Posts Tagged ‘redbay ambrosia beetle’

Avocado tree infected with laurel wilt. The fungus carried by the beetle causes entire branches to turn brown and die. Photo courtesy UF/IFAS.

If you have avocado trees growing in your yard, heads up! The feared redbay ambrosia beetle has surfaced in west Miami-Dade County, in Emerald Lakes. One beetle was caught in a trap on March 2. Scientists are testing the captured bug to see if it carries a fungus that kills avocado trees (and others in the bay family) by causing a fatal wilt. There was a scare last summer, but that proved to be a false alarm. This time it looks like the real threat has arrived.

Florida Dept. of Agriculture recommendations for homeowners:

The public can help prevent the spread of the redbay ambrosia beetle and laurel wilt disease by following these simple suggestions:

— Become familiar with the signs of laurel wilt disease and redbay ambrosia beetle and be on the lookout for evidence of the pest/disease on your trees. http://www.doacs.state.fl.us/pi/enpp/pathology/laurel_wilt_disease.html

— Use local firewood only. Do not transport firewood from other states because destructive pests and diseases, such as redbay ambrosia beetle and laurel wilt, can hitchhike into Florida on infested firewood. http://www.doacs.state.fl.us/pi/videos.html

— Do not transport host trees (redbay, swamp bay, avocado, sassafras, pondspice, pondberry and others in the Lauraceae family) unless purchased from a registered nursery.

— If your Lauraceae-family tree dies, use one of UF/IFAS’s recommended methods of disposal.

People who suspect their trees might be infected with laurel wilt or think they have found a redbay ambrosia beetle are urged to contact the DPI helpline at 1-888-397-1517.

People who would like to submit a plant or insect sample, visit this web site for sample submission instructions http://www.doacs.state.fl.us/pi/enpp/pathology/laurel_wilt_disease.html

Know your foe: redbay ambrosia beetle. Actual size is about half a grain of rice. Courtesy UF/IFAS.

Discovery of ambrosia beetle in Miami-Dade no cause for panic, scientists say

Last summer, there was a premature announcement of the presence of a tiny beetle that has the power to spread fungus that can severely damage avocado trees. That turned out to be an unfortunate mistake, triggering some growers to cut down and burn trees and apply pesticide.

This month, there’s no mistaking it: One redbay ambrosia beetle was found in a trap in west-central Miami-Dade County on March 2.

But scientists say a single beetle shouldn’t scare Miami-Dade growers — whose trees cover nearly 7,000 acres of South Florida — just yet.

“It’s not cause for panic, thank God,” said Jonathan Crane, a tropical-fruit plant specialist with the University of Florida’s Institute of Food and Agriculture Sciences in Homestead.

Read the rest of the article here.

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This summer, there was great concern among commercial avocado growers in Redland (including Bee Heaven Farm) about the apparent discovery of the redbay ambrosia beetle, which rapidly kills avocado trees, and has been located in North and Central Florida. At least one tree in Redland was suspected of infestation and was burned. UF/IFAS held a workshop (which was blogged) giving information about the beetle and laurel wilt, the lethal fungal infection that it causes.

If you have avocado trees on your property in town, don’t think you’re immune. Learn what the signs are and watch your trees carefully. There’s good information at Save The Guac and the UF/IFAS sites.

Farmer Margie told me in summer that she will take a wait and see attitiude with her grove. Both she and Gabriele Marewski of Paradise Farms (who also raises avocados) are cautiously optimistic that a healthy, unstressed tree may not get infested and die. So far so good, fingers crossed.

Here’s a good follow-up article about the situation, published in the Miami Herald on Dec 26th.

Avocado growers fear spread of Asian redbay ambrosia beetle

After enjoying a season of near record-high avocado prices, farmers of Florida’s second-largest tropical fruit crop are now worried about a potentially deadly invasive pest.



This year’s avocado season is making farmers happy: The 920,000-bushel crop, grown mostly in southern Miami-Dade County, is fetching prices that are almost 50 percent better than a few years ago. But as the season comes to a close, those in the Florida avocado industry are casting a wary eye to Martin County, where the redbay ambrosia beetle continues its march southward.

Growers, scientists, and the local, state and federal governments are in a race against the beetle as it makes its way south to the $30 million avocado industry.

