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HomeMy WebLinkAbout2012 03 12 Informational 102 Providing information regarding Laurel Wilt Disease on local treesCOMMISSION AGENDA ITEM 102 March 12, 2012 Regular Meeting Informational X Consent Public Hearings Regular KS City Manager SR Department REQUEST: The Community Development Department, Arbor Division, is providing information to the City Commission on the laurel wilt disease affecting local trees. SYNOPSIS: Laurel wilt is a vascular disease that affects members of the Lauraceae family. In Winter Springs, this includes bay trees ( Persea species), camphor, and avocado. CONSIDERATIONS: Laurel wilt is a vascular disease of the Lauraceae plant family. The disease is caused by a fungus that is transmitted by the non - native redbay ambrosia beetle. Presently, it is estimated that millions of Persea species have died from the disease throughout their native range of North Carolina to south Florida and west to Mississippi. Trees from the Lauraceae family present in Florida that could be affected by the disease include redbay, swampbay, silkbay, sassafras, northern spicebush, pondberry, pondspice, avocado and camphor. Once a tree becomes inoculated with the laurel wilt fungus, it typically dies within a few weeks up to a few months. The infected tree then continues to serve as a breeding ground for the beetle. When the infected trees die, they are often removed and transported offsite, thereby transmitting the beetles throughout the state and potentially across state lines. Since the disease also affects avocado trees, it has the potential to harm both the Florida and California avocado industry. Bay trees comprise a very small portion of the urban canopy of Winter Springs, therefore laurel wilt is not likely have a large visual impact on the City's canopy. Although there are a fair amount of camphor trees in wooded areas in the City and in residential yards, the Informational 102 PAGE 1 OF 2 - March 12, 2012 camphor is an invasive tree species and removal of these trees is recommended. Avocados are an ornamental fruit tree and are likely to be confined to residential yards. The other trees affected in Florida, such as sassafras and pondspice or not common in this area. With that said, it is important to educate the residents of Winter Springs about laurel wilt and the risk of spreading the disease. A study conducted by the University of Florida found that chipping the trees and covering them with a tarp for at least one week is a good disease management strategy. Some beetles were found to have survived the chipping process, so covering the wood chips for at least a week is important to reduce the spread of the beetle. Since laurel wilt fungus was not found to be present in the wood chips, using the chips as mulch does not pose a threat to other living trees in the Lauraceae family. FISCAL IMPACT: There is no know fiscal impact related to this agenda item. COMMUNICATION EFFORTS: This Agenda Item has been electronically forwarded to the Mayor and City Commission, City Manager, City Attorney /Staff, and is available on the City's Website, LaserFiche, and the City's Server. Additionally, portions of this Agenda Item are typed verbatim on the respective Meeting Agenda which has also been electronically forwarded to the individuals noted above, and which is also available on the City's Website, LaserFiche, and the City's Server; has been sent to applicable City Staff, Media /Press Representatives who have requested Agendas /Agenda Item information, Homeowner's Associations /Representatives on file with the City, and all individuals who have requested such information. This information has also been posted outside City Hall, posted inside City Hall with additional copies available for the General Public, and posted at five (5) different locations around the City. Furthermore, this information is also available to any individual requestors. City Staff is always willing to discuss this Agenda Item or any Agenda Item with any interested individuals. Additional information on Laurel wilt will be published in an upcoming edition of the City's Newsletter. RECOMMENDATION: Staff requests the City Commission receive and review the information provided in this Agenda Item. ATTACHMENTS: A) University of Florida - Laurel Wilt Publication (FOR289) Informational 102 PAGE 2 OF 2 - March 12, 2012 UF FLORIDA IFAS Extension FOR289 Assessing the Survival of the Redbay Ambrosia Beetle and Laurel Wilt Pathogen in Wood Chips' Don Spence, Jason Smith, Albert Mayfield III, Jiri Huler, Randy Ploetz and Lukasz Stelinski Laurel wilt (LW) is a vascular disease of the Lauraceae plant family. The disease is caused by a fungus (Raffaelea lauricola T. C. Harrin., Aghayeva, & Fraedrich) that is vectored by a non - native beetle, the redbay ambrosia beetle (RAB), Xyleborus glabratus Eichhoff (Coleoptera: Curculionidae) (Hanula 2008). To date, it is likely that millions of Persea species have died from the disease, which currently ranges from North Carolina to south Florida and west to Missis- sippi. In this study we