They are here. They are ugly. And they are not going away.But farmers, you can still take control of waterhemp and its evil cousin Palmer amaranth, even in an era of herbicide resistance.

"The pace of resistance is accelerating, and glyphosate is no longer providing adequate weed control," said Bob Hartzler, an Iowa State University Extension weed specialist and agronomy professor. "When you’re fighting tough weeds today, you must emphasize a good pre-emerge herbicide program."

No longer can the focus be on a post-emerge program only. "Thinking you can catch tough weeds with a post program isn’t realistic," Hartzler said. "Timing is critical in weed control, and pre-emergence herbicides provide much greater flexibility."

Get them when they are small

The stakes are high. If...