>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."


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