PIP Posey Invasive Partnership

09/07/2026

Invasive Plant of the Month: Japanese Chaff Flower (Achyranthes japonica (Miq.) Nakai


Description: Japanese chaff flower is native to east Asia. How it was introduced to North America is unknown, but the earliest record of its occurrence here is from eastern Kentucky in the early 1980s. Japanese chaff flower, hereafter referred to as chaff flower, is a member of the Amaranth family. It is a perennial herb that can reach heights of 3-6 feet. It forms very dense stands. Mature plants have extensive root systems supporting multiple stems. Chaff flower begins growing in late spring and flowers in late July. The leaves are simple, opposite, and the “arcing” venation is very similar to that of dogwood leaves. Stems and leaves are smooth to slightly pubescent (fuzzy). Seedlings have red stems. Some of this red tint persists in the stems as the plants grow, particularly at the branch nodes. It is most readily identified by its erect “bottle-brush” flower spike on which fruits are formed. Flowers lack petals and occur in a tight cluster at the end of the spike. As the spikes elongate in mid-August, the fruits develop, turn downward and eventually lie flat against the spike stem. Each fruit has a pair of stiff bracts that readily attach to clothing or fur to aid in dispersal. Floodwaters facilitate long distance dispersal of seed. Chaff flower leaves senesce in the fall and the bare opposite-branched stems turn straw to brown in color with the elongated fruit spikes intact. Fruits remain on the dead stalks through most of the winter until animals or people brush against them or the stalks are broken down by snow or floodwaters. Chaff flower may be confused with white vervain, lopseed, or one of the pigweeds. When in bloom, white vervain flowers have white petals, while chaff flower has no petals. W. vervain also has coarsely toothed leaf margins, while chaff flower leaf margins are smooth. Lopseed, like chaff flower, has an opposite leaf arrangement and small fruits closely appressed to the flower stalk that are similar in appearance to those of chaff flower. Lopseed differs in that it has coarsely toothed leaf margins and pale pinkish to purple flowers. Its fruits are arranged in an opposite pattern along the flower stalk, while those of chaff flower are in an alternate arrangement. Pigweed has alternate leaves, while those of chaff flower are opposite.

Distribution: First reported in Indiana in 2002, chaff flower now occurs in every Indiana county bordering the Ohio River. It is mainly restricted to the Ohio River flood plain. Some populations have been found beyond the Ohio River flood plain. Impact: Chaff flower’s tall growth habit and dense infestations easily shade out and displace many native plant species. It is typically found in flood plains, ditches, bottomland forests and on riverbanks, growing in rich, moist soil. It prefers partial shade. However, it tolerates full shade, drier upland soils and sunnier conditions on roadsides, field edges and vacant land in urban and industrial areas. It occurs less frequently in open, full-sun environments. Chaff flower spreads quickly along waterways and public areas such as trails. It does not tolerate annual flooding or prolonged periods of inundation. Thus, in bottomlands, it is most commonly found on the first terrace above, or on the edge of, the annually flooded zone.

Management: Recommendations for chaff flower control are still in development. However, the methods below have shown some initial success. In all cases, control should be conducted before chaff flower produces seed in late August/early September. In the Ohio River floodplain, frequent flooding deposits new chaff flower seed, making management in these areas difficult and control less feasible. Efforts should focus on high priority floodplain habitat and infestations outside the immediate Ohio River floodplain. Prevention: Chaff flower seed can inadvertently be spread by mowing, road maintenance or agricultural equipment. Mow infested areas along roadsides, ditch banks and field edges before seed matures. Chaff flower seed maturation may vary from year to year depending on weather patterns. In southern Indiana, mowing should occur from May through mid-August. Avoid working or recreating in or walking or driving through infested areas during seed dispersal periods. Clean clothing, shoes, ATVs or vehicles following activity in infested areas.


