Cereals, Herbicide resistance, Weed control diversity
The US Great Plains comprise the major cereal producing states in the country. In the US, wheat (winter and spring wheat) was grown in 45 million acres in 2014, with a total production of 55 M metric tons. Wheat after chemical fallow (W-F) dominates > 90% of the dryland cropping systems of the Northern Great Plains of the US, where soil moisture (< 300 mm of average annual precipitation) is often the limiting factor for continuous cropping. In the Central Great Plains of the US, wheat–corn/grain sorghum–fallow (W-C/G-F) is a common dryland rotation. An over-reliance on herbicides for weed control in these no-till cropping systems has resulted in weed shifts and escalated cases of resistance evolution in weed populations to single or multiple site-of-action herbicides. Early detection, increased awareness of socio-economic implications of herbicide-resistant weeds, and adoption of diversified weed control tactics would mitigate the further evolution of multiple herbicide-resistant weed biotypes in cereal production systems.