State, federal and extension experts are encouraging Iowa farmers to stay vigilant in their efforts to control the spread of Palmer amaranth.

Farmers should be checking their soybean fields to make sure weed escapes presumed to be waterhemp aren’t actually Palmer amaranth infestations, said Bob Hartzler, a weed science professor and Palmer amaranth expert at Iowa State University.

The similarity between the two weeds will allow Palmer to go unnoticed until it’s too late to eradicate from a field unless people are always on high...