BLACKVILLE – They have been coming to our shores uninvited for centuries.

Plants, animals, insects and diseases from other countries have traveled to North America by many means – sometimes on purpose and sometimes by accident. Now Southern forests are being threatened by several nonnative species, and authorities are asking the public’s help to locate and eradicate these destructive pests.

A short course held Wednesday at Edisto Research and Experiment Station in Blackville gave landowners, industry representatives and others who work with forested areas information on identifying and controlling six of the top insects and diseases. Redbay wilt disease and more than 15 of the most invasive plants that threaten forests were discussed.

Kathy Ellington with Clemson University Plant Industry Regulations covered the Sirex woodwasp, the Emerald ash borer and the Asian long-horned beetle.

“The female Sirex woodwasp injects a fungus in both stressed and healthy pines which kills them,” Ellington said. “They have been found as far south as Pennsylvania so far.”

An infestation of the Sirex woodwasp can result in an 80 percent mortality rate in a pine stand, Ellington said. A parasitic nematode is being used to help control the nonnative wasp. The insect is thought to have been introduced in solid wood packing material at ports.

The Emerald ash borer is an exotic beetle from Asia first discovered in the United States in 2002 in Michigan. Though it has only been seen in the Great Lakes region so far, Ellington said the potential for it spreading to the Southeast is a real threat.

“This is one of the pests that has been spread by people moving firewood from one place to another,” Ellington said.

The larvae feed in the cambium between the bark and the wood of ash trees, producing galleries that can eventually girdle and kill branches and entire trees. Canopy dieback and damage from woodpeckers feeding on the insect eventually lead to the death of the tree. D-shaped exit holes are seen along the trunk where adult beetles emerge.

Hardwoods in New York and some surrounding states are being attacked by the larvae of the Asian longhorn beetle. Species of maple, sycamore, birch, elm, poplar and willow have been known to be affected so far. This is another pest that is thought to have arrived in the U.S. in wood packing material.

Stephen Fraedrich, research plant pathologist with USDA Forest Service, shared the latest information on redbay wilt disease. In 2005 the redbay ambrosia beetle and its associated fungus was found to be linked with the rapid death of redbay and sassafras populations in coastal South Carolina, Georgia and across Florida. Infected redbays wilt and die within a matter of weeks or months.

“A lot of scientists and state agencies are working on this,” Fraedrich said. “The beetle is so small it is hard to detect.”

Infected trees first brown at the top, and then the foliage losses vigor and droops, Fraedrich said. Death occurs rapidly. Trees that have died should be chipped and burned on site to prevent spreading the beetles, Fraedrich said.

Beech bark disease, transmitted by a nonnative species of beech scale, has been causing significant problems in various areas of the United States and Canada including parts of the Great Smoky Mountains National Park. No signs of the scale or fungus have been found in South Carolina yet, but Steve Oaks of the USDA said it merits keeping a close watch over.

“Compared to the redbay problem, beech bark disease is glacier-like,” Oaks said.

Sudden oak death, which is caused by a newly identified fungus, Phytophthora ramorum, was found in southern California in the 1990s. It has the potential to infect oaks and other trees and shrubs elsewhere in the U.S.

“As of today,” Oaks said, “the killing of oaks has been limited to California and Oregon.”

Camellias from California nurseries shipped to South Carolina in 2003 and 2004 were found to have the pathogen that causes sudden oak death, he said. From those infected plants, it has not moved into the surrounding environment.

Three other Eastern oak disorders resemble sudden oak death including oak wilt, oak decline and red oak borer infestation.

Jonathan Smith with BASF and Travis Rogers with Dow Agro Science gave information on the identification and control of nonnative invasive plants.

“Invasive species exhibit rapid growth, early maturation, prolific seed production, rapid vegetative growth, have no major pests and have effective dispersal means,” Rogers said.

He emphasized the need for concern, noting that it costs U.S. agriculture $138 billion per year to fight invasive plants.

“There are over 30,000 introduced species that are invasive,” Rogers said. “Control methods are fragmented, piecemeal and under-funded.”

Smith and Rogers reviewed the identification, history, method of spread and suggested methods of control for trees, shrubs, vines, grasses, sedges and herbs that are classified as a severe threat by the South Carolina Exotic Pest Plant Council. These species are known to pose a severe threat to the composition, structure or function of natural areas in the state.

Beth Richardson, Clemson Extension Service, ran through a brief summary of tree pathogens and agents of blue stain and their bark beetle associates including slides showing the symptoms of affected trees.

What do you do if you suspect you have an infestation of a nonnative invasive species?

Mary Douglas, USDA, explained the purpose of the Animal and Plant Health Inspection Service and of Plant Protection and Quarantine.

“Our mission is to safeguard U.S. agriculture and natural recourses,” Douglas said. “It is our job to keep foreign plants out of the U.S., to document the presence or absence of plant pests in the U.S. and to detect, control and eradicate pests.”

Douglas said that as of September 2005, all wood packing material entering the U.S. must be heat treated or fumigated with methyl bromide to help prevent the introduction of pests.

Gypsy moths and fire ants are two pests that her agency has been working to eradicate, Douglas said. The cost of eradication of invasive pests is usually shared by the state, federal and local governments, she said.

For more information on any of these or other forest management problems, contact the local Clemson University Extension office.

To order a copy of “Nonnative Invasive Plants of Southern Forests,” a field guide for identification and control by James H. Miller, write to Southern Research Station, P.O. Box 2680, Asheville, NC 28802. You may also e-mail a request to pubrequest@srs.fs.gov or call 828-257-4830.

T&D Correspondent Minnie Miller can be reached by writing to her at 138 Nature’s Trail, Bamberg, SC 29003. Discuss this and other stories online at TheTandD.com.

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