UF/IFAS researchers are working on a decision-support app to help policy makers and growers decide the best regional treatment options for laurel wilt disease, which is challenging Florida's $35 million-a-year avocado crop.
Laurel wilt disease is spread by several ambrosia beetle vectors. People, whether they grow avocados or not, can spread the beetles when they move infested wood products – for example, firewood and wood-turner wood -- UF/IFAS researchers say. UF/IFAS researchers are trying to get all this spreading under control.
To help develop the app, scientists are using the HiPerGator, a supercomputer on the main University of Florida campus in Gainesville, to analyze massive amounts of data.
“This network analysis app will aid policy makers by providing input about how such things as subsidies or penalties for disease management are likely to affect growers' management decisions and resulting disease spread,” said Berea Etherton, a doctoral student in plant pathology in the UF/IFAS College of Agricultural and Life Sciences. “Better regional management as a whole benefits individual growers.”
Scientists hope to gain better regional control of laurel wilt through machine learning for analysis of satellite-images. Those analyses train an artificial intelligence system to recognize patterns from remotely sensed images, said Etherton, who's conducting the research under the supervision of her advisor, UF/IFAS Professor Karen Garrett.
“In the next steps for the project, we plan to integrate satellite image analysis and disease recognition to support decision makers considering the best management strategies,” Garrett said. “The computational demands of the machine-learning tools in this project will benefit from the new HiPerGator resources.”
The UF supercomputer will allow for rapid analysis of large data sets, Etherton said. This project is designed to pass the benefits of the HiPerGator on to the growers, as decision support will include input from satellite images and high-speed processing.
Florida avocados are grown almost entirely in Miami-Dade County. Many consumers love to eat them in a variety of ways, including in guacamole dip. But even as laurel wilt disease damages avocado trees, demand for the fruit continues to rise in global markets. According to UF/IFAS economists, about 80% of Florida's avocados are sold outside Florida and the industry has an economic impact of about $100 million to the state's economy.
Garrett and Etherton are working with researchers at the UF/IFAS Tropical Research and Education Center and the U.S. Department of Agriculture. They all hope the app will help control laurel wilt on a regional basis.
“Any technology that is accessible, efficacious and economical and helps producers combat laurel wilt is welcome,” said Jonathan Crane, UF/IFAS professor of horticulture and a tropical fruit Extension specialist at TREC.
“Managing crop diseases is challenging, because the success of one grower's management strategies often depends on how well other growers are managing the disease. We are working to contribute to regional management strategies,” Garrett said.
laurel wilt trees
Posted on
Wednesday, November 25, 2020 at
11:08 AM
- Author:
Brad Buck, U of F
Focus Area Tags: Agriculture
Laurel Wilt-Ambrosia Beetle Grower's and Advisory Panel meeting to update and discuss research and extension programs supported by the USDA research grant.
Purpose: The Univ. of Florida/IFAS created a panel consisting of local commercial avocado growers and handlers and scientists for the USDA grant on laurel wilt and ambrosia beetles. The purpose of the meeting is for researchers to update avocado growers and the advisory panel on the progress of research on this grant and to discuss future research and extension plans. This meeting is open to anyone to attend.
Date: July 23, 2020
Time: 10AM-12PM
Location: ZOOM, recording available HERE
AGENDA
Dr. Crane, welcome and introduction
Brief updates, plans and discussion:
1. Dr. Schaffer, Environmental Plant Physiology – Laurel wilt susceptibility of avocado scions and rootstocks in relation to physiology and stem anatomy
2. Dr. Gazis, Plant Pathology – Laurel Wilt - Plant Pathology: Research Accomplishments, Current Work, and Future Direction
3. Dr. Carrillo, Entomology – Update laurel wilt ambrosia beetle research
4. Dr. Evans and Mr. Ballen, Ag Economics - current work and work in progress and plans
5. Dr. Crane and Mr. Wasielewski – Current extension program and plans
laurel-wilt-and-avocado-trees
Posted on
Monday, July 27, 2020 at
7:17 AM
Focus Area Tags: Agriculture
The Mediterranean Oak Borer (Xyleborus monographus) is an ambrosia beetle that was found infesting several valley oak trees in Calistoga, (Napa County) California in 2019.
The extent of its distribution within Napa County and neighboring Sonoma and Lake Counties is currently undetermined. It is not believed to have spread to other parts of the state. However, there is considerable potential for the beetle's range to expand as they can be moved in infested wood and the females can fly. Native to Europe, the pest is found in a variety of climates, including Mediterranean, and it is likely capable of establishing over much of California.
In Europe, the beetles are known to attack a moderate range of trees in the oak and beech family, but that range could be much narrower or broader in California. They appear to prefer to infest trees that are already suffering from drought or other pests or diseases. California forests are periodically under stress from drought, fire, and disease, so they may be especially vulnerable to this beetle.
