This treatment is of-ten more consistent than foliar treatment. This is done in late winter or early spring, when farmers are not tied up with other field work and there is little risk to non-target plants. A small amount of solution is required, but treatment can be somewhat costly. Again, the thorns are the biggest problem. Although this treatment is used often, timing of application can have a great impact on effectiveness.
Plants are most susceptible in early summer when most farmers are busy with field crops.
Thus, application is often delayed until later in the summer when roses have hardened off. However, fall applications can also be effective. Brush over 8 feet tall is difficult to treat efficiently and may be better controlled by basal treatment or mechanical control. This probably is the least costly of all treatments. This direct application to the soil is done during the dormant season.