Farmers adopting no-tillage often cite adequate weed control as their biggest concern.
Weed species shifts Research studies conducted across western Canada have allowed comparison of 77 site-years of data to examine the impact of various cropping practices on weed populations. In years of low rainfall and high temperatures, species such as kochia and Russian thistle increased regardless of crop rotation or tillage. In situations where high rainfall was received in fall or early spring, winter annuals such as downy brome and flixweed and perennials such as dandelion and quackgrass increased in all cropping systems. Crop rotations with a high frequency of winter wheat had high populations of the winter annual weed downy brome while systems dominated by spring wheat had high numbers of summer annual weeds such as wild oat and green foxtail. Nevertheless, changing tillage practices can result in marked shifts in weed species over time that may pose problems for producers.