By Sarah Sommerfeld, Regional Forage Specialist
Saskatchewan Ministry of Agriculture
Adoption of weed management strategies for forage stands can be a valuable tool. Weeds often associated with forage stands are perennial and hard to control plants, such as Canada thistle, foxtail barley, dandelion, leafy spurge, absinthe wormwood, and common tansy. As weed infestations increase in size and severity, the cost of control increases and the production of desirable plants declines. A weed management plan begins with field scouting and identification.
Scouting for weeds in forage stands should occur regularly. Scouting helps to determine if undesirable plants are present. Scouting also identifies conditions which favour development of a weed infestation. Poor plant competition from desirable species, bare soil or any other type of soil disturbance can lead to a weed problem. If these conditions are present, the next step is to determine the cause.
Look at the grazing management plan for the field; is there too much grazing pressure on the desirable forage plants? If there is bare soil, is it caused by overgrazing or poor forage adaptation? Have weed seeds been introduced to the area by feeding contaminated hay or unattended, neighbouring weed problems?
A weed problem will always have a cause. Effective long term weed control requires identification of the weed itself, and also the cause of the problem. To implement an effective weed management strategy, action must be taken to ensure the cause of the problem is addressed.
Scouting for new weeds is best done when they are easiest to identify, often in the month of June, prior to seed set. Correct identification of the weed is necessary to select the most effective control method. Consult with an agrologist or local weed inspector for assistance in weed identification or to discuss the best control method. When considering a control method be aware of the environment surrounding the problem area. For example, applying the herbicide picloram which has long term residual soil activity and high water solubility is not permitted near open water, wetlands or on soils with shallow aquifers.
Monitoring the area for effective control following treatment is important. If adequate control has not been achieved, an alternative control measure should be undertaken. Reasons for a lack of effective control should be determined and corrected for future reference.
For more information on scouting for weeds in forage stands, contact the Regional Forage Specialist at 306-867-5559 or the Agriculture Knowledge Centre at 1-866-457-2377.