Adult females tunnel into trees, usually at points where the bark is thin or cracked, leaving entry holes measuring around 1/16th of an inch. Inside their branching tunnels (referred to as "galleries"), they introduce fungal spores that grow in fungal "gardens." Besides being the primary food of the beetle larvae and adults, the fungi may damage or kill the tree over time. The trees associated with the 2019 finds of infestation in Calistoga showed symptoms including wilting, defoliation, and broken branches, and the infested wood was discolored, presumably by the fungus. In addition to injuring or killing living trees, the beetles are reported to damage cut oak wood.
In Napa County, the beetle has been observed to colonize trees from the top, sometimes starting from branches high in the canopy, and then as the population slowly expands, reaching massive densities in the lower trunk. This is a behavior known for the invasive shot hole borer that is currently threatening a wide variety of trees in Southern California, but not for the Mediterranean oak borer in its native Europe.
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Posted on
Monday, July 20, 2020 at
5:15 PM
Focus Area Tags: Environment
Reposted from the UCANR News
California oak woodlands are highly prized ecoregions where stately trees, many of them hundreds of years old, are cornerstones of a habitat for wildlife and native plants. Sadly, some of these ecosystems are seriously threatened by exotic pests and diseases, encroachment by less desirable vegetation, and wildfire.
Each year, UC Cooperative Extension hosts workshops to share scientific developments aimed at conserving these important habitats – and the economic value of ranching – on oak woodlands, which are found on the lower elevation slopes of the Sierra Nevada, the Coast Range and other foothill areas of California.
Typically, the workshops are held in person and draw moderate-sized audiences for presentations, questions and answers, and field trips. Because of the COVID-19 pandemic, this year's workshop was offered online in April with pre-recorded presentations available for viewing at the participants' convenience and a live question-and-answer session on Zoom.
The retooled event garnered 500 registrants, over 300 views of the YouTube videos and 140 participants in the live Q&A session. The presentations and Q&A session are still available online for future viewing as well at http://cemendocino.ucanr.edu/Forestry/Workshops/California_Oak_Health.
“People from all walks of life participated, including those with professional and personal interest in oak woodlands,” said Yana Valachovic, UCCE forest advisor in Humboldt and Del Norte counties and a conference organizer.
Presentations at the 2020 conference included the following topics:
Encroachment by Douglas-fir
In Northern California, the biodiversity of oak woodlands is being threatened by Douglas-fir encroachment. The oaks' shade helps the young conifers get established with protection from harsh sun. In time, the fast-growing Douglas-fir trees pierce the oak canopies and begin to crowd out the areas' native understories, which are important for the diversity of birds, mammals and reptiles attracted to oaks.
As the Douglas-fir continue to grow and multiply, they threaten the very lives of the oak trees and the unique ecosystem they dominate.
To better understand the Douglas-fir encroachment, Valachovic established 10 research sites in Humboldt and Mendocino counties to gather information about the fate and the age of oaks. She and her research partners determined the ages of the oaks and firs, and counted the seedlings, saplings, snags and understory vegetation.
“With this research, we were able to demonstrate that even though the oak trees can be smaller in diameter, they are much older than the Douglas-fir trees,” Valachovic said. “The encroachment process is happening quickly, and the oaks are falling out of the system.”
The shift appears to have been initiated in the mid-19th and early-20th centuries, coinciding with the Gold Rush and wildfire suppression.
With the data confirming Douglas-fir encroachment, Valachovic turned her attention to oak woodland restoration. At 14 sites in Humboldt and Trinity counties, her team studied the effects of Douglas-fir removal.
“Grasses and forbs under the oaks reestablished. Diameter growth on the oaks increased,” she said.
These research findings contributed directly to changes in policy that had previously limited landowners' ability to remove and sell conifers encroaching on oak woodland. The research also helped create new funding opportunities to support oak woodland restoration and conservation in Northern California.
Case study of oak woodland wildfire recovery
In July 2018, about two-thirds of the 5,289-acre UC Hopland Research and Extension Center was burned by the River Fire.
The transformation of the land, which had likely been without a large wildland fire for at least 100 years, was intense and stressful, said UC Cooperative Extension forest advisor Michael Jones. However, it also provided a unique opportunity for researchers to compare the impact of wildfire on the resiliency of vegetation on grazed and ungrazed oak woodland.
Jones established 35 one-fifth acre research plots at the research center and collected data two months following the fire and one year later. The research will continue in the future to better understand long-term impacts, but Jones was able to share revealing early results at the workshop.
Right after the fire, in severely burned areas areas, the future of the oaks looked ominous. Jones predicted 40% tree mortality.
“The oaks were exposed to persistent, intense heat. They were cooked,” he said. “But two months after the fire, we were already seeing basal sprouts. This was an amazing response by the trees. Oaks are pretty damn tough.”
A year after the fire, surveys showed that tree mortality in the burned areas was 25%, much less than Jones' early predictions. While some management for specific situations in severely burned areas may be necessary – such as removal of hazard trees, reducing fuels in defensible spaces or removal to control invasive species – the results of this work show the trees recover naturally.
“Esthetically, I know these systems aren't as pleasing as they were before, but ecologically, they are healthy and recovering,” he said. “In 100 years, it will look just as good as before the fire.”
