DONALD G. McNEIL Jr. “Virus Ravages Cassava Plants in Africa” http://www.nytimes.com/2010/06/01/science/01cassava.html
温帯地方に住んでいる人には馴染みがないかもしれないが、キャッサヴァは旱魃に強いところから、熱帯地方では広く栽培されており、世界的に見ても稲、麦に次ぐ澱粉源（カロリー源）となっている；
上の記事によると、2004年以来、アフリカ大陸ではそれまでは沿海部にしか見られなかったbrown streakというウィルスが内陸部にも急速に蔓延し、キャッサヴァに大きな打撃を与えている。このウィルスに冒されたキャッサヴァは「豚も食わない（Even the pigs refuse this）」；
After rice and wheat, cassava is the world’s third-largest source of calories. Under many names, including manioc, tapioca and yuca, it is eaten by 800 million people in Africa, South America and Asia.
ただ、このウィルスがアフリカ以外のキャッサヴァ栽培地に拡がるかどうかについては、今のところ見通しは楽観的であるようだ；
That newcomer, brown streak, is now ravaging cassava crops in a great swath around Lake Victoria, threatening millions of East Africans who grow the tuber as their staple food.Although it has been seen on coastal farms for 70 years, a mutant version emerged in Africa’s interior in 2004, “and there has been explosive, pandemic-style spread since then,” said Claude M. Fauquet, director of cassava research at the Donald Danforth Plant Science Center in St. Louis. “The speed is just unprecedented, and the farmers are really desperate.”
キャッサヴァとタピオカが一瞬結びつかなかったというのは俺だけか。
Dr. Fauquet fears brown streak will cross the Congo Basin to Nigeria, the world’s biggest grower, because farmers sell cuttings to one another and border controls are nonexistent or can be evaded with bribes.He is optimistic it will not cross the ocean into Thailand, Brazil, Indonesia or China because there is no world trade in the cuttings and few direct flights to Asia or South America. (Whiteflies, which are thought to spread the virus, have been known to stow aboard planes.)
However, he noted, mosaic virus did spread to India from Africa somehow. And Dai Peters, the Cassava Initiative’s director, noted that a mealybug that damages Brazilian cassavas has leapfrogged the globe to infect Thai fields, too.
