The strategy in the battle against herbicide resistant weeds is more important than ever — use herbicides with multiple modes of action and make timely applications, Iowa State University Extension field agronomists said last week at a field day in Story County.

The herbicide resistance de­­monstration plot tested dozens of herbicide and timing combinations to see which management strategies provided the best control. Overall, the best results were seen in plots where a pre-emergence herbicide was applied, followed by a timely...