1. Carrie Lapaire Harmon UF/IFAS-SPDN 4-08
Sudden Oak Death and Laurel Wilt: Emerging Plant Pathology Problems of Woody Ornamentals-North and Central Florida
Carrie Lapaire Harmon
UF/IFAS-SPDN
4-08

2. P. ramorum Status
2006, DPI find plants of 5 species of Camellia infected with P. ramorum at 2 nurseries.
2006, Clemson researchers isolate P. r. from water at one of the positive nurseries. Additional sampling has not recovered the pathogen
Florida trace surveys found no additional FL nurseries infected.
Additional hosts of interest: Osmanthus, Prunus, Rosa rugosa, others
2007, DPI finds camellias in a North FL nursery for the second year in a row. The nursery is conducting eradication efforts in tandem with DPI.
An infected plant from this nursery is found in a landscape setting and is eradicated, along with some soil.
While many people heard about sudden oak death/ramorum blight, caused by Phytophthora ramorum, in 2005, there have been detections in the state since then.

3. Environmental Impact
Although there have been positive finds in landscapes, there are no detections currently known to be infected in natural areas.
The pathogen has been isolated from water from a nursery; the pathogen could easily move in our streams, springs, and groundwater.
If this disease were to become established in natural areas, several of our native plant species are listed as possible hosts.
Hosts of concern remain those in nurseries and landscape environments; areas surrounding nurseries are inspected as well.
Although there have been positive finds in landscapes, there are no detections currently known to be infected in natural areas.
The pathogen has been isolated from water from a nursery; the pathogen could easily move in our streams, springs, and groundwater.
If this disease were to become established in natural areas, several of our native plant species are listed as possible hosts.
Hosts of concern remain those in nurseries and landscape environments; areas surrounding nurseries are inspected as well.

4. Phytophthora ramorum: associated symptoms
Two syndromes caused by this pathogen
Leaf and twig blight
Leads to leaf drop and general dieback
Trunk, branch, and bark canker
Disease progresses under the bark, disrupts vascular movement of xylem and phloem – kills the host by clogging up the pathways for movement of water and nutrients – this is why the symptoms include wilting
Cankers occasionally will bleed plant sap – not always

5. Phytophthora ramorum: associated symptoms
Hosts of immediate importance to Florida:
Camellia, azalea exhibit leaf and twig blight
Viburnum also exhibits bark canker (sometimes bleeding) followed by wilt and death

6. What’s FL doing about it?
FDACS, DPI continue to survey nurseries every year
DPI and IFAS are working together to try to identify if there are diseased plants in the FL landscape
Still collecting samples any symptomatic host, especially: camellia, viburnum, rhododendron of CA origin 4 years old or newer exhibiting dieback, leaf blight
Remove a small twig with a few leaves and place it in a zip-top bag. Take the sample to your extension agent and ask them to submit it to GNV.

7. Hosts summary
Many more than 100 species Approximately 2/3 exhibit leaf and stem blight and sporulate
Approximately 1/3 exhibit stem and bole canker and do not sporulate
Complete list in handout
The sporulating hosts are the ones we are very concerned about shipping or receiving shipments of across the country. The oak hosts are apparently a sort of dead end for the pathogen, but the death of mature trees is very disturbing. Hundreds of species and several dozen genera indicate that the pathogen can survice and move in many ways, including on asymptomatic plants and even soil (including the soil of potted plants that may not even be good hosts). The take-home message? Watch for the symptoms, especially in areas near nurseries, and don’t hesitate to submit samples.

8. Ramorum blight: camellia
Camellias may develop leaf spots, leaf blights, and twig and stem dieback

9. Ramorum blight: camellia
Camellias may develop leaf spots, leaf blights, and twig and stem dieback. Other ramorum blight hosts may develop similar symptoms – note the tips of the leaves show the most defined symptoms; this is where water collects (rain, dew, irrigation). Also note the dark margin at the leading edge of the lesions. Other symptoms will include wilting and leaf drop.

10. SOD: oak hosts
Wilt occurs relatively quickly on viburnums. Oak hosts in CA exhibit symptoms that appear sudden, although the disease has been present for a year or more. Symptoms on oak include bleeding cankers and trees that appear to die back suddenly – leaves are often still attached.

11. Contact information
Richard Cullen, Diagnostician
Plant Disease Clinic
Bldg 78 Mowry Rd., University of Florida
Gainesville, FL 32611
Phil Harmon, Extension Pathologist:
UF-IFAS Department of Plant Pathology
1453 Fifield Hall, Gainesville, FL
Insert you regional/local diagnostic clinic information. You may also need to include your state Dept of Ag info.

