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There are many different types of invasive plant species, often referred to as "weeds", that cause problems for farmers in Alberta. Some of the more important plant species include Canada thistle, chickweed, cleavers, flixweed, scentless chamomile, stinkweed, toadflax, narrow leaved hawk's beard and wild oats. Those are some strange names. These weeds can be highly competitive, particularly if they become established before the crop. Well established weeds compete with the crop for soil moisture and nutrients.

Ploughing used to be the main way of controlling pesky plant species on cropland in Alberta. However, changing land management practices have seen a trend toward less ploughing of the soil. With the availability of modern day herbicides, weed control in the agricultural sector has shifted dramatically towards chemicals combined with other control methods. A herbicide is a chemical that destroys plants. Your parents may use herbicides in your garden or flowerbeds to get rid of weeds.

In recent years, the number of herbicide-resistant weeds and the area they infest in western Canada has increased at an alarming rate. These weeds must have built up a tolerance to the herbicides over time. Much of Alberta's crop area is in the early stages of one type of resistance or another. The best methods to delay establishment of resistant weeds include regularly changing crops and herbicides, and using plant competition, mechanical methods, and other means to augment chemical control.