Jarman's Weekly Agronomy News

December 27, 2000

Alien Pests are Invading Missouri

Last year, I was asked to present a local program on pests for the next   century. This year several people from the University of Missouri put on a presentation on a similar theme. Knowing about this ahead of time, I wondered if the two lists would be similar. They would have a year ahead of foresight. But since this fox was doing the counting, I was sure there would be a chicken dinner waiting. Here is the article on their take of the invading pests and next week I will give mine.

There are a host of alien invaders threatening the U.S as well as Missouri. Named were five weed species, six insect species and three pathogens that pose a threat in Missouri. We're calling them 'the New Invaders'. Some are newer than others and some are back after extended absences.

Leafy spurge, a major problem in pastures and rights-of-way in many western states, was first documented in Missouri about 50 years ago. It was eradicated, then reappeared in Northwest Missouri. Cattle will avoid grazing on land with leafy spurge infestation as low as 10 percent. The plant's extensive root systems and explosive seed capsules, which project seed as far as 15 feet, make this perennial weed a potentially serious problem.

Kudzu, an Asian vine that was brought to the United States for soil erosion control, has long been a plague in forests and rights-of-way in southern states. It's an aggressive perennial vine that overgrows everything. It can grow up to a foot a day. It's spreading further north now. Kudzu has been reported in central Missouri and as far north as Ralls County.

Another Asian plant once used for erosion control is Sericea lespedeza. Seen in Missouri since the late 1930s, this legume is a problem in pastures and rights-of-way. Japanese hops, is similar to kudzu in that it's an aggressive vine, has recently been reported infesting rights-of-way, pastures, cropland and golf courses in several Missouri counties. Cutleaf teasel, a plant native to Europe that probably spread through its use as dried arrangements in cemeteries, has taken over many rights-of-way.

Bacterial leaf scorch, long a disease of hardwood trees in the eastern and southern United States, was detected this fall in pin oaks in central and eastern Missouri. Although it can kill a large tree in five to 10 years, with early detection and pruning you can stop the spread within the tree.

Plum pox virus, which has already severely damaged the European stone fruit industry, was reported in fruit trees in Pennsylvania in 1999. Spread by aphids and through nursery stock, its symptoms include premature fruit drop, barren trees and split bark. The worst symptom is the blotched, necrotic fruit. Although the virus has not yet shown up in Missouri, it takes three years before it shows any symptoms.

Foliar nematodes are microscopic worms that attack ornamental plants, especially hostas. These have only started up here in the last few years. Because the nematodes are spread through splashing water, methods of minimizing the impact include adequate plant spacing, sanitation and no overhead watering.

The Chinese soybean aphid was first confirmed in northern Missouri and several other Midwestern states this year. It's a major pest in China. It's been shown to reduce yields by up to 30 percent. In Asia, it overwinters on buckthorn but we don't know whether it will successfully overwinter here.

The Japanese beetle has been in Missouri since the 1930s, but it has not spread beyond nine counties in the St. Louis area. The larvae don't like to overwinter in our heavy clay soils. We're kind of holding it at the border. The beetle, which has a host range of hundreds of plants, probably can't be held back forever. They're coming, but there are some things we can do to keep them out and slow them down.

Red oak borer, a pest that preys primarily on red, black and scarlet oak, gained a foothold in southern Missouri during the drought of 1999. White oak, which is more prevalent in the Ozarks, appears to have some resistance but can still be susceptible if the tree is weakened. This is an insect that attacks stressed plants. The red oak borer has killed trees at "an alarming rate" in northern Arkansas during the last two years. In severe infestations, "it can take out up to 40 percent of the timber value."

The Asian longhorn beetle, another danger to hardwood trees, was accidentally introduced to the eastern United States in the mid-1990s. It has decimated hardwood forests in its native China and has become the target of serious eradication efforts in several large U.S. cities. It has not yet been reported in Missouri.

The Gypsy moth has been spreading westward toward Missouri at the rate of about 15 miles per year. Anastasia Becker, an MU Extension associate who works closely with the Missouri Department of Agriculture to monitor and control the moth, reported only 13 were trapped in the St. Louis area this year. They also found one down in Taney County, but only one. The good news is there's not really a hot spot. St. Louis and Taney Counties have been hot spots several times in the past.

A South American native, the red imported fire ant, is established in 10 southeastern states and appears to be "here to stay. They're very aggressive ants. They tend to take over from the native ants. Red fire ant mounds were found for the first time in the St. Louis area in 2000. They could become a problem in the next few years. Their painful stings can interfere with grazing and crop harvesting.  The bites can easily be infected, and it can really hurt the young calves.

O'Day, Starbuck and others will expand on the topic of new invaders at the MU Pesticide Applicator Training (PAT) programs, scheduled for Jan. 17-19, 2001, at the Ramada Inn in Columbia. For more information or to register for the program, call (573) 882-8320

The sources for this article from the University of Missouri-College of Agriculture Food and Natural Resources (MU CAFNR) are Maureen O'Day, Extension Associate-Integrated Pest Management (573) 882-3786; Anastasia Becker, Senior Research Specialist-Integrated Pest Management Chris Starbuck, Associate Professor-Horticulture (573) 882-9630; Fred Fishel, Extension Assistant Professor-Integrated Pest Management (573) 884-6361.

Attention: Growers of certified organic grain crops may be interested in Clarkson Grain Company's request for grains to be used for food or feed products. An information packet is available from the Callaway County MU Extension Center or contact Lynn Clarkson directly at the Clarkson Grain Company, Inc., 320 East South, Cerro Gordo, IL 61818 Telephone 1 800 252-1638, or 1 217 763-2861, Fax 217 763-2111, E-mail: cgci@one-eleven.net URL: www.clarksongrain.com. Clarkson Grain is also interested in booking production acres for the 2001 growing season.

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	Jim Jarman, jarmanj@missouri.edu Agronomy Specialist, (573) 642-0755 Site maintained by: Jen Pauley, pauleyj@missouri.edu Last update: 04/27/06