Autumn Olive is a deciduous shrub or small tree that is highly invasive in Indiana. From a distance it can be identified by its silvery appearance. The leaves are medium green on top and distinctly silver on the underside. It was planted extensively for highway beautification and wildlife food in the 50”s and early 60’s and is spreading rapidly. It crowds out many native plants and since it fixes nitrogen it improves soil fertility to the point that many plant communities that prefer low fertility soils cannot survive. It is often called “Autumnberry” and prized by some for its food value. The fruit is high in lycopene and other nutrients. It is being grown commercially in a few places for its food value, especially for making jams and jellies. It is considered an invasive plant in Indiana and should not be planted. Control is best achieved by cutting the plant and immediately treating the stump with a systemic herbicide such as glyphosate or triclopyr and a 20% concentration..

The name Canada Thistle does not explain its origin, this really tough invasive plant originated in the Mediterranean area and southeast Europe, not Canada. Although it reproduces and starts a colony by seed, its rapid spread is by sprouts from the massive underground root system shown below. It is this massive root system that makes it difficult to control. Canada Thistle grows profusely along roads, in pastures, along edges and in crop fields, in flower beds and any where a seed can get in contact with the soil. Control is best accomplished with a systemic herbicide such as glyphosate when the plant is in the rosette stage in the spring or fall. Usually takes several treatments and sometimes 2 or 3 years to get control.

A native of central Europe, Norway maple has escaped cultivation and forms monotypic populations by displacing native trees, shrubs, and herbaceous understory plants. Once established, it creates a canopy of dense shade that prevents regeneration of native seedlings. It is considered one of Indiana’s unwanted invasive plants. Do not plant this tree. The purple leafed maple is also a variety of Norway Maple. Its shallow root system dries out topsoil and prevents grass and other plants from growing under the tree. It is considered to be highly invasive because of its heavy seed production. The best control measure is pulling seedling and the cut stump method and application of a systemic herbicide containing at least a 30% concentration of glyphosate or triclopyr active ingredient.

Palmer amaranth is a native to the southwestern deserts of the US and has invaded Indiana in the last few years. Palmer amaranth is a green, flowering plant that has caused widespread damage in cotton production in southern states. Most populations are glyphosate-resistant, and the weed thrives in summer heat and can reach heights greater than 7 feet. It is a rapidly growing member (as much as 2 1/2 inches per day) of the Pigweed family. It closely resembles other pigweed species, but no other pigweed has flower and seed panicles over 1 and 1/2 feet in length. Male and female plants grow close together with the male plant having a soft panicle to the touch while the female panicles are bristly to the touch. Extreme caution should be taken in the possible movement of seed by combines and other harvesting equipment.

The traits that made the Purple Winter Creeper a great ornamental have now caused it to become a highly invasive plant. Those traits included rapid growth, evergreen color, glossy leaves and tolerance to harsh growing conditions. It out competes native plants by blocking sunlight, depleting soil moisture and nutrients, and by forming such a dense mat that it impedes or stops the growth of native plants. Vines growing vertical on trees can eventually overtop them and stop photosynthesis by the tree. Control is best achieved by injuring the plant with a weed eater, lawnmower or other tool and spraying the plant with a systemic herbicide such as glyphosate or triclopyr.

Asian Bush Honeysuckle. Prolific fruiter. Fruit or berry turns from green to black to red/orange as it matures and is high in carbohydrate which is detrimental to migratory birds. Migratory birds need high protein and high fat diets to prepare for long migratory flights. Has an allelopathy effect on other plants causing understory plants to die out resulting in total domination of a site by the honeysuckle.. Does not host native insects reducing available food for birds. Grows profusely along roads often creating traffic hazards especially at intersections. Fairly easy to pull small plants growing in moist soil due to shallow root system. Cutting stems low to ground and treating stumps with a systemic herbicide like glyphosate, triclopyr or picloram is the most common treatment to eliminate the plant. Control is a long term project due to seed in the ground and the spread of seed by wildlife.

Japanese Barberry is a dense, spiny, deciduous shrub that when it escapes from cultivation is highly invasive and damaging to natural ecosystems. It forms dense stands in woodland areas as shown in the photo below where it shades and outcompetes all natural vegetation. It can also be found invading pastures, open land, marshes and roadsides. Once established it shades out native plants and almost eliminates wildlife from the area. Deer will not browse it and move on to native trees damaging them for future timber purposes. Smaller plants can be controlled by removal of the plant and all roots. Regrowth from root fragments is a problem. Larger areas are best treated with a systemic herbicide containing glyphosate or triclopyr as a foliar sprayer or treatment of cut stumps.

Common or European Barberry is a similar invasive plant that has the additional concern of being the alternate host for black stem rust of small grains. Control measures are the same.