Economics professor: Plant high-yield varieties to help fight wheat rust

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Philip Pardey, a professor of applied economics at the University of Minnesota, was a featured speaker at the recent International Wheat Conference in Sydney, Australia.

The focus of Pardey's presentation was wheat-rust disease research. Pardey said that even though there has been extensive research on the subject, wheat crops still fall victim to damaging stem, stripe and leaf rusts.

Pardey said the annual global investment in wheat-rust research should be $108 million a year. Most major wheat-rust eradication initiatives are only funded for set periods of time and target specific rust strains -- which Pardey does not think will work.

“It’s fallacious to think that we can ‘solve the stem-rust problem’ through funding because the actual solution sows the seeds of its own destruction,” Pardey said.

Pardey recently conducted a study that showed global losses from all three major rust strains average at least 15.04 million tons (552.8 million bushels) per year -- an average annual loss of about $2.9 billion.

“The nature of the intervention is that the very seeds of success of wheat breeders sows their own destruction,” Pardey said. “A co-evolutionary pressure is developed where rust has every incentive to survive, so when fungicides are used or the biology of the plants is altered to resist those fungi, it forces evolutionary pressure on the fungi to evolve around that resistance.”

Almost the entire global wheat crop is at risk of infection from wheat rusts, Pardey said.

“In 1935, the United States lost a fifth of the crop to rust; last year, they lost less than half a percent,” Pardey said.

Pardey has developed a framework to characterize the likely nature of losses over the next century, then he conducted a Monte Carlo simulation to evaluate risk impact under all possible outcomes of a given scenario to determine a loss-average estimate.

“If wheat breeders are successful in getting modern varieties onto all the wheat areas around the world, there is additional value because they’re at a higher yield level, when the disease pulls the yields down,” Pardey said. “High-yield varieties make the value of the rust avoidance go up as the yield goes up. You’ve got a virtuous cycle. The rust resistance becomes more valuable the more extensive the higher yielding varieties are spread. An investment of $108 million a year just allows us to keep up with it – we’re running fast to stand still."

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