Kudzu Control• The History of the

Invasive • Strategies in Missouri

and Illinois• Integrated Herbicide

Techniques• Bioherbicides

• Kudzu is a leguminous perennial vine belonging to the Fabaceae family.

• Foliage is alternate and compound (trifoliate) with 2-3 lobed leaflets.

• Kudzu forms tuberous root systems characteristically reaching a soil depth of 1-3 m (3-9ft). Roots have been documented to 17.8 cm (7 in) in diameter or larger.

• First year kudzu vines, leaflets, and seed pods are diagnostically pubescent, covered with yellow hairs.

• In Missouri, blooming occurs in August through September.

• Seed pods are evident in October.

Leaves have a distinct mitten shape and trifoliate arrangement.

Flowers have a grape scent (similar to “grape koolaid”) and are long, distinct racemes that resemble pea flowers in shape.

Kudzu grows well under a wide range of environmental conditions but greatest growth is achieved when winters are mild, summer temperatures rise above 80 degrees, and rainfall is abundant.

New growth may exceed one foot or more per day at the peak of the growing season.

Forest edges, disturbed areas, and right-of-ways are preferred “habitats”.

Native to east Asia, Kudzu was introduced to the eastern and southern US in the late 1800’s.

In the early 1900’s, kudzu was promoted as an inexpensive forage, an erosion control solution, and was available through mail order as a trellis vine.

The Soil Erosion Service (Agriculture and Soil Conservation Service) distributed approximately 85 million seedlings starting in 1933 in an effort to curb soil erosion.

Monetary incentives for establishment were prevalent (Bailey 1944.)

By 1946 kudzu had been planted on nearly 1.25 million hectares.

In 1993, a Congressional report deemed kudzu as one of the most harmful non-indigenous plants in the US.

Land productivity losses have been estimated at $336 million per year for ~2.84 million infested ha. With weed control operations added in; an additional $81 per hectare per year. (Miller 1997)

Today kudzu infests over 8 million acres of land. One estimate suggests that it spreads at the rate of 150,000 acres annually. (USDA 2009)

It is also estimated that control costs increase by $6 million annually.

(USDA 2009)

In 1953 the USDA removed kudzu as a cover plant. It was listed as a common weed in 1970.

Today kudzu is addressed by state noxious weed laws. Missouri recognized kudzu as a noxious weed in 2003.

One of the first states to actively pursue a state-wide kudzu eradication program was Illinois. It was believed, that due to the limited distribution of the plant in the State, that control could be readily achieved.

Populations were discovered from the Shawnee Hills to downtown Chicago.

Biologists and applicators soon learned a great deal about combating this pest plant.

Strategies in Missouri and IllinoisIn the 1990’s biologists and scientists in Illinois began to take notice of the kudzu problem; by 2000 it was estimated that 100 acres of Shawnee National Forest lands were invaded, as well as widely scattered state and private land patches.

In 2001, over 105 kudzu sites were recognized in the state.

Kudzu is address in the Illinois Noxious Weed Law and by the Illinois Exotic Weed Act.

Illinois Exotic Weed Act Conservation (525 ILCS 10/) - Illinois Exotic Weed Act. The Illinois Exotic Weed Act makes it unlawful to buy, sell, offer for sale, distribute, or plant seeds, plants or plant parts of listed exotic weeds in Illinois

Illinois Noxious Weed Law Section 220.60 - Noxious Weeds State of Illinois noxious weeds include one forest invasive: Kudzu (Pueraria montana ).

Missouri Revised StatutesChapter 263 Insect Pests and Weeds Section 263.232

“(2) To control the spread of kudzu vine (Pueraria lobata), which is hereby designated as a noxious and dangerous weed to agriculture, by methods in compliance and conformity with the manufacturer's label instructions when chemical herbicides are used for such purposes…”

Kudzu is identified as a Missouri Noxious Weed, in Chapter 263 of the Missouri Revised Statutes.

• Kudzu is a Noxious Weed in Florida, Illinois, Kansas, Kentucky, Mississippi, Missouri, Pennsylvania, Texas, and West Virginia.

• It is Banned in Connecticut and Prohibited in Massachusetts.

• Kudzu is a Quarantine and “A” Designated Weed in Oregon and Washington.

• It can be problematic in all Mid-South states in almost all habitats except aquatic areas.

• Kudzu can host Asian soybean rust, a potentially serious pathogen in soybeans [Glycine max (L.) Merr.].

Illinois initiated a Kudzu eradication program and IDNR personnel began to actively contact landowners. Control was provided at no cost to landowners with infestations.

The Illinois Exotic Species Task Force and the River to River Cooperative Weed Management Area (CWMA) had their beginnings in the kudzu control program.

Missouri’s private land services division (Missouri Department of Conservation) provided outreach and assistance to landowners.

Problematic populations and landowner requests for assistance were addressed as budgetary funds allowed.

Populations are very prevalent in Southeast Missouri. Many infestations are on ROW’s and former erosion control project areas.

Control Strategies

Due to the plant’s tenacity it is recommended that chemical control be undertaken for optimum control results.

Kudzu eradication operations should follow a stepwise process that includes foliar application, basal bark, and/or cut stump treatments.

Total control of an established population often takes a number of years.

