January 18, 2022

Manage invasive plants: Southwest Purdue Ag Center tackles invasive species

VINCENNES, Ind. — The team at the Southwest Purdue Agriculture Center is tackling invasive species while increasing pollinator habitats.

“Some of the invasive plants we found include common vines, Japanese honeysuckle and wintercreeper,” said Will Drews, natural resource specialist at Knox County Soil and Water Conservation District.

Drews gave a presentation at the virtual SWPAC field day.

The team also found tree of heaven, white mulberry trees, garlic mustard and several other invasive plants. They use a combination of manual and mechanical removal, followed by herbicides.

Pruning or handsaws are helpful for taking down vines like wintercreeper or Japanese honeysuckle. They can also cut through small to medium-sized bushes.

“A nice, heavy-duty lopper with a 3-inch capacity is good for getting through multi-stemmed shrubs,” Drews advised.

Chainsaws are used on larger shrubs, and brush cutters can make quick work of dense thickets.

“When we do make cuts, we follow up with herbicide applications to make sure that the stems do not regrow, which is especially problematic with most of our woody species,” Drews said. “We call it a cut stump technique.”

Another technique used is foliar spray applications. This method is used primarily on smaller shrubs or vines.

Basal bark applications, in which the herbicide is mixed with an oil carrier instead of water, are applied around the trunk of a tree or shrub. It soaks into the bark and kills the tree without the applicator having to do any manual or mechanical cuts.

The main herbicides used are glyphosate or triclopyr.

“For a couple species like garlic mustard and smaller invasive shrubs, we’ve done some manual pulling removal,” Drews said. “Especially in sandy soils, it’s super easy after a rain.”

Examples of invasive plants found in southern Indiana include:

Tree of Heaven: Tree of Heaven is an invasive tree that can crowd out native trees and damage roads and sidewalks. It has an unpleasant smell and its sap can cause heart issues in some people. Prevent its spread by carefully removing from property.

Invasive honeysuckles: Invasive honeysuckles include several species of vines and shrubs from the genus Lonicera that grow quickly, covering large areas, shading out native plants and girdling or weighing down trees. Prevent its spread by removing it from property and checking clothing for seeds.

Garlic mustard: Garlic mustard can take over the understory of forests, interfering with the growth of native plants and acting as a reservoir for damaging plant viruses. Prevent its spread by removing and properly disposing of plant material.

Wintercreeper: This exotic invasive vine is moving from ornamental planting to fields and woodlands and features a white to pinkish-red fruit that is visible from September to November.

Callery/Bradford pear: Bradford is an environmentally devastating tree that crowds out Indiana’s native plants by taking over forests and parks. Its white flowers have an unpleasant odor, some escaped trees are aggressively thorny and the branches easily split and fall. Consider planting native alternatives to help prevent its spread.

Learn more at ag.purdue.edu/reportinvasive.

Erica Quinlan

Erica Quinlan

Field Editor