Control:
• Manual - control is feasible only for the occasional plant, small infestations or sensitive areas where herbicides cannot be used. The vigorous root system makes hand pulling difficult. Digging may be required to successfully remove the plant. The seed head may be removed to prevent further spread. All plant parts, especially seeds, should be bagged and disposed of.
• Mechanical — Mowing and cutting can be used to prevent flowering and seed head establishment but has not been shown to kill established plants.
• Chemical — Foliar applications of a 2 percent solution of triclopyr (at least a 44 percent active ingredient concentration) or glyphosate (at least a 41 percent active ingredient concentration) herbicide have been effective if applied before or during flowering around mid-August. A non-ionic surfactant should be used to increase herbicide uptake. Since chaff flower often grows in riparian areas and may occur on stream and riverbanks or near open water, caution must be used to follow label restrictions regarding overspray, drift or movement of herbicide into surface waters. Only herbicides and surfactants with an aquatic use label should be applied in these circumstances. Accord, Rodeo, Aquaneat (i.e., glyphosate products) and Garlon 3A and Element 3A (i.e., triclopyr products) are labeled for use in or near aquatic areas. Other herbicides having formulations with aquatic use labels such as 2,4-D and imazapyr (Habitat and others) may be effective on chaff flower, but have not been tested.
Maintenance: Follow-up treatments will be required, as seeds already present in the soil will sprout.
IMPORTANT: The pesticide label is the law! When using any chemical control, always read the entire pesticide label carefully, follow all mixing and application instructions and use all personal protective gear and clothing specified. Contact the Office of Indiana State Chemist (OISC) for additional pesticide use requirements, restrictions or recommendations.

05/07/2026

Most caterpillars that show up in gardens aren't pests—they're future butterflies and moths. Some also feed birds and support a healthier ecosystem. Before you remove one, take a moment to identify it first.

Tomato hornworm. This large green caterpillar becomes the five-spotted hawkmoth. If you spot tiny white cocoons on its back, leave it alone. Those are parasitic wasp cocoons, and they'll help control future hornworm populations naturally.

Parsley worm. The green, black, and yellow caterpillar on parsley, dill, and fennel becomes the eastern black swallowtail butterfly. Plant a little extra of these herbs. There's enough for both you and the caterpillars.

Eastern tent caterpillar. Those silk tents in cherry and apple trees look messy, but these caterpillars feed nesting birds early in the season. Healthy trees usually leaf out again once feeding ends.

Gulf fritillary. Bright orange with black spines, it looks intimidating but doesn't sting. It feeds on passionflower vines and becomes a brilliant orange butterfly worth the chewed leaves.

Woolly bear. This fuzzy fall caterpillar becomes the Isabella tiger moth. It mostly eats grasses, weeds, and low plants—not your vegetables. It survives winter with remarkable cold tolerance.

A chewed leaf isn't always a loss. Sometimes it's just the beginning of a butterfly.

05/07/2026

Chemical sprays aren't the only answer to garden pests. Building a system where beneficial insects do the work is slower but more stable.

Certain plants attract helpful predators. Yarrow and dill bring in ladybugs and parasitic wasps that hunt aphids. Cilantro and fennel draw wasps that target cabbage worms. Alyssum, cosmos, and marigold support lacewings and pirate bugs. These flowers also feed ground beetles and tachinid flies that manage slugs and tomato worms.

The key is leaving room for the whole food chain. If you spray everything, predators starve. Let some pests stay so beneficial insects have a reason to stick around. A diverse garden with mixed plantings gives them shelter and breeding space.

It takes patience. You won't wake up to a pest-free garden overnight. But over time, the balance shifts. Pests still show up, but they're managed by the insects already living there.

10/06/2026

If this plant is growing in your yard, ditch, or along your fence line, don't ignore it.

Poison hemlock is one of the most common invasive plants along roadways, and this time of year it's hard to miss with its tall stems and clusters of white flowers. The problem? It spreads quickly, crowds out native plants, and is very toxic.

Knowing how to identify poison hemlock is the first step to protecting your family, pets, and local ecosystems. Check out this week's Invasive Plant of the Week graphic to learn what to look for and help stop its spread before it produces thousands of seeds.

Have you spotted poison hemlock in your neighborhood this year? Let us know in the comments!

