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Thursday, Apr. 17, 2014

Non-native invasive species

Sunday, July 29, 2012

As I was riding my bike along Highway 412 south of Kennett, I saw some Johnsongrass that had been sprayed and was turning color. In Missouri, Johnsongrass is classified as a noxious weed and there is a noxious weed law that the Director of the Missouri Department of Agriculture is responsible for administering through a county weed control board. The county prosecuting attorney is responsible for prosecution of all weed statutes, so designated. Another weed that is one this list is kudzu.

Although these are referred to as noxious weeds, there are also many plants, animals, insects, diseases, etc. that are classified as non-native invasive species. When alien species enter into an ecosystem, they can disrupt the natural balance, reduce biodiversity, degrade habitats, alter native genetic diversity, transmit exotic diseases to native species, and further jeopardize endangered plants and animals.

Many of our invasive species have hitched a ride into this county, but many were brought here because they have a valuable use. Take Johnsongrass for example. Johnsongrass has been used for forage and to stop erosion, but it is often considered a weed for the following reasons: 1. Foliage that becomes wilted from frost or hot dry weather can contain sufficient amounts of hydrogen cyanide to kill cattle and horses if it is eaten in quantity. 2. The foliage can cause 'bloat' in such herbivores from the accumulation of excessive nitrates; otherwise, it is edible; and 3. It grows and spreads so quickly that it can 'choke out' other cash crops that have been planted by farmers.

Kudzu is another invasive species that has been introduced into the United States. It has many good qualities such as soil improvement and preservation, animal feed, basketry, medicine, and food uses. In fact, while I was an agricultural student, I wrote a paper about using kudzu as food for livestock. There is just one problem. It can take over forests and can kill trees and other vegetation. In the Southern states, it is very common to see the damages caused by kudzu. It is very difficult to control, but the USDA is working on disease organisms that will not kill other plants.

Earlier this year, I visited an international market in Memphis and I purchased Chinese yams. They look similar to sweet potatoes but they are completely different. These were steamed and smashed and eaten. They were sweet and were worth the effort of preparing them. Since I was unfamiliar with this species, I looked up information on the internet and discovered that they have many food and medicinal uses. In Chinese medicine, they are used to support the female endocrine system and are used for type 2 diabetes. It is also used to reduce blood lipids.

So I got to thinking, if this plant has all of these beneficial properties, will it grow this far north. It didn?t take long to find the Missouri Department of Conservation website which strongly discouraged people from growing it. It is described as ?an aggressive vine, forming small bulbils that resemble little potatoes in the axils of its leaves. New vines quickly sprout from these bulbils, which typically drop off the vine and can be easily carried to new locations by water or rodents or in topsoil moved for construction purposes.? The Missouri Botanical Garden has a map that shows that the nearest confirmed location to us is in Stoddard County.

Insects are also included in the species that have been brought into the United States. For example, we are in the maintenance phase of the Missouri boll weevil Eradication program. This key pest in cotton throughout the cotton belt is nearly eradicated from the United States. When it was no longer considered to be an economic pest in Missouri, an economic study by the FAPRI group at the University of Missouri in Columbia showed a five dollar return on investment for every dollar spent by Missouri cotton producers.

We have all heard about the Africanized honey bees that are often referred to as killer bees. They are more aggressive than the European bees but they have not caused the problems to humans in most areas that they have invaded. They have made their way into Arkansas but have not been much of a concern.

The Asian long-horned beetle was first discovered in the United States in Brooklyn, New York, in Aug 1996 and in was later detected in Chicago, Illinois, in Jul 1998. Although this invasive species can attack trees, it has been successfully eradicated from several of these areas.

The emerald ash borer has been found in Wayne County and this area is now in quarantine. It was accidentally brought into the U.S. by a cargo ship from Asia. There is an aggressive campaign to stop the movement of this pest by trapping and by not moving firewood. The U.S. Park Service decided to remove the ash trees from the grounds of the Gateway Arch in St. Louis.

For a brief time in Kennett, we had an infestation of the red imported fire ant. It is likely that the plants were brought her from Memphis following the ice storm. Although we found the alate or winged forms it does not appear that they spread. This is the reproductive stage and if they had not been discovered, we might have fire ants in this area. There are areas in Tennessee and Arkansas where this pest is quite prevalent. They can destroy an ecosystem. In the United States they cause problems to the electrical grid, agriculture, and the stings to humans and animals.

A new insect pest that has potential problems in Southeast Missouri is the brown marmorated stink bug. This insect was first collected in 1998 in Allentown, Pennsylvania, but probably arrived several years earlier.it is thought to have arrived in shipping crates from Asia. This invasive pest has been found in a Kansas rest stop west of Kansas City, Kansas. To the best of my knowledge, it has not been found in Missouri yet.

While some of the non-native invasive plant species were brought into the United States for good purposes, once they escaped into natural ecosystems, they began causing problems. Hopefully we won?t have any new species showing up anytime soon.

University of Missouri Extension programs are open to all.

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