THOSE WILY WEEDS | POST-HARVEST WEED CONTROL
Post-Harvest Weed Control “Cut thistles in May, they’ll grow again some day. Cut thistles in June, that will be too soon. Cut thistles in July, they’ll lay down and die.”
Tammy Jones B.Sc., P.Ag Tammy Jones completed her B.Sc. in crop protection at the University of Manitoba. She has more than 15 years of experience in the crops industry in Manitoba and Alberta, with a focus on agronomy. Tammy lives near Carman, Man., and spends her time scouting for weeds and working with cattle at the family farm in Napinka.
30
This piece of practical advice, or perhaps it is folklore, was part of a conversation with Mike Cowbrough, weed specialist with the Ontario Ministry of Agriculture, Food and Rural Affairs regarding tough-to-control weeds. The saying highlights the importance of weed biology in determining the most effective timing for weed control efforts. Spring weed control is especially effective for annual weeds and protecting crop yields. Pre-harvest weed control can be a good opportunity for optimizing harvest efficiency by reducing green plant material. But limitations on suitable crops, suitable herbicides, and issues such as wheel tracks in the field, complicate and possibly reduce the effectiveness of the pre-harvest options. There is a strong argument to be made for post-harvest weed control even though it too has challenges. Post-harvest timing can help control perennial weeds, minimize the impact of annuals’ re-growth, and address any newly emerged winter annuals. It’s also a great tool for optimizing weed control when the next crop has limited in-crop herbicide options. The main challenge for post-harvest weed control, is completing harvest before winter sets in. There are years where harvest doesn’t end until the next spring, but in years where there is an open fall and the opportunity, here are reasons to consider post-harvest weed control:
