Time to evaluate the effectiveness of your weed management program

The ability to control weeds is getting tougher and more costly every year. Whether the challenges involve a lack of registered herbicides for a specific crop, herbicide resistant weeds, or herbicides that are lost due to re-evaluation decisions by Health Canada's Pest Management Regulatory Agency, agriculture is challenged and will continue to be challenged. It is time to pay attention to the weed species that are present in each individual field on your farms and think about how you will manage weeds next year and in the years to come. This will require multiple or integrated weed management (IWM) approaches. This will not be simple, it will require more management and more evaluation; however, it must be done to ensure the economic sustainability of agriculture.

The best time to evaluate the effectiveness of your weed management program is at harvest. This evaluation should be the beginning of your 2014 weed management plan. Evaluation is the most critical component of IWM. Make notes of not just what weeds are present, but also their location and numbers within each individual field. This information will not only help your long term weed management plans, but will also help you decide whether or not you need to plant a cover crop or apply a herbicide this fall.

Weeds might escape management for several reasons:

  • selecting herbicides with low to marginal activity on the weeds present,
  • the weeds that are present are resistant to the herbicide that is applied, and;
  • environmental conditions. For example, rain at the wrong time after an herbicide application or drought stress which thickens the weeds cuticles preventing herbicides from being taken up by the plant.

Rating the effectiveness of an IWM program at harvest allows for easy identification of the weed species present and helps to determine which weeds are producing seed and are contributing to the weed seed bank. Secondly, rating at harvest will help determine which weed species are having the highest impact on crop yield. This should help prioritize which weed species need to be targeted and help prepare for potential future weed problems. Continuing to remain watchful of your weed problems will help prevent future weed escapes and yield loss.

Weed scouting at harvest as part of an IWM plan needs to be an ongoing process to remain proactive in your weed control efforts. Weed resistance is a growing problem and will be an on-going challenge for all future agriculture generations. Regardless of where a farm is located or what weed control products are used, a single herbicide mode-of-action is simply no longer adequate to protect yields and long-term profitability.



For more information:
Toll Free: 1-877-424-1300
E-mail: ag.info.omafra@ontario.ca