SCOTT SIMON, HOST: The World Cup is already here this summer for some grass-growing scientists at the University of Tennessee. They're trying to make 16 fields across Canada, Mexico and the U.S. into a - into the perfect expanse of green grass on which to play the beautiful game. John Sorochan is a professor of turfgrass science at University of Tennessee at Knoxville and in charge of designing and growing the grass fields for the World Cup. He joins us now from Knoxville.