Invasive Species of Indiana

Palmer Amaranth Video
Garlic Mustard (Alliaria petiolata)
Garlic mustard, an invader of forests across the eastern U.S., is a biennial herb that was introduced from Europe in the 1860’s.  During its first year of growth, the plant forms a low growing cluster of distinctive kidney-shaped leaves.  It grows up to 40 inches tall in its second year, and can be recognized by its 4-leaves with toothed edges.  Garlic mustard plants produce copious seeds, with as many as 3,000 seeds per plant.  These seeds can survive for up to 10 years in the soil, creating a lasting problem at invaded sites.  Garlic mustard alters the chemistry of the soil where it grows by adding chemicals to the soil that prevent the growth of other plant species.  In invaded areas, garlic mustard forms a single-species carpet on the forest floor. 
Spotted Knapweed
It was introduced from Eastern Europe in the early 1900’s mixed in with crop seed. Spotted Knapweed is a short-lived perennial herb. This plant can grow 1-2 feet tall with grayish hairy leaves. During its first year, it will grow just as a rosette. The Flowers are thistle-like and can be pink to purple. This species threatens savannas, grasslands, sand dunes, and prairies. It can cause a serious decline in forage and crop production. It does this by releasing a toxin that reduces the growth of other species. Spotted Knapweed is a high seed producers and its seed can remain in the soil for five or more years. This invasive is primarily spread because of humans. It is usually spread through hay and vehicle under carries. Producers and citizens can help by learning to identify this invasive. It is important that invasive species are kept under control. This saves more money as well as some of most beautiful native species.
Vinca minor is a perennial, evergreen herb that matures at about 6″ tall and stems that continue to elongate each year to many yards in length. It exhibits a trailing mat, prostrate mat or mounding mat growth habit and has a medium growth rate. Its leaves are evergreen, elliptic and dark green above with a subtle white mid-vein. The flowers are predominantly blue-purple, originate from the leaf axils, composed of five fused pinwheel-like petals and a short tubular throat. They bloom in late March and April and sporadically throughout the growing season.
Once established, Vinca minor forms a dense carpet to the exclusion of other plants. This creates a problem where it is competing with native flora. In ideal growth conditions, Vinca minor can spread with great rapidity by means of its arching stolons, which root at the tips. Dry or cold weather may temporarily set growth back, but it quickly resprouts and regains lost grown coverage. It grows most vigorously in moist soil with only partial sun, but it can grow in the deepest shade and even in poor soil.
Periwinkle can be pulled, raked, or dug up, though resprouting will occur. It can also be cut or mowed in spring during its rapid growth stage followed by a foliar application of glyphosate on the resprouts. Herbicide alone can be used as a control method. Thoroughly wet all leaves triclopyr (Garlon 3A) or glyphosate (Roundup) mixed according to label directions at the highest allowed rate plus a nonionic surfactant. This should be done between July to October for successive years. In winter, herbicide treatments should be limited to days when the high temperature exceeds 50 degrees F. No biological controls are known.

Invasive plant control – general

TNC Wildland Weeds website with information on all control methods, specific information on invasive plants

Invasive plant control – tools and herbicides

(Note – these are examples and do not constitute endorsement of these particular brands or companies)

Forestry Suppliers: wide range of tools, herbicides (e.g. Garlon 3a, Garlon 4, Roundup, dye, and supplies 1-800-647-5368
Honeysuckle Popper uses leverage to remove bush honeysuckle and other invasive shrubs
Townsend Chemical extensive inventory of herbicides and basal bark carriers (like Ax-it) 1-800-616-4221,
Gamma Seal Lid – lock tops for 5 gal. buckets, 1800-842-6543

Controlling aquatic invasive plants

Aquatic Management Guide
Aquatic Plant Management by Carole Lembi; good summary with photos, identification information, control options