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Don't ignore those honey-locust trees in pastures

5/25/2014

A thorn in your side is a common phrase we all have heard. Today's farmers and ranchers can relate to this when it comes to thorny honey-locust trees that can take over certain pastures where they are growing if not controlled.

Locust trees and other undesirable brush species can invade and compete with desirable forage for moisture, light and nutrients, and can be a main limitation to rangeland production. Dense brush stands obstruct grazing, reduce livestock performance and interfere with livestock handling. Removing trees and brush from rangeland can increase forage production and livestock carrying capacity.

Brush invasions frequently are ignored until they become severe. Control can be difficult and expensive, and the cost of attempting to eradicate a species usually exceeds any benefits gained, once they have gotten out of hand. That is why it is best to remember this now and make it a year-round priority, just like you do with thistle control, to stay on top of brush control now before it gets out of hand.

There are basically five different methods of using herbicides to control tree and brush species that can be used, and their effectiveness also depends on what time of the season you are targeting the plant pest. For example, to use a foliar application, it is best to apply the herbicide in the spring when brush is nearing full-leaf stage and growing actively. A dormant stem application obviously is done when brush is dormant and the bark is dry. Soil application is best to apply from April through June during the period of active growth. Basal bark application and cut stump or frill application best is done from mid-July to mid-January. Mowing or cutting re-sprouting trees such as honey locust and hedge without spraying an herbicide only will increase production of sprouts and lead to more problems.

Keith Harmoney, range scientist at the Kansas State University Agricultural Research Center in Hays, is conducting a large-scale replicated field trial to control honey locust. A total of 500 trees were treated Sept. 10, 2012, and Aug. 21, 2013, using the cut stump and basal bark methods with different types of herbicides to evaluate effectiveness. The field trial is not yet complete because rating the percentage of control during two growing seasons is necessary in order to fully assess if the trees are killed completely with no re-sprouts.

These first year results of control in 2013 are quite promising. After one year, bark and thorns of many controlled trees already were peeling. By the third year after treatment, a majority of the thorns and bark should be peeled from controlled trees and make them more desirable for use as firewood. Final results will not be available until after the summer of 2015.

It is important to emphasize when honey-locust trees are cut, the herbicide should be applied immediately. The stump soon will seal over with a thin protective sap. Usually, treating the entire surface area of the stump is not required; treating completely around the outside edge of the stump is sufficient for most herbicides. However, the label requires treating the whole bark area to the soil surface for some herbicides. The basal bark application is accomplished by spraying the basal parts of brush or trees from the soil surface to a height of 15 inches above the ground. Thoroughly wet all basal bark areas, including crown buds and ground sprouts.

Always read and follow the herbicide label directions, and make sure oil carriers form a compatible mix with the herbicide being applied.

Brand names appearing in this article are for product identification purposes only. No endorsement is intended, nor is criticism implied of similar products not mentioned.

If you have additional questions, contact Keith Harmoney at (785) 625-3425, Ext. 221, or your local K-State Research and Extension county office.

Stacy Campbell is agriculture Extension agent in Ellis County.

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Herbicide Mix-Application Method Herbicide Rates - v/v Avg. % Dead Trees

Remedy/diesel - basal bark 25% Rem, 75% diesel 78%

Milestone/oil - basal bark 5% Milestone, 95% oil 100%

Milestone/water - cut stump 10% Milestone, 90% water 98%

Dicamba/2,4-D/water - cut stump 33% Dicamba, 2% 2,4-D, 65% water 98%

Remedy/diesel - cut stump 25% Rem, 75% diesel 58%