Georgia, along with all of the southern states, is vulnerable to exotic insects, diseases and plants. Dutch elm disease was found in Atlanta, Georgia in 1967 and since then has virtually destroyed the American elm and other native elm species in the State. The chestnut blight introduced from Europe has devastated the American chestnut in the Southern Appalachian Mountains. Three separate introductions of the gypsy moth have appeared in Georgia since 1991. Kudzu an exotic plant from Asia now occurs in all of Georgia’s 159 counties. Cogon grass and tropical soda apple are two exotic plant species that are currently being eradicated in the southeastern United States (Figure 176).
The GFC in cooperation with various federal agencies maintains a vigil for introduced pests. Each year the GFC places gypsy moth detection traps along roadsides and in recreational areas (Figure 177). The GFC began trapping for gypsy moths in 1973 but it was not until 1986 when a memorandum of understanding was signed between the GFC and the Georgia Department of Agriculture that the GFC began receiving federal dollars to do the trapping. Since that time the GFC and the U. S. Department of Agriculture have systematically grided the state each year in attempts to find any artificial introductions of the pest. To date, the GFC and the USDA Forest Service have eradicated three infestations in three northern counties. In 1991 egg masses of the gypsy moth were found on a river birch tree on the banks of Duke’s Creek in White, County. That find led to the additional discovery of egg masses some two miles away. Ultimately, over 5,250 acres were aerially treated with Bacillus thuringiensis var kurstaki (Bt) in 1991 and 1,937 acres in 1992. The infestation was successfully eradicated in 1993. The second infestation was discovered in Fannin County in 1994 and 1,254 acres were treated in 1995 and 800 acres in 1996 with Bt. Again the treatments were successful in eradicating the moth. Based on interviews with residents, the White and Fannin County infestations were associated with people relocating from Pennsylvania to Georgia. The third infestation was found in Rockdale County in 1994 in a small rock yard. Apparently egg masses were moved into the state via field rock from Pennsylvania. The infestation was monitored for three years by mass trapping, but eventually two acres were treated in 1998 with Dimilin. Again the treatment was successful with complete eradication. Currently, the GFC is concerned about four new exotic pests that threaten the State. These are the Asian longhorned beetle Anoplophora glabripennis, emerald ash borer Agrilus planipennis, sudden oak death fungus Phytophthora ramorum, and hemlock woolly adelgid (pg. 51). The GFC in cooperation with the U.S. Forest Service, USDA APHIS, Georgia Department of Agriculture and the University of Georgia Cooperative Extension Service, is conducting surveys across the State for these pests. The Asian long horned beetle (Figure 178A) has been found in New York and Illinois and eradication efforts in Illinois have been successful. The beetle has killed thousands of maples and other hardwoods since being introduced some 12 years ago. It more than likely came into the U.S. in shipping material known as solid wood packing material (SWPM) that originated in Asia. The GFC has identified over 65 warehouses in Georgia that have been receiving SWPM from Asian markets. The number increases each year. To date, after four years of intensive survey efforts at these warehouses, the GFC has not found any suspect Asian longhorned beetles.
The emerald ash borer (Figure 178B) is another exotic beetle from Asia that kills ash trees. So far it has been found in southeastern Michigan, northern Ohio and Indiana. A small infestation was eradicated in Virginia near the Washington DC area in 2004. Spread has been through the movement of infested nursery trees. Based on surveys conducted in 2003 by the GFC, most of the ash trees sold in Georgia originate from local or southern nurseries thus reducing the risk of having the insect in Georgia. A newly identified foreign pathogen threatens Georgia’s oak woodlands. It is called sudden oak death. The fungus that causes the disease has existed in Europe for many years and was probably introduced into California in the early 1990’s. Tens of thousands of coast live oak, tanoak, and California black oak trees have been killed. This disease could have severe economic and environmental impacts if it reaches Georgia. In March of 2004, plants from Monrovia nursery in California were identified as being infected with the fungus. Georgia nurseries had been receiving thousands of potentially infected plants from Monrovia since January of 2002. In October of 2004 it was learned that two nurseries (Hines and Means in Oregon) had been shipping plants into Georgia that could have been infected with the fungus. The fungus causes leaf spots on many different species of plants (Figure 179A). These plants serve as sources of inoculum that infect trees. On the oak, the disease causes cankers underneath the bark that are characterized by dark zone lines (Figure 179B).
To date, 14 Georgia nurseries have been identi-fied as having received infected plants, but all 14 have been checked recently and certified as free from the fungus. |
Forest Pests: Insects, Diseases & Other Damage Agents |
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