examined the survivability of the RAB and the laurel wilt fungus in wood chips made from infested trees and chipped using a standard tree chipper. With large volumes of wood from dead Persea species, the potential for intact infested logs to be moved from state to state is significant. This disease also affects avocado ( Persea americana) and has the potential to harm both the Florida and California avocado industry. Results suggest that chipping wood can be used to minimize the spread of both RAB and the laurel wilt fungus. Introduction The laurel wilt vector and pathogen were introduced into Georgia before 2002. Since then, laurel wilt has killed plants in the Lauraceae, including: redbay (P. borbonia), swamp- bay (P. palustris), silkbay (P. humilis), sassafras (Sassafras albidum), northern spicebush (Lindera benzoin), pondberry (Lindera melissifolia), and pondspice (Litsea aestivalis) (Fraedrich et al. 2008). The disease also affects planted avocado (P. americana) and camphor (Cinnamomum camphora) (Mayfield et al. 2008, Smith et al. 2009). In the eight years since laurel wilt has been recognized in the U.S., it has spread faster to the South than it has to the North or West (Figure 1). From the site of first detection, the disease has traveled some 200 miles north, reaching North Carolina in 2011. To the south, the disease has moved almost twice as far, reaching Miami -Dade County, Florida, in 2011 (DPI 2010). Laurel wilt was confirmed in Bay County, Florida, and Mississippi in 2009 and in Alabama in 2011; however, it is suspected that these movements were due to the anthropogenic movement of firewood (Riggins et al. 2010) ( Figure 1) . In its native Asian range, RAB is not known to be a pest. The RAB is a true ambrosia beetle and attacks both living and dead trees. And, like other ambrosia beetles, it bores into a tree and deposits spores of its symbiotic fungi on which it feeds (Harrington 2008). When living host trees are attacked, the laurel wilt pathogen (R. lauricola) spreads inside the tree through the water - conducting xylem tissue. Although the exact mechanism of mortality is not known, tree death likely occurs due to dysfunction of the water conducting cells. Once a susceptible host is inoculated with the fungus, death can occur in a few weeks or up to 1. This document is FOR289, one of a series of the School of Forest Resources and Conservation Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date November 2011. Visit the EDIS website at http: / /edis.ifas.ufl. edu. 2. Don Spence, PhD student, Department of Plant Pathology, University of Florida, Gainesville, FL 32611; Jason Smith, assistant professor, School of Forest Resources and Conservation, University of Florida, Gainesville, FL 32611; Albert Mayfield III, USDA Forest Service, Southern Research Station, Asheville, NC 28806; Jiri Huler, Department of Biology, North Carolina State University, Raleigh, NC 27695; Randy Ploetz, University of Florida Tropical Research and Education Center, Homestead, FL 33031; and Lukasz Stelinski, University of Florida Citrus Research and Education Center, Lake Alfred, FL 33850. The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non - discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A &M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Millie Ferrer - Chancy, Interim Dean several months. Once trees die, they continue to serve as breeding sites for more RAB. New RAB populations can be established by a single female through a unique reproductive strategy. A female RAB can produce flightless male offspring without mating, and upon mating with those offspring males, she can produce additional females that can fly to new trees. Thus, a single female beetle emerging from a tree has the potential to start a new population. V" 09kow 49 :• M" pal W W MW91* GA 2007 2008 toao 2011 Mror -atmM prowdrd ey: C-h4p BLXM A" Fickw9ri eb3ta•��grc.s#aR�•g0.YrF � �IqY- Er e� ►,�r�t�,fr *lhrlon►rJawsd.��pin L.wrw Rid jr John J_ f MnLms IreSdVV trrr'"MO.SCAS �- piq �n gern m lappr,+�fx�rbt.ad„ Rt4 frKkrr 4gfi3 MCf#eywoldir Wmes. rob.1nch rcdgr_g*V [xinaticRapr►�1d"F #4hli�If .a�abaRna.gou > >e 7a u¢ to M Y__5 "w„ IoMw '.Wtw t2,201 I Figure 1. Counties where Laurel Wilt has been identified. Credits: USDA Forest Service, Forest Health Protection, http: / /www. fs. fed. us /r8 /foresthealth /laurelwilt /maps /region al_infestation_ map_ april_14_2011.jpg to view full sized map. Dead trees in urban landscapes are commonly taken in large sections or chipped into wood pieces and taken to local landfills. On occasion, when large volumes of trees are collected from urban or rural areas they could be taken to a wood processing plant for conversion into wood chips that can be used as mulch or burned for electricity generation (Asikainen and Pulkkinen. 