Do You Need to Control Sagebrush? These Observations Could Help Prevent Costly Errors
Posted on: Sep 18, 2013
We regularly receive calls from ranchers who are concerned that excessive sagebrush is reducing grass production. They worry that too much sagebrush is resulting in a reduced stocking rates, thus depriving them of revenue. These are valid concerns, but ranchers should consider the tips below that can help prevent costly sagebrush treatment efforts if they are unwarranted.
1) Should your pastures have sagebrush? Sagebrush tends to thrive in the West, with its combination of soils and precipitation, so your efforts to totally rid a pasture of sagebrush may require costly effort to battle natural successional processes. Further, recognize that sagebrush can provide benefits such as trapping wind-driven snow in winter and providing wildlife cover year-round. If you don't like sagebrush, it doesn't mean you're not benefitting from its presence.
2) How much sagebrush should your pastures have? A good way to answer this question is through the percent canopy cover of a sagebrush stand. A handy rule of thumb is this: at 30% canopy cover, sagebrush becomes hard to walk through. This is also the level of canopy that may lead you to consider treating sagebrush. Depending on such variables as your ranch's objectives, soils, precipitation, slope, aspect, and other plant species, at or above 30% sagebrush canopy cover, you may think about a treatment plan.
3) Are you gaining more sagebrush over time? A simple way to determine if you are gaining more sagebrush is to observe different age classes of these plants. Since we often don't know how old individual sagebrush plants are, dividing them into groups of plants based on age can be helpful. There are 4 age classes: seedling, young, mature, and decadent. The first and last are fairly easy: seedlings are brand new plants endeavoring to grow in their first season of life, and decadent plants appear to be nearly dead. You next need to decide if sagebrush plants are young or mature. This can be tricky, and size of the plant is not always a good indicator of age. A helpful trick is to cut a piece of sagebrush, dab a little water or oil on the stem, and count the rings, just as you would age a tree. Decide how old the plant is based on the number of rings you count (sagebrush can live for decades, meaning the division between young and mature plants then becomes fairly easy). The point of dividing the plants into age classes is this: if the sagebrush stand shows many decadent individuals, then pursuing a costly control treatment may be unwarranted. We have observed such decadent sagebrush stands in Montana, Wyoming, Colorado, and Nevada in the past two years and caution clients not to pursue costly vegetative treatments when mother nature is turning the sagebrush stand over on her own.
If you decide to pursue a sagebrush treatment after considering the three above tips, the next step is to determine how to treat it. You can mechanically treat sagebrush, spray it, or burn it. Each of these options has an associated cost, and can greatly alter the fundamental biological processes of a pasture, so much thought should go into choosing the best way to treat sagebrush. This is stage is where it is advisable to seek a professional opinion and put considerable thought into choosing the correct tool for your situation.
Lastly, the post-treatment grazing program should be carefully managed after sagebrush is treated. Plants such as desirable perennial grasses may benefit greatly in the absence of sagebrush, so much care should be taken to not expose them to lengthy grazing durations and/or heavy utilization rates. Poor grazing management following a sagebrush treatment creates the conditions for more sagebrush to grow, which shortens the lifespan of the treatment and drives up costs.
As an example, consider the photo below, taken in 2013 on a Montana ranch.
A walk through this sagebrush revealed that it was becoming hard to walk through, meaning canopy cover was in the neighborhood of 30%. This means the ranch should think about corrective action. However, a high percentage of the sagebrush plants in the area were decadent (some of these may be seen in the photo foreground), and younger plants were missing. Several blue grouse were also flushed from this stand, meaning it was providing good bird cover. Given these observations, managers decided not to control the sagebrush, but to continue watching it though time. This was a good move, which prevented the need for cash outlay for the treatment.