Management of horse pastures was discussed in last week’s eUpdate (No. 421, September 13, 2013). Weed control is an important aspect of pasture management.
Timing of herbicide application depends on the life cycle of weeds. For example, annual weeds can be controlled in the spring, whereas, biennial or perennial weeds can be killed by herbicides in the fall and spring. If herbicides are sprayed on some perennial weeds still actively growing in the fall, herbicides can be more readily transported into the root system and be more effective at killing the weed than if the herbicide was applied during the heart of the growing season. An application during the heart of the growing season may only damage the top growth of the weed, but not kill the plants.
For controlling the following perennial weeds, herbicide options include:
Spraying with 2,4-D would work for most biennial weeds such as bull thistle, common burdock, poison hemlock, and musk thistle.
Check labels for grazing restrictions for any herbicide used. Desirable legumes will probably be killed or damaged by most herbicides with a waiting interval before replanting.
Walt Fick, Range and Pasture Management Specialist