What can I use to kill weeds around my seedling spruce? This is the question for the past week. I have many producers call wanting a control for the broadleaf weeds coming up around their young Colorado and Black Hills spruce seedlings. At this time of year we are looking at post-emergence herbicides to control weeds that have become established. While some herbicides are labeled for semi-directed applications, now is not the time to apply them. Clopyralid (common sold as Stinger) is a broadleaf herbicide that can be used around conifers (but not most deciduous trees) and the one most people have called about using. While it is labeled for use during the growing season; it is still best to wait until after the new growth has fully expanded and the needles hardened, which is a month or so away – later is better. If applied when the foliage is tender it will result in tip curling and dieback. I also do not recommend it be used as a semi-directed spray; put it on the ground, not over the trees. The label rate must be absolutely followed with blue spruce, do not even think of exceeding the rate, and don’t use a surfactant. Also damage can occur in first year plantings of any evergreen, so use caution. A final reminder, Stinger is labeled for control of weeds in Christmas tree plantations.
