WEST LAFAYETTE, Ind. (AP) _ A fast-spreading weed that can grow up to 7 feet tall and clog up cropland has moved beyond northwestern Indiana and spread into 17 of the state's counties.
 
  Purdue Extension weed scientist Bill Johnson says Palmer amaranth has been found across northern Indiana and in parts of east-central, western and far southwestern Indiana.
 
  He says that the plant “is potentially the most aggressive agronomic weed Indiana producers'' have ever dealt with. Johnson says it must be managed with an aggressive control program.
 
  Palmer amaranth can grow up to 2 inches a day in summer heat and it's typically resistant to herbicides used in corn and soybean fields.
 
  Each Palmer amaranth plant can produce up to 500,000 seeds.