For more information on invasive species please visit sicim.info

04/06/2026

04/06/2026

Invasive Plant of the Month - Japanese stiltgrass

Japanese stiltgrass (Microstegium vimineum), also called Nepalese browntop, is an aggressive invader of forest lands throughout the eastern United States. Infestations can impact the diversity of native species, reduce wildlife habitat, and disrupt important ecosystem functions. Stiltgrass is considered one of the most damaging invasive plant species in the United States. Infestations spread rapidly and the seed can remain viable in the soil for up to five years.

Correct identification is necessary before beginning any management activities. Fortunately, Japanese stiltgrass has a unique combination of characteristics that make field identification possible. This publication gives simple descriptions and clear pictures of these characteristics along with details on how to distinguish several common look-a-like species. For more information on Japanese stiltgrass ecology management, visit www.rtrcwma.org/stiltgrass or www.invasive.org.

Identification-
Stiltgrass is a weak rooted and sprawling annual grass that can grow to heights of 6 feet, though it is usually much shorter. Taller plants typically lie flat along the ground or propped up against other vegetation. Plants usually have multiple weak stems, with aerial rootlets near the base, giving rise to the common name ‘stiltgrass’. The leaves are short with smooth edges and a noticeable silvery midrib on older leaves. The flowers and fruits are borne on thin spikes on the top of a delicate stem. Stiltgrass also has closed (cleistogamous) flowers that are self-fertilized. These occur on short branchlets in the lower axils. In the fall, the tops of the plant turn purple or brown in color, giving this plant one of its other common names, Nepalese browntop. In winter, the thatch is a distinct bright tan to orange color.
Look-a-likes-
Stiltgrass can be confused with whitegrass, nimblewill, basketgrass, crabgrass and deer tongue or panic grass.
Japanese stiltgrass (Microstegium vimineum Stock Photo - Alamy

The River to River Cooperative W**d Management Area hosted a research and management summit on the invasive Japanese stiltgrass (Microstegium vimineum) at Southern Illinois University in Carbondale, Illinois. August 11-12, 2010

11/05/2026

We had a great event picking up trash and removing a few remaining invasives on our Adopted Highway. Thanks to all the volunteers!

07/04/2026

Invasive Plant of the Month - Garlic Mustard
by Angel Okray

Garlic Mustard (Alliaria petiolate), native to Europe and Asia, was introduced to the United States as an edible herd. Escaping cultivation, it now poses a threat to native flora as it quickly invades forest floors.
IDENTIFICATION: Garlic Mustard is a biennial herb, meaning it has a two-year life cycle. In its first year, it forms a low growing rosette: a cluster of dark green, broadleaf leaves with scalloped edges growing low to the ground. In its second year, it can grow nearly four feet tall with multiple stems of triangular, sharp toothed leaves and small white flowers at the top of each stem. Garlic Mustard develops a deep, slender taproot that often has a “S” shape. Both the leaves and the roots have a distinct garlic smell when crushed.
ECOLOGICAL THREAT: Garlic Mustard is a serious threat to forest beds, an essential part of the ecosystem where insects and native wildflowers typically thrive. Garlic Mustard blooms early in the spring and can quickly become a monoculture, outcompeting native species. Its root system also releases chemicals in the soil that disrupt the underground network of fungi and even inhibits the growth of trees. An average Garlic Mustard plant produces 360 seeds, but single plants have been known to produce as many as 8,000 seeds. The seeds do not carry well in the wind, but they can spread by attaching to birds, deer, and even your boots.
CONTROL: The most effective way to kill Garlic Mustard is to remove it before it sets it seed in its second year. The taproot does not anchor into the ground well, so the entire plant can easily be pulled out of the ground. It must be bagged and removed from the woods, or it will still disperse seeds. Do not compost. Repeating treatment each year is necessary because of its biennial growing cycle. Removing Garlic Mustard in its first year is more challenging because it is harder to see in its clusters close to the ground. In this stage, it can be carefully sprayed with a low percentage glyphosate to kill the root and preventing it from returning the following year. However, it will still be necessary to revisit the site the following year to remove any plants that were missed.
FUN FACT: Garlic Mustard is considered generally safe for human consumption, but it is only recommended to eat in moderation because of its hydrogen cyanide production. Younger plants can be eaten raw, but older plants should be cooked thoroughly. This spring, you can gather some leaves from young plants and try making garlic mustard pesto!