By Cassandra Garrison TAPACHULA, Mexico (Reuters) -On a scorching afternoon in the rural heartland outside Mexico's southern city of Tapachula near the Guatemala border, rancher Julio Herrera calls his herd back from an afternoon of grazing.

Gov. Greg Abbott was joined by U.S. Secretary of Agriculture Brooke Rollins at the Texas Capitol where Rollins announced the federal government’s plan to spend up to $850 million to prevent the New World screwworm’s arrival in the United States.