Basal bark herbicide applications

As referenced in the cut stump discussion last week (, there are times when we just can’t fit all of our brush control work in to the growing season. In some cases, even removal of the trees to get to a point where stumps can be treated is a time challenge in and of itself. For smaller trees (less than four to six inches in diameter), a basal bark application might be what fits the bill.

Basal bark treatments are made to the bottom 12 to 18 inches of bark of smaller trees extending from ground level with liberal coverage of the bark all the way around the tree. Products containing triclopyr or aminopyralid are the most common used. Often mixed with a carrier to enhance penetration across the bark to the cambium layer, applications can be made mid-summer to mid-winter and are a good option if you are trying to kill trees prior to removal.

Make sure you read and follow all label directions to determine if the species you are trying to control are susceptible and how product should be mixed. For example, some triclopyr products are ready to use while others vary in the amount of oil type (typically diesel fuel) carrier required (Crossbow is mixed as a four percent solution in diesel fuel – Remedy Ultra and PastureGard HL are 25-30 percent).

Aminopyralid containing products (often most effective on black and common honeylocust) are mixed at a five percent level, but have to be with a compatible basal oil and may require a jar test to check compatibility. Do not apply when soils are saturated, snow covered or frozen.

For products and mix rates, check out the 2022 KSU Chemical Weed Control Guide at Sections of the guide also are available upon request from any District Office or via e-mail to

Pruning Trees and Shrubs in the Fall

If you read the title of this news column and thought you were going to get the green light – not so fast.

Dr. Rich Marini, Penn State Extension, wrote once: “Based on everything that has been published, we can conclude that woody plants do not attain maximum cold hardiness when they are pruned in the fall.”

The reason? Woody plants are moving sugars and other materials from leaves to storage portions of the plant just prior to leaf fall and pruning could disrupt that important process.

However, he does go on to say as well: “Trees are affected more by heavy pruning than light pruning.”

In short, that means we might have some opportunities for pruning – so long as we’re at least a little bit careful.

So when will it work and when is it best to avoid? Damage is most likely to occur if we have a sharp drop in temperature before plants are completely hardened off. This could be worse on some species than others, so even though light pruning and removal of dead wood are fine this time of year, you may want to delay severe pruning until spring.

Pruning is considered “light” if 10 percent or less of the plant is removed (dead wood does not count in this calculation). Remember as well that even light pruning of spring-blooming shrubs (think lilac and forsythia) will reduce flowers for next year and should be pruned after flowering. If you’re working with junipers, remember: they do not break bud from within the plant and therefore should be trimmed lightly if you wish to keep the full shape with overgrown junipers removed.


David Hallauer60 Posts

David Hallauer is the Meadowlark Extension District agent in the areas of horticulture and crops and soils.


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