1998). Due to the concern about transmission of LW in chipped wood, we explored the potential elimination and neutralization of the RAB and laurel wilt fungus through the conversion of infested trees into small wood chips. Study Several dozen diseased redbay trees were collected and chipped into small wood pieces, ranging from 6.3 to 40 cm A Bandit model 1890 tree chipper was used to chip the trees into 1 m mulch bins; the bins were either exposed to full sun or kept in constant shade. In each bin we placed small mesh bags containing woodchips from the infested redbay trees (Figure 2). The bags were extracted every two weeks and tested for the presence of the laurel wilt fungus by plating small pieces of wood on artificial growth media ( Figure 3) . The remaining wood chips from each mesh bag were placed into small insect rearing chambers and monitored for 10 weeks for beetle emergence (Figure 4). The rearing chambers were kept at room temperature and exposed to light daily. I To further test RAB survival in chipped wood, we placed ten piles of infested redbay wood chips from the pre - chipped wood pile under mesh netting in a garage to evaluate RAB emergence without being exposed to rainfall or high temperatures from direct exposure to sunlight (Figure 5). We also placed ten 50 cm logs from the pre- chipped wood pile (infested with RAB) under mesh netting in the same garage to collect any beetles that emerged from intact pieces of wood (Figure 6). Over the course of the study, temperature was recorded in the wood chip bins for each treatment. A temperature Figure 2. 1 m mulch bin with mesh bags on the surface. Figure 3. Wood chips with black staining from laurel wilt. Figure 4. The rearing chambers were kept at room temperature and exposed to light daily. Figure 5. Wood chips under a mesh net. probe was placed in the center of each bin and data logged every hour from the beginning of the study in July until its termination in late October. Results Raffaelea lauricola was not recovered from any of the 1400 samples of plated wood chips from the mesh bags. No RAB emerged from any of the 400 insect rearing chambers, regardless of whether the wood chips were in the sun or shade. Five RAB emerged from the ten netted wood chip piles (Figure 6). This is in contrast to 856 RAB that emerged from 10 netted redbay logs (Figure 7) that were monitored over the same period. Recommendations For those who wish to dispose of their dead redbay trees that were killed by laurel wilt, chipping the trees and covering them with a tarp for at least one week is a very good disease management strategy. Since some RAB did survive the chipping, tarping the wood chips for at least a week is an important component to reducing the poten- tial spread of the beetle. This type of sanitation strategy could help to reduce the local impact of the disease. • Since the laurel wilt fungus was not recovered from wood chips, the use of wood chips as mulch (after the chips have been tarped for a week) does not pose a threat to living trees in the Lauraceae, nor does it provide a mechanism for the movement of the laurel wilt disease. Conclusion Chipping trees that died from laurel wilt is a useful tool to minimize the potential spread of laurel wilt. This study provides evidence that: 1) owners of dead redbay trees have a simple technique to dispose of dead trees; 2) chipping dead trees can contain the disease within a small area; and 3) there is a low probability of long- distance movement of LW via wood chips. More research is planned to assess the environmental limits of X. glabratus and R. lauricola. 3 Figure 6. 50 cm log infested with RAB under a mesh net. References Asikainen, A., and P. Pulkkinen. 1998. Comminution of logging residues with evolution 910R chipper, MOHA chipper truck, and Morbark 1200 tub grinder. Int. J. For. Engl. 9: 47 -53. (FDACS) Florida Department of Agriculture http://fresh- fromflorida.com/press/2011/0225201 I.html Fraedrich, S., T. Harrington, R. Rabaglia, M. Ulyshen, A. Mayfield, L. Hanula, J. Eickwort, and D. Miller. 2008. A Fungal Symbiont of the Redbay Ambrosia Beetle Causes a Lethal Wilt in Redbay and Other Lauraceae in the South- eastern United States Plant Disease 92: 215 -224. Hanula, J. L., A. E. Mayfield, S. W. Fraedrich, and R. J. Rabaglia. 2008 Biology and host associations of redbay ambrosia beetle (Coleoptera: Curculionidae:Scholytinae), exotic vector of laurel wilt killing redbay trees in the south- eastern United States. Forest Entomology 101: 1276 -1286. Harrington, T., S. Fraedrich and D. Aghayeva. 2008. Raffaelea lauricola, a new ambrosia beetle symbiont and pathogen on the Lauraceae. Mycotaxon, 104: 399 -404. Mayfield, A. E. III, J. A. Smith, M. Hughes, and T. J. Dreaden. 2008. First report of laurel wilt disease caused by Raffaelea lauricola on avocado in Florida. Plant Disease 92: 976. Riggins, J. J., M. Hughes, J. A. Smith, A. E. Mayfield, III, B. Layton, C. Balbalian, and R. Campbell. 2010. First Occurrence of Laurel Wilt Disease Caused by Raffaelea lauricola on Redbay Trees in Mississippi. Plant Disease 94: (5) 634 -634. Smith, J. A., L. Mount, A. E. Mayfield III, C. A. Bates, W. A. Lamborn, and S. W. Fraedrich. 2009b. First report of laurel wilt disease caused by Raffaelea lauricola on camphor in Florida and Georgia. Plant Disease 93: 198. USDA Forest Service, Forest Health Protection http: / /www fs. fed. us /foresthealth/ ►1