The beetle, believed to be a native of Asia, is described by scientists as smaller than Lincoln’s nose on the penny. But it carries a fungus that has proved lethal to many trees in the laurel family, including redbays and avocados, from the Carolinas through Georgia, and now Florida. There is no method to cure the disease.

After citrus, avocados are Florida’s largest tropical-fruit industry. This year’s crop was more than 50 million pounds, virtually all of that grown on 7,500 acres in Miami-Dade.

“The avocado industry is very concentrated in one area,” said Craig Wheeling, president of Brooks Tropical in Homestead, one of the largest growers, packers and shippers of Florida avocados. “It’s kind of an all-or-nothing fight down here.”

Wheeling said his best avocados were getting about $16 a bushel — 45 percent better than the $11-a-bushel prices three years ago. He attributed the higher prices to not just a smaller crop, but to growing demand for Florida avocados. And he said that’s what makes it even more crucial that scientists find a way to combat the beetle and the fungus-causing disease it carries.

Females carry the fungus spores in a special pouch within their mouths. When the insects bore into a healthy tree to check if it would be suitable for nesting, the tree is inoculated with fungi that cause a disease called laurel wilt. As it spreads, the tree’s water system is disrupted, causing the leaves to wilt so quickly they don’t even fall off.

The larvae and adult females feed off the fungus — essentially, the beetle carries its farming system with it, said Jonathan Crane, a tropical-fruit plant specialist with the University of Florida’s Institute of Food and Agriculture Sciences in Homestead.

There are dozens of varieties of beetles that have a symbiotic relationship with a fungus it carries. The one beetle/fungus combination that has proved deadly to the redbay and Florida avocado tree is a specific variety with the scientific name raffaelea lauricola. It was first detected in Georgia in 2002.

It took a few years to spread through Georgia and was first found in Florida’s northern counties in 2005. On its own, the beetle can fly about 20 miles.

It has spread exponentially quicker the past two years to Central Florida, experts believe, because diseased trees have been cut down for firewood and brought south.

In late July, the local industry panicked after the state issued a press release saying a confirmed case of the beetle had been found in a Homestead grove.

Growers, including Brooks, spent hundreds of thousands of dollars to cut down and burn trees that looked weak or infected, and to spray groves with extra pesticides.

That initial test proved to be a false positive because the science behind tracking and typing the fungus is just developing, said University of Florida forest pathologist Jason Smith. The beetle and fungus have never been studied in Asia, where it is believed to come from, because trees there haven’t died.

“Nobody had ever looked at this,” Smith said.

It took weeks to confirm that the disease hadn’t reached Miami-Dade. Even so, the industry remains on guard.

“It’s still a threat,” said Miami-Dade County’s agricultural manager Charles LaPradd. “What I would love to say is that it will never get down here, but that’s fantasyland.”

Local growers say what happened this summer was a test.

The summer scare caused growers to start regular meetings with local, state and federal agriculture officials and scientists, who said they are close to a method that would confirm the disease in a day or so.

Most of the research is being spearheaded by the University of Florida, which received a $1.2 million USDA grant to find a way to beat the beetle.

One possible method might involve sterilizing the large equipment that is used within groves to prune trees, Smith said. Others are looking at the natural resistance that has been found in Asia and among some local varieties of trees. Additional research is going into fungicides that need to receive federal approval before being used.

In the meantime, the state agriculture department has also started a marketing campaign based on one of the fruit’s most popular uses, guacamole, at www.savetheguac.com. It’s designed to help educate the public about moving firewood and how to spot diseased trees.

“There are tens of thousands of backyard avocado trees in South Florida,” said state agriculture spokesman Mark Fagan.

“We can’t go into every backyard and inspect every avocado tree — we need the public’s help.”

© 2009 Miami Herald Media Company. All Rights Reserved. http://www.miamiherald.com

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If you have only one avocado tree in your yard, or a grove full, come get the latest information on the laurel wilt disease. It was spotted in Northern Florida earlier this year, and this summer in a grove in Redland. If the disease spreads, it could wipe out not only commercial groves but also backyard trees. I’ve blogged earlier about this in more detail the post titled Avocados are threatened.

Dr. Jonathan Crane of UF IFAS/TREC will lead the Laurel Wilt Disease and Redbay Ambrosia Beetle Research Symposium on Tuesday, November 3, 2009 from 8:30 AM to 3:00 PM. Download the agenda here (PDF 60 KB).