Fire impacts in woodland areas previously grazed and not grazed
The fire on the research station also permitted Jones to compare the fire's differing impact on non-grazed and grazed oak woodland. At first, the grazed areas looked almost unscathed with minimal flame scorching on the bark, while an area where the pasture hadn't been grazed for 25 years had evidence of much higher severity fire.
“Grazing is a phenomenal way to help manage fuels,” Jones said. However, the grazed areas displayed ecological shortcomings a year later.
“In grazed pastures, the large mature trees were still alive, but there was no oak regeneration (basal sprouting or seedlings),” Jones said. “In the ungrazed area, a lot of biomass had been killed, but there's nearly 100% resprout of oak trees and we have an impressive amount of oak seedling recruitment.”
Jones said he isn't discouraging grazing.
“But it is important to protect sites from grazing, and especially wildlife browse, when a landowner or land managers' objectives are to regenerate or conserve oak woodlands,” Jones said.
New ambrosia beetle another threat to California oaks
Akif Eskalen, UC Cooperative Extension specialist in the Department of Plant Pathology at UC Davis, has identified a new insect-fungus team that causes oak borer wilt in Northern California Valley and Blue Oaks. It is an ambrosia beetle, commonly known as Mediterranean Oak Borer, which carries several fungi in its mouth. The beetle bores into the tree and introduces fungi to grow for food. The fungi spreads and disturbs the transportation of water and nutrients, causing wilt in the tree.
The oozing and staining lesions on the bark are similar to other oak fungal diseases, such as sudden oak death. The beetle – native of Mediterranean basin countries in Africa, Asia and Europe – cannot fly far, so most likely is transported for long distances on infested firewood.
During the workshop, Eskalen suggested not moving firewood, removing heavily infested trees and chipping infested wood into 1-inch particles to reduce the spread of the ambrosia beetle and its fungal partner. He asked viewers to report any suspected oak tree infestations to the local agricultural commissioner, CDFA Diagnostic Laboratories, UC Cooperative Extension advisors or CALFIRE. Chemical options for sparing oaks from the ambrosia beetles' devastation are under investigation.
Threats to oaks and other native plants from root rotting Phytophthora
Restoration plantings have inadvertently introduced plant pathogens to native oak woodland ecosystems in California, said Ted Swiecki of Phytosphere Research, an organization that provides consulting services related to natural resource management, horticulture, urban forestry and agriculture. The group of pathogens causing the damage are largely from the Phytophthora genus, first described in the 1860s. The name translates from Greek to “plant destroyer.”
Swiecki has observed when Phytophthora infested plants and soils are introduced to native habitats, the pathogens can attack various native plants, including toyon, madrone, manzanita and full-grown oaks. Once established, the pathogen can spread along drainages, by moving soil from one area to another and by hitchhiking on equipment, tires and hiking boots.
The pathogen can easily be overlooked at nurseries, which, by their nature, have conditions that favor Phytophthora development. Plants at nurseries are well watered, have high root density and are often placed on the ground where they can pick up pathogens.
He said the best approach to tackling Phytophthora is not using nursery stock for restoration or beautification of natural oak woodland. Direct seeding, using natural regeneration, or onsite propagation are safer ways to enhance vegetation in oak woodland.
“It's easier to prevent Phytophthora from being introduced in the first place and much cheaper and more effective than trying to eradicate it later,” Siewcki said.
Posted on
Wednesday, April 29, 2020 at
3:48 PM
- Author:
Jeannette Warnert
Tags:
Akif Eskalen (8),
ambrosia beetle (19),
blue oak (9),
firewood (23),
grazing (55),
insects (170),
John Bailey (5),
Michael Jones (6),
oak woodland (13),
wildfire (358),
Yana Valachovic (43)
Laurel Wilt Disease of Avocado and the relatives of avocado in the Laurel Family has devastated the the forests along the east coast from North Carolina down to Florida and along the Caribbean into Texas. It has caused significant losses to wildlands and to the Florida avocado industry.
The extent of the native tree loss is shocking and there is very little that can be done to correct the problem, other than to curb the spread of contaminated wood that is spread by humans, There has been some success in the avocado orchards. While there is no "silver bullet", there is some progress, e.g. pruning to increase light levels to suppress Ambrosia Beetle activity. In addition, research has continued for:
- Vaccinations to protect avocado trees from the LW pathogen
- Developing a faster LW diagnostic tool
- Screening scions and rootstocks for tolerance/resistance
- AB control tactics and suppression
- Molecular understanding of the pathogen
- Economics and the LW epidemic
Read the latest results in these two recent publications:
Recommendations for the Detection and Mitigation of Laurel Wilt Disease in Avocado and Related Tree Species in the Home Landscape
Recommendations for Control and Mitigation of Laurel Wilt and Ambrosia Beetle Vectors in Commercial Avocado Groves in Florida1
Photo: Dead avocado trees from Laurel Wilt in Florida
laurel wilt trees
Posted on
Wednesday, April 22, 2020 at
7:19 AM
Focus Area Tags: Agriculture