Q: How do you get rid of Johnson weed? 

A: It’s tough! Johnsongrass, Sorghum halepense, was introduced from the Mediterranean as a pasture grass. But farmers soon found that this tall, aggressive grass, while favored by cattle, was very difficult to keep in bounds. Your only options are either to dig it out or spray with glyphosate whenever you see it. By consistently eliminating the leaves, the roots will eventually starve to death.