Features

• In a large weed population, a few plants that are inherently immune to a particular herbicide will infest an area after the herbicide kills susceptible plants. This selection process produces an herbicide-resistant weed population. If one type of weed continues to grow after others are eliminated, and if one type of herbicide has been used repeatedly, the weed is probably becoming resistant.
  
  

Time Frame

• A weed population can become resistant after four to 10 consecutive years of application of a particular herbicide. For example, according to an article published by the University of Missouri Cooperative Extension, goose grass was reported resistant to an herbicide containing dinitroaniline after 10 years of repeated use.
  
  

Solution

• Use alternative measures, such as soil cultivation, to control weeds. If you use herbicides, rotate crops and types of herbicides each year, so immune weeds do not become dominant.