Agronomy •  2021-06-02

Optimize the application timing of your pasture herbicides

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Corteva Agriscience™ Range & Pasture herbicides are effective tools in managing weeds, brush and trees in permanent grass pastures. Understanding how to optimize their application timing is important to ensure satisfactory results and to protect desirable species and the environment.

Identification of weeds, brush and trees

At first glance a pasture may look green and healthy, but upon closer inspection, you may find weeds that are robbing valuable forage from your pastures and profitable weight gain from your cattle. Left untreated, weeds can rob a pasture of up to 63 percent of forage yield, while invasive weeds can rapidly take over a pasture. Invasive plants are those that thrive and spread aggressively, to the extent that they are believed to cause damage to the environment. They have the ability to reduce the quality and quantity of forage by making it less accessible and/or attractive to grazing animals and by competing with desirable plants. Those are significant reasons to identify unwanted species and control them, ultimately protecting the long-term health and sustainability of your pastures.

Application timing of unwanted species

Herbicide applications should be done after the majority of the target weed populations have emerged and are actively growing, prior to flowering. The ideal timing for most weeds will generally be early June through mid-July with the exception of Canada thistle which enters its ideal timing in mid to late July when the majority of plants have emerged. When targeting shrubs such as buckbrush or wolf willow, ensure they are at full leaf expansion and have not developed a waxy cuticle on the leaf – ideal timing is typically June to early July. When targeting less than 12’ in height trees such as aspen and willow, ensure they are actively growing with no insect nor disease pressure and are at full leaf expansion – ideal timing is before August. Timing may vary from season to season due to environmental conditions that influence growth and plant staging. 

Ideal application timing of Range & Pasture herbicides

Restore™ II herbicide is an easy-to-use, broad spectrum product for the control of invasive broadleaf weeds such as scentless chamomile, tall buttercup and Canada thistle. Reclaim™ II herbicide delivers the most trusted extended control of broadleaf weeds and brush, such as silverberry (wolf-willow), Western snowberry (buckbrush) and wild rose. Grazon™ XC herbicide provides proven and effective extended control of a variety of broadleaf weeds and trees, such as aspen, birch and willow.

Proper application timing to a broad range of weeds may be challenging since emergence and growth stages may occur at different times throughout the season. Target your herbicide application when your most problematic weed is actively growing. For example, if your primary weed is absinth wormwood, Restore II application timing will likely be May 15 to June 15. If your main target is buckbrush, Reclaim II application timing will likely be June 1 to July 15. Shrub species will develop a waxy cuticle on the leaf surface resulting in reduced uptake and control later in the season. Finally, if you are looking to control Canada thistle, you need to wait long enough for the majority of the thistles to emerge before applying Grazon XC, likely July 1 to July 30. If environmental stresses such as severe drought or extended periods of heat are inhibiting growth, this may decrease product efficacy.

Corteva Agriscience Range & Pasture herbicides control weeds and root systems that are treated; if some weeds have not emerged at the time of application, these weeds will not have the same level of control as weeds that were fully emerged. Water volume is also an important component to ensure proper coverage of the target plant. Use a minimum of 20 gallons of water per acre for ground applications and 5 gallons of water per acre for aerial applications. Maximum one application per year for all treatments, refer to the product label for complete use directions.


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Author: Isabelle Thibout, Range & Pasture Product Manager at Corteva Agriscience