12. New Disease of Red Bay/Laurel
Host is Persea borbonia, an important species for wildlife
Associated with an exotic ambrosia beetle, Xyleborus glabratus, and caused by a new fungus, Raffaelea laurelensis
Wilted foliage, vascular discoloration, sawdust tubes
Other Lauraceae, including Sassafras albidum, Lindera benzoin, and Persea palustris are killed when artificially inoculated
Coastal locations in FL, GA, and SC
A relatively new invader is killing red bays in three states. Originally detected in Hilton Head, the disease has progressed through coastal areas in three states, including FL. The new beetle, called the Redbay Ambrosia Beetle, was detected in a monitoring trap in 2002 near Port Wentworth, GA. Late in 2003, dying red bay trees were noticed in coastal South Carolina and the beetle was found on the dead and dying red bays and was implicated in the disease spread. Later research has confirmed the fungus, Ophiostoma sp. As the causal agent of the disease, and has detected the presence of the fugus in the beetles, confirming their part in the disease spread.

13. Red bay, Persea borbonia, is a significant component of forest ecosystems in the southeastern US. It has been decimated by laurel wilt.

14. Distribution and Additional Info
Attacks seemingly healthy trees; beetle may be attracted to stressed trees
Leads to wilt and death
Redbay and sassafras mortality in SC, GA and FL
Mortality in Florida since detection increased from 10 to 60% in 9 months
Several Laurel relatives susceptible, including pondspice, avocado, sassafrass, and pondberry/southern spicebush (federally endangered species)
New name is Laurel Wilt Disease
Similar to another devastating tree wilt disease: Dutch Elm Disease

15. FL counties with Laurel Wilt
Duval (2004)
Baker (2006)
Bradford (2006)
Clay (2006)
Nassau (2006)
St. Johns (2006)
Indian River (2006)
Putnam (2007)

16. Wilt, Vascular Discoloration
Brown leaves still attached to branches of a dead/dying tree, closeup A shows discoloration and rot around beetle wounds; closeup B shows a dark ring of vascular discoloration plus a dark rot in the heart wood.

17. Signs of the Beetle
Frass tubes extending from the tree; a sign of ambrosia beetles, Xyleborus glabratus. A closeup of the Redbay Ambrosia beetle itself – notice the light-colored legs and dark, bumpy carapace. Lindgren funnel light traps baited with diseased redbay pieces and 95% ethanol caught Xyleborus glabratus year-round on Ft. George Island, with peak catches in September and November. A similar trap in Hunting Island State Park, SC had a peak in catches in August.
Picture credits: Albert E. Mayfield III, and M. C. Thomas, FDACS/DPI

18. Avocado
Research at the UF-TREC in Homestead and DPI quarantine facilities in GNV has resulted in data on susceptible cultivars of avocado: ‘Brogdon’ was highly, ‘Simmonds’ moderately, and ‘Reed’ slightly susceptible.
In September 2007, the first
landscape avocado plant
succumbed to
the disease in Jacksonville.
‘Simmonds” avocado 20 days after inoculation, DPI

19. What can we do about it?
By the end of 2006, the disease had spread to 5 counties in SC, 15 in Georgia, and 8 in FL
Now there are more than 30 counties with infected trees
Currently, there is no method to halt or even slow the spread of this disease
The beetle is a powerful flier
By the time symptoms appear, the beetle has infected many trees in the area
Pesticide use is not recommended due to the numerous off-target species that would be affected
Biological controls are not known at this time
Human movement of infested plant material is aiding the long-distance spread of the vector.
Two experiments in process: sanitation (cutting out all dead or dying trees) and fungicide/insecticide injections
The speed and efficiency of disease spread via the beetle vector is alarming. One experiment to cut out all diseased/dying redbays in an area was abandoned once it was found that nearly all the trees in the area were already infected. Fungicide injections may work, but this will be a tool used for high-value individual trees. In 2007, a Laurel Wilt Working Group was formed to strategize/prioritize next steps, to educate the public and land managers about the issue, and to maximize related work by coordinating efforts among interested agencies, organizations, and individuals.

20. You can help
Encourage others to collect red bay seeds. It is possible that some germplasm will be resistant to the disease. (note the forms included in the handouts)
Remind people not to transport mulch, firewood, etc.
Direct people to the Forest Health Protection site:
Images from

21. Contact information
Bud Mayfield, Forest Entomologist:
Florida Department of Agriculture and Consumer Services, Division of Forestry
PO Box Gainesville, FL
Randy C. Ploetz, Professor
IFAS, Tropical Research and Education Center, Plant Pathology Department, Homestead, Florida
Jason Smith, Assistant Professor
IFAS, Dept. of Forestry and Conservation
Gainesville, FL
Insert you regional/local diagnostic clinic information. You may also need to include your state Dept of Ag info.