sucker kill

Asked February 13, 2020, 6:42 PM EST

What can I spray on the alder stumps to kill the many sucker that is coming on. What can I spray, What time of year , how much?

Clackamas County Oregon

1 Response

First I should note that the vigor and viability of stump sprouts from red alder is very dependent on the size and age of the alder that was cut. Older, larger alder trees (>30 years, >6 inches diameter) usually produce sprouts of low vigor and viability. Younger and smaller alder produce more vigorous sprouts. So if the cut alders were older trees, you may not need to do anything other than favor desirable vegetation to take over the growing space vacated by the alder.

If you do wish to use a foliar spray or a basal bark spray to control alder stump sprouts, you have several options for herbicides and season of use. These are described in the PNW Weed Management Handbook and
For information on specific herbicide ingredients, trade names and properties, see

Much depends on the presence and species of desirable vegetation in proximity to the alder. To minimize herbicide damage to desirable vegetation, you need to know the sensitivity of desirable vegetation to your herbicide options and take proper precautions in choosing herbicide along with rate and season of application.

Note: The attention given to herbicides here does not indicate an advocacy for their use but an acknowledgement that using herbicides presents some unique risks, and that landowners and managers need to know enough about them to make informed decisions on their use.

Trade-name products are mentioned as illustrations only. This does not mean that the Oregon State University Extension Service either endorses these products or intends to discriminate against products not mentioned.

Use pesticides safely!

• Wear protective clothing and safety devices as recommended on the label. Bathe or shower after each use.

• Read the pesticide label—even if you’ve used the pesticide before. Follow closely the instructions on the label (and any other directions you have).

• Be cautious when you apply pesticides. Know your legal responsibility as a pesticide applicator. You may be liable for injury or damage resulting from pesticide use.