Many populations are located on private land; requiring landowner contact and extensive outreach.

Initial treatment often involves intensive interagency coordination and landowner cooperation.

Most landowners have battled the plant for so long (with such limited success) that they welcome any help they can get.

IDNR; Shimp J.

IDNR; Shimp J.

Kudzu control operations are often limited by access and terrain considerations. Applicators must make certain considerations:

• the logistics of identifying suitable water sources;

• transporting and applying mixed spray;

• and determining how the site will be reentered for future treatment.

Other factors that need to be considered include:

• age and vigor of the infestation,

• the presence of sensitive crops,

• and waterways and streams.

Notably problematic to control, early herbicide treatments to control kudzu infestations were various and often severe.

Transline (clopyralid) proved to be the herbicide of choice owing to its less severe environmental impact and limited effects on non-target plant species.

Transline (clopyralid) has very limited activity on the majority of non-leguminous overstory tree species. It was selected as the product of choice for eradication operations.

Application rates vary from:

21oz per 100g H₂O

32oz (1 US quart) per 100g H₂O

It is recommended to apply Transline with a high quality non-ionic surfactant; 1 qt per 100g mixed spray is satisfactory for most applications.

Foliar Application

Escort at 4 oz/A; (metsulfuron-methyl) [Considered for ground application under hardwoods without spray contacting desirable foliage.]

Milestone VM at 7 oz/A (aminopyralid); [Will damage trees but will not damage grasses.]

Milestone VM Plus at 64 to 96 oz/A (aminopyralid plus triclopyr ); [Will damage trees but will not damage grasses.]

Roundup at 128 oz/A (glyphosate); [Use will damage most vegetation. Treat in areas were selectivity is not necessary.]

Tordon K at 64 oz/A (picloram); [Treat in areas were selectivity is not necessary. Safe on grasses.]

Transline at 21 oz/A (clopyralid); [May be applied over most hardwood tree species. Safe on grasses.]

Garlon 3A at 2% solution (triclopyr); [Aquatic label; will harm brush and tree species but has limited activity on grasses.]

Additional herbicide treatment considerations may include:

Control is effectively achieved through the use of “integrated herbicide strategies”. Often times foliar application is combined with cut-stump or basal bark treatments to aerial vines and root crowns.

Vine Origin Treatments

In concert with foliar treatments, basal bark and cut-stem (vine) treatments enhance control efforts.

An integrated treatment regime often includes vine origin (or root crown) searches; aerial vine removal; and basal bark and/or cut-stump treatments. An integrated approach increases efficacy and vastly improves control results

Populations are characteristically tangled “spider webs” of aerial and ground trailing vines.

But each vine has an origin that can be found and treated.

The Garlon family of products are applicable for cut-stump and basal bark treatments; other products are also suitable.

Two very diagnostic vine origins; these two examples have been treated in a cut-stump fashion.

A sharp hand saw and a hand sprayer of Garlon 4 can effectively reduce a populations viability – especially following a successful foliar treatment.

Bioherbicides?

Bioherbicides are phytopathogenic fungi and bacteria that offer promise

for the control of certain weed species.

Bioherbicides often require free moisture (or dew) for propagule germination,

penetration, and infection of host targets – various formulation ingredients

are often utilized to replace such requirements.

Myrothecium verrucaria; Strain IMI 361690

A naturally occurring fungus, Myrothecium may provide a new tool for our tool belts.

Myrothecium facts:

• originally elucidated from diseased sicklepod plants in 1998,

• spray formulations of the fungus killed 100% of kudzu seedlings and 90-100% of older plants in outdoor trials,

• Myrothecium produces cell wall degrading enzymes.

Myrothecium verrucaria also attacks hemp sesbania, sicklepod, morningglories, pigweed, redvine, and trumpet creeper.

In 2005, host-range studies showed the fungus caused little or no injury to 70%of woody plants known to occur in kudzu-infested habitats.

Dr. Doug Boyette , a research scientist with the USDA Agricultural Research Service , and colleagues were able to reduce to acceptable EPA levels the natural toxins that the fungus produces. Called trichothecenes, various cultural techniques were utilized to eliminate them from final bioherbicide formulations.

Lab results proved that the fungus could be cultured to greatly reduce the productionof toxins to commercially acceptable levels.

The lab, using liquid fermentation techniques were able to utilize the mycelium of the fungus as the inoculum.

The mycelium lasts longer than conidia based inocula and is easier to produce. A six month shelf life has been achieved with refrigeration.

The fungus is ubiquitously distributed in soils, it is not aggressive, and epidemic infestations do not occur.

The researchers have seen no recurrence of disease symptoms on plants in areas treated with bioherbicidal amounts of the fungus, indicating no significant problems of persistence or threats to nontarget hosts.

Myrothecium mycelia can be applied with a surfactant such as Silwet L-77, in the absence of dew.

M. verrucaria is compatible and synergistic with several commercially available glyphosate-based herbicides (Touchdown, Touchdown HiTech); Milestone (Aminopyralid); and for short periods of time (while in tankmix) with Transline (Clopyralid). All very important herbicides for kudzu eradication operations

Thank You.

Bob GillespieMissouri Department of ConservationSE Region2302 County Park DriveCape Girardeau, MO 63701robert.gillespie@mdc.mo.gov