SAF told laurel wilt seen on east coast, on move By Ray Newbold Jim Meeker, entomologist with the USDA Forest Service unit in Pineville, Louisiana, reported to the Louisiana Society of American Foresters (LASAF) Executive Committee the good news that there are currently no active southern pine beetle infestations known to be present in the State of Louisiana. However, another danger emanating from the east coast may be at our door-laurel wilt. Trees in the laurel botanical family are susceptible to this pathogen. The predominant species at risk in the U.S. are redbay which is widely distributed from VA to TX, and sassafras which is common to virtually all of the eastern United States except in the most northerly reaches. The disease is spread by the redbay ambrosia beetle. This insect was first detected in 2002 in traps near Port Wentworth, Georgia. In 2003, significant redbay mortality on Hilton Head Island, South Carolina was reported to the South Carolina Forestry Commission. Although drought and water-table fluctuations were initially suspected as the cause, staff eventually found the redbay ambrosia beetle and an unknown wilt fungus in redbay trees on Hilton Head. By 2004, the Georgia Forestry Commission was also receiving reports of redbay mortality in coastal areas. The fungus was isolated from the redbay ambrosia beetles, which indicated that the beetles were vectoring (carrying) the fungus into the trees when they attacked. By early 2005, the beetle and fungus combination was confirmed as the cause of redbay mortality. Advancing from coastal counties, the disease spread to more inland counties in South Carolina, Georgia, and Florida. In early 2007, a symposium was held to share what was known about the beetle and fungus and to strategize the forest health community's next steps. In July 2009 the Mississippi Department of Agriculture and Commerce and the Mississippi Forestry Commission confirmed the positive identification of laurel wilt disease in Jackson County, where the disease was discovered killing redbay trees. This was the first known occurrence of laurel wilt in Mississippi, and the most western known infection to date. Research is currently underway to determine adequate control measures. Symptoms of a laurel wilt infestation include drooping foliage with a reddish or purplish discoloration. Removal of tree bark reveals a black discoloration in the outer sapwood, and evidence of ambrosia beetle boring can be seen in the tree stem. Reports of redbay and sassafras tree deaths in your area should be made to the local office of your State Forestry Commission or a USDA Forest Service, Forest Health Protection unit. Introduced to the U.S. from Asia, it was initially believed that the redbay ambrosia beetles had come directly from solid-wood packing materials. The disease is not known to spread apart from these beetles transmitting the fungus, but may disperse naturally through beetle flight, or can spread through the transport of infested host material, such as firewood, logs, and infested plants. The LASAF has recently adopted a position statement on the restriction of firewood movement onto state lands. That position reads as follows: "A number of states have already adopted strict regulations on commercial firewood marketing within their borders. The Louisiana Society of American Foresters urges the adoption of such regulations by the Louisiana Legislature. Additionally, it supports restrictions on firewood movement by private citizens in the state into campgrounds on state lands. These controls should be coupled with a strong outreach and educational program to explain the reasons for their enactment." The rapid spread of laurel wilt emphasizes the importance of this action and the risk of delay. |