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Protect trees from herbicide drift

Herbicide drift damage is a common problem, especially in deciduous trees in agricultural areas. Such damage can be recognized by distorted foliage, such as leaf cupping, curling and twisting; stunted or twisted stems; defoliation and dieback of branches; discolored leaves; or stunted shoots and leaves.

While these are signs of possible herbicide damage to trees, there are other problems, such as insects and diseases, that can cause the same symptoms.

Some of your farm or windbreak trees may be more susceptible to herbicide damage than others. I have always found that hackberry trees are among the first to show symptoms and serve as a “sentinel tree.” Other sentinel species, especially in areas like southeastern Nebraska, include redbud and oak, to name a few.

Understand herbicides

All types of herbicide formulations can cause drift damage to trees, including volatile products such as 2,4-D and dicamba, which form a gaseous vapor – even days after application – that can volatilize in warm temperatures and travel long distances from the site of application to the place of application. cause damage to non-target plants.

Contact herbicides such as glyphosate are thought to be less dangerous to trees, but remember that these are non-selective and can kill any plant they encounter. Caution should be exercised when applying such herbicides around sensitive plants and young trees. In addition, many glyphosate products also contain additional residual active ingredients that can be absorbed by the roots.

Related:Treat the suckers of the trees around the farm

According to a Nebraska Forest Service (NFS) publication by Laurie Stepanek, Justin Evertson and Kyle Martens on this topic, it is appropriate to be particularly careful with products labeled for the control of brush and woody weeds because they normally can cause significant damage to trees. .

“Even trees some distance from the application site can be affected, as tree roots can extend well beyond the tree canopy,” the release said.

Evertson, green infrastructure coordinator for the Nebraska Statewide Arboretum, recommends special care when applying products containing triclopyr (Garlon, etc.) and picloram (Tordon) around important specimen or farm trees and woodlands.

“They are both used to control woody shrubs and are very damaging to trees,” he says. “Picloram is especially problematic because it can be transported from the soil to non-target trees by drift or leaching, and it can persist in the soil for many years.”

Although agricultural activities are often blamed for herbicide damage to trees, several lawn and household herbicides are used to control dandelions and other invasive lawns, which are often the real cause of injured trees.

What can we do?

NFS staff suggests several tips to reduce the potential damage from herbicides to your trees or to other sensitive locations such as area vineyards or adjacent plant and tree nurseries:

Follow instructions. It should go without saying, but read and follow all directions on herbicide labels – whether in the field or around the farm – especially if you are using herbicides that are known to evaporate and run off.

Know sensitive sites. When applying herbicides, pay attention to the environment. In Nebraska you can visit driftwatch.org to learn about sensitive locations such as vineyards, organic farms, native forests and plant nurseries near the site for herbicide applications; and be especially careful with sensitive trees around your own farm.

Take care when applying to lawns. Homeowner herbicides contain many of the same active ingredients that can cause damage to trees. Be aware of these herbicides and understand their potential when applying them to lawns and gardens near farm trees.

Go fall. This is not always possible, but the time of new tree growth in the spring is the time of most herbicide problems. Moving some herbicide applications to the fall where possible can significantly reduce potential damage.

Avoid wind. Warm temperatures and windy days can easily cause drift issues, so make sure you as an applicator monitor temperature, wind speed and direction to avoid drift issues.

Spray coarsely. Adjust the nozzles to a coarse droplet size around sensitive areas, rather than a fine droplet size.

Do not apply too much when treating stumps. If you are treating stumps around areas with sensitive trees, be careful not to use too much, as the treatment chemicals can move from the stump’s roots into the soil.

Think long term. It is true that many trees, especially young trees, can be killed by one incorrect use of herbicides, but it is often the case that these trees can recover from repeated minor damage. However, if the same damage is repeated year after year, it can ultimately shorten the lifespan of any susceptible tree.

For help identifying herbicide drift damage, contact your local forest service, extension office or state Department of Agriculture.

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