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>Scientists Fight Global Fungus > >October 22, 2000 > > By TRACI CARL, Associated Press Writer > > TOLUCA, Mexico (AP) - The fungus that caused the Irish Potato Famine >is back. > The disease that shrivels potato crops has developed into more >aggressive strains that are spreading around the globe. Now >scientists on two continents are fighting >back by homing in on where the fungus apparently started. > Ground zero is Toluca, an industrial town just outside Mexico City >tucked into the > lush mountain valleys surrounding the nation's capital. Scientists >are growing five > acres of potatoes of every variety imaginable, trying to develop ones >resistant to the fungus behind the Irish famine, which killed 1 million >people and forced a mass migration to the United States in the >mid-1800s. > Tighter global ties have helped the fungus strengthen its hold, aided >by the spread of disease in goods shipped to far-flung markets. > The fungus attacks the short, leafy potato plant and sometimes the >tubers themselves, devastating one of the world's most important food >staples. It can even appear after harvest in warehouses. > Toluca is believed to be where the disease began, and it is still >considered one of the toughest places to grow potatoes because the >fungus - called potato late blight - thrives in the region's cool, wet >climate. > The same mountain climate is also perfect for growing potatoes, which >is exactly what U.S. scientist John Niederhauser tried to do when he >arrived nearly half a century ago to help boost Mexico's crop. Yet he >confirmed what local residents said was true: potato plants >mysteriously died here, prompting him to work to find ways to fight >late blight. > Niederhauser, who won the World Food Prize in 1990 for his work, >helped Mexico increase its potato production sixfold from 1950 to 1980 >by developing resistant varieties. During the same period, per capita >consumption of potatoes more than tripled. > Today, resistant varieties make up 30 percent of Mexico's 185,300 >potato acres. > The fungus still naturally flourishes in the country's mountain >valleys, making it the perfect place to test new varieties. > Scientists don't even have to infect the plants: If a potato plant >can grow here, it can grow anywhere. > Two programs - one based in Mexico, the other at Cornell University >in Ithaca, N.Y.,- are working to develop resistant potatoes. Under the >partnership, scientists from Russia, Poland and the United States breed >new potato varieties and send them to Mexico to be tested. > Each day scientists check the test plants, walking through the rows >and noting whether they are thriving or giving into the fungus, >shriveling up as if they had been burned. > Although some resistant varieties have been developed by breeding >wild species that naturally defend against the fungus with conventional >potatoes, all have major problems that prevent them from being widely >used. Some aren't right for making potato chips or french fries, while >others need too much water or take too long to mature. > Scientists believe a resistant variety that will be widely popular >with farmers and consumers may be up to 10 years away. > Until then, larger growers are spraying more and more fungicide to >try to control the problem. > One or two applications of the fungicide metalaxyl each growing >season used to protect crops all over the world. "It basically solved >the late blight problem," said Phil Nolte, a plant pathologist at the >University of Idaho. > With the creation of metalaxyl two decades ago, scientists focused >less on developing potato varieties resistant to late blight, Nolte >said. But in the past decade, scientists began noticing a more >aggressive strain that isn't halted by metalaxyl. > To keep the disease from devastating a field, farmers must spray >fungicide repeatedly - up to 12 times each season in the United States, >which can add $200 an acre to production costs. > The new strain has spread to almost every corner of the globe. > The fungus travels by air and can destroy a field in days. > It showed up in the United States in 1992 in New York and Maine, >reaching as far west as Idaho by 1997. The strain, likely among many >that have always thrived in Mexico, also can be found in Europe and >Asia - particularly Russia - and Africa. > The need to spray more and more fungicide is making potato farming >around the world less profitable, and it is harder on the environment. > "It's right on the edge of putting farmers right out of the >business," said John Helgeson, a plant researcher in Madison, Wis., for >the U.S. Department of Agriculture. > The disease appears to be a bigger threat in developing countries, >where small farmers dominate and money for combating it is tight, said >Hector Lozoya, technical director of Mexico's program. > The fungus is particularly devastating in Russia, where many people >grow potatoes in small garden plots and can't afford to spray >fungicide. > "Potatoes are a sustaining food crop, the second bread for many parts >of Russia," said W. Ronnie Coffman, chairman of the Cornell >University-based program. "A severe late blight problem could harm >millions of people and possibly destabilize the > region." %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%