Prairie Soils & Crops Journal Long-term Pesticide Free Production Study at Carman, MB (2000)

A long-term rotation was started in 2000 at the University of Manitoba to investigate the effects of Pesticide Free Production (PFP), a production system where in-crop herbicides were omitted from certain crops in rotation, on weed populations and crop performance in two crop rotations (flax-oat-canola-wheat and flax-oat-alfalfa-alfalfa). Over the long-term, weed seedbank populations were greater in rotations where in-crop herbicides were omitted, but significant yield reductions were only observed in some crops when omitting herbicides in both, the flax and oat crops. Over the 10 years, a crude economic analysis suggests that occasional in-crop herbicide omissions, particularly in competitive crops, may increase net revenues by saving the costs of herbicide while having no major impact on weed populations and crop grain yield