust to spotlight the importance of the Vault — and the broader issue of crop diversity — culminating in its being named one of the 50 best inventions in 2008 by Time. (See our case study on our work with the Trust for more information.)

We also work with the Durable Rust Resistance in Wheat Project, a collaborative effort begun in April 2008 by 17 research institutions around the world, led by Cornell University. (wheatrust.cornell.edu)