Weeds are defined as "a plant out of place." Plants can be weeds when found where they compete with valuable crop and forage plants and threaten native plant species. Many weed species on the prairies are plants that have been introduced to North America from other places in the world.
In the management of unwanted pests such as weeds, good integrated pest management techniques include using various methods of control:
- Mechanical control, with methods such as hand picking weeds, is ideal when the weed population first invades an area;
- Chemical controls work well for some weeds and in certain situations (cropland), however are often non-selective on non-target plants. When weeds are an issue in sensitive areas, chemical controls cannot be use; and
- Biological controls offer another method of weed management that can be used alone or in conjunction with chemical and mechanical methods to manage invasive weed species.