Miami-Dade County Cooperative Extension Service Auditorium
18710 SW 288th Street, Homestead, FL 33030-2309.

Driving Directions:
Traveling south on the Florida Turnpike (Homestead Extenstion), take Exit #5 (Biscayne Drive / SW 288th Street), and go west for about 5 miles. The Extension Office is at the corner of SW 288th Street and SW 187th Avenue (Redland Road), on the left. It is a one-story, beige, block building.

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Florida avocados

Florida avocados

Take a good look at this season’s avocados, and savor the flavor. This season might be the last time you’ll see and taste Florida avocados, if the laurel wilt disease gets out of control in Miami-Dade County. It’s caused by the tiny redbay ambrosia beetle that carries a fungus which kills avocado trees fairly quickly. In Brevard County, where there are mostly neighborhood avocado trees, UF/IFAS researchers spotted the disease in October 2008, and by May 2009 the same trees were dead.

Last week the rumors were flying among growers that laurel wilt was spotted in a Miami-Dade grove. This Wednesday night it was confirmed by UF/IFAS scientists at an emergency meeting held at the Miami-Dade County Extension Service office. Over 120 concerned avocado growers packed into the meeting room to hear the grim news. This tiny beetle presents an enormous threat to their livelihood.

One tree suspected of laurel wilt came back positive for the disease using DNA testing, and four additional samples had been taken from three other groves for testing. This is the first time the fungus has been spotted in a commercial grove in Miami-Dade County, and it could severely harm a $12.7 million industry.

There are 892 growers and 6773 acres of avocado groves in the county, according to the USDA’s 2007 survey. If the disease cuts Florida’s commercial avocado crop in half, which could happen, it could cost the state $27 million in total economic impact and enough lost worker hours to equal 275 full-time jobs, according to UF/IFAS.

Plant inspectors and insect trappers from the Florida Dept. of Agriculture are surveying the ag production area from Goulds south — 140 commercial groves numbering 7000 acres, according to their calculations. They’re also setting sentinel traps to track the beetle, similar to what’s being done with fruit flies. Their survey should be 70-80 percent complete by this Friday Aug. 7. At the time of the meeting, they have not yet found signs of the beetle or laurel wilt.

If you’re a homeowner and you have an avocado tree in your yard, check it often for signs of beetle infestation or laurel wilt. If you see anything suspicious, call the Division of Plant Industry at 305-252-4360 or 888-397-1517 and an inspector will come take a sample for DNA testing. If the sample comes back positive, you’ll be instructed on how to treat or properly dispose of your tree. Do NOT cut it down and throw it on the street for pickup, because that could help spread the beetle and its fungal infection to other trees in the neighborhood.

State representatives Ileana Ros-Lehtinen and Mario Diaz-Balart were instrumental in pushing the USDA to give UF a $1.9 million grant to find a way to mitigate and manage laurel wilt. Other local politicians who are actively involved are County Mayor Carlos Alvarez and County Commissioner Katy Sorensen.

On the other hand, Mayor Carlos Alvarez recently drafted a new county budget that slashed Extension office funding to almost zero. The office also relies on matching funds from UF/IFAS to educate and support growers and homeowners about plant diseases and various agricultural issues. This drastic cut couldn’t come at a worse time. County commissioners are meeting on Sept. 3 and 17 (after their August vacation) to vote on the new budget. Please take the time to call or email your county commissioner and tell them not to cut funds for Extension and local growers! For locavores, doing that’s a no-brainer, right??

Miami-Dade County Mayor Carlos Alvarez http://www.miamidade.gov/mayor/
Miami-Dade County Commissioners http://www.miamidade.gov/commiss/
Representative Ileana Ros-Lehtinen http://ros-lehtinen.house.gov/
Representative Mario Diaz-Balart http://mariodiazbalart.house.gov/index.html

More info on redbay ambrosia beetle

More info on laurel wilt

Miami-Dade County Extension Service http://miami-dade.ifas.ufl.edu
Miami-Dade DERM http://www.miamidade.gov/derm/
UF/IFAS Tropical Research & Education Center http://trec.ifas.ufl.edu/
Fla. Dept. of Agriculture and Consumer Services http://www.doacs.state.fl.us

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