A Destructive Duo in the Southeast and a Potential Threat to California. Don Duerr USDA Forest Service Forest Health Protection Atlanta, Georgia

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1 A Destructive Duo in the Southeast and a Potential Threat to California Don Duerr USDA Forest Service Forest Health Protection Atlanta, Georgia

2 Brief History 2002, Savannah, Georgia: USFS Early Detection & Rapid Response Program for Exotic Bark Beetles trap captures Xyleborus glabratus for the first time in North America

3 Brief History This ambrosia beetle is native to Asia (Japan, Myanmar, Taiwan, etc.). Assumed to have entered the U.S. in solidwood packing material. Delimiting traps at Port Wentworth, GA did not capture additional X. glabratus.

4 Brief History In 2003, redbay (Persea borbonia) mortality was reported on Hilton Head Island, South Carolina; initially thought to be drought stress. In 2004, similar redbay mortality was reported from coastal Georgia. By early 2005, X. glabratus and a fungus it vectors were confirmed as the cause. The wilt fungus was tentatively identified as a species of Ophiostoma, and was further identified as an unknown Raffaelea species (lauricola). Common names were given: redbay ambrosia beetle (RAB) and laurel wilt.

5 Brief History Based on FS supported surveys in , the extent of establishment was such that eradication was deemed impossible. The beetle has continued to spread at a rate of about 20 miles per year (more via humanaided dispersal). Currently, about 65 coastal plain counties in AL, FL, GA, MS, and SC are infested. Redbay mortality in the % range. Two main threats to CA: avocado and California bay laurel (both susceptible in lab)

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7 Xyleborus glabratus (RAB) A very small ambrosia beetle (2 mm long) Has been recorded from India, Bangladesh, Taiwan, Japan, and Myanmar. Reported host plants in Asia include species in Lauraceae, Dipterocarpaceae, Fagaceae, and Fabaceae. Not injurious in Asia. The laurel wilt fungus is not known to occur in these or other plant species in Asia. Here, only found in Lauraceae (so far).

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11 Arrows point to mycangea, where the beetles carry spores.

12 Raffaelea lauricola (No magnification)

13 Raffaelea lauricola Conidia under high magnification

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21 Redbay: What s Being Lost? Evergreen tree that can grow to 60, tall 2.5 DBH Limited use as a wood material, but the fine grained wood is useful for cabinets, veneer, and boat trim Fruits are consumed by a wide variety of birds, rodents, deer, and bears. The fruits persist into winter, making it an important winter food source Redbay is the primary and most important host for larval Palamedes swallowtail butterflies Dried redbay leaves have been used for generations as the real Southern bay leaf for flavoring savory foods considered essential for gumbo Ceremonial and medicinal uses to Native Americans

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24 Sassafras (Sassafras albidum)

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27 (federally listed endangered species)

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31 Commercial crop earns about $30 million/year and supports 300 full time jobs Commercially grown on about 8,000 acres About 60,000 residents have at least one tree

32 Avocado Susceptibility More susceptible to fungus: Brogdon Miguel Donnie Simmonds Lula Bernecker Monroe Larger trees in general Less susceptible to fungus: Reed Choquette Catalina Florida Hass Winter Mexican Hass Hall Smaller trees in general *All varieties tested to date are attacked by the beetle.

33 Avocado in California CA has the largest avocado industry in the USA Approximately 6,000 growers farming 66,000 acres Annual harvests valued at $ million Hass is the most commonly grown variety Mexico is the world s leading producer of avocados, so the potential threat there is even more dire The Resplendent Quetzál, National Icon of Guatemala, feeds on small wild avocados and fruits of other trees in the Lauraceae family.

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35 California Bay Laurel Common, attractive, aromatic evergreen shrub/tree Can grow to 30 meters in height, 30+ DBH Frequent ornamental/landscape tree Ranges from San Diego to southern Oregon and into foothills of Sierra Nevada Mtns; sea level 1600 Edible fruits: roasted California bay nuts Leaves can be used in cooking, but are very strong Backs and sides of acoustic guitars, spoons, bowls Medicinal uses: cure for headache, toothache, earache Leaves under the mattress will keep fleas away! Primary foliar host for Sudden Oak Death

36 Recovery & Mitigation Slow the long distance, human assisted spread of the disease. Improve our understanding of the biology, host associations, and impacts of the disease and its vector. Protect individual, high value landscape trees with pesticides when feasible. Develop other tools for management of the disease and its vector, possibly to include sanitation, other silvicultural methods, trap out or attract and kill techniques, use of resistant genotypes, and biological control. Assess the need for, and possibly pursue, a germplasm conservation program for threatened hosts. Continue to monitor the geographic spread of the disease, assess its impacts on host species as its spreads to new ecosystems, and educate the public about the issue.

37 What Have We Done and Tried So Far? Tried to convince regulatory agencies to pursue a quarantine on redbay plants, chips, and firewood; they were not convinced Cutting and removing infested trees and a strip of uninfested trees on Jekyll Island, GA (didn t work) Found that Manuka oil and Phoebe oil are good lures for the beetle (used with funnel traps) Injecting propiconazole (Alamo) fungicide does work, but it is expensive, labor intensive, not sure about rate of uptake or duration of efficacy Using PentraBark to try to get Alamo absorbed directly through bark has not worked so far

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39 Germplasm (Seed) Conservation Redbay seeds collected, then stored at the National Seed Laboratory in Macon, Georgia

40 Resistance Study FS funded study at UF into potential redbay resistance Identify living redbay in areas with 95+% mortality Cuttings taken from live trees for vegetative propagation Putatively resistant redbays can be vegetatively propagated Resistant redbay clones planted in plots for field testing (ongoing effort) So far, most of the resistant clones are susceptible in the lab, but differences appear to exist in the field

41 80 different clones propagated so far

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44 Also Organized two well attended conferences (Jekyll Island, GA in 2007 and Savannah, GA in 2009) Inoculation studies on a wide variety of tree species (oaks, maples, etc.); so far, only Lauraceae is susceptible to the wilt fungus Plant community change studies: oak, juniper, holly, palmetto, wax myrtle, loblolly pine, and Vaccinium are more abundant following redbay mortality

45 For More Information: The Region 8 Forest Health Protection Laurel Wilt Website:

46 CONTACT: DON DUERR USFS FOREST HEALTH PROTECTION 1720 Peachtree Road, NW, Atlanta, GA (404) or (404)