Posts Tagged ‘laurel wilt’


In August and early September, the stars of Bee Heaven Farm are the shiny green Donnie avocados grown to almost football size. Stroll through the grove even this late in summer and you’ll see many, both on the branches and littering the ground below.

Summertime is a good time to visit fruit growers in Redland, because as you tour their groves, they’ll pick a fruit and let you taste it. So when the newest member of the Extension office, Tropical Fruit Agent Jeff Wasielewski, came to visit, that’s exactly what farmer Margie Pikarsky did. She took him for a walk around her farm, where they paused at different fruit trees, tasted a couple things along the way, and shared stories about the trees’ health and growth. “Visiting smart, forward-thinking growers like Margie is important for me as a learning tool and not just a social visit,” he said. (The UF/Miami-Dade County Extension office shares the latest agriculture information from University of Florida’s researchers with farmers and gardeners in the county. Some of the ways are through workshops, educational materials, field consulatations, and their web site.)

Tropical Fruit Agent Jeff Wasielewski and Margie Pikarsky open up an avocado.

Tropical Fruit Agent Jeff Wasielewski and Margie Pikarsky open up an avocado.

Margie’s pride and joy is the grove of over 90 avocado trees, which she herself planted back in 1996. She and Wasielewski stopped at one tree where she picked up a windfall avocado and handed it to him. It looked ready to eat, so he pulled pruning snips from a case on his belt, and cut open the fruit.

He’s a tall, easy going man with a ready smile and 18 years of tropical fruit experience, and 21 years of horticulture in South Florida. You might already know him from lectures, articles and videos he made for Fairchild Tropical Botanic Garden, where he was the Educational Outreach Specialist. He’s developed keen senses and loads of experience when it comes to tropical fruit and plants. All it took was one taste and he said the avocado was a day away from being perfectly ripe.

Further down the row of trees, he noticed a dead branch, which Margie snapped off. “Be careful,” he warned. “A dead branch like that can attract other beetles now suspected of carrying laurel wilt.” Margie explained that she removes dead branches from the trees as soon as she finds them, and trims the trees every year. So far her grove looks healthy, but laurel wilt disease remains a lurking concern.

Laurel wilt is a dangerous avocado disease that appeared in Miami-Dade County a few years ago. It is spread by the red bay ambrosia beetle, which is tinier than a grain of rice. Wasielewski  explained that the beetle burrows into healthy avocados and other trees in the laurel family. “It cultivates a fungus that eventually kills the tree branch by branch by disrupting its vascular system. Signs of the disease are quick branch dieback or tiny holes and sawdust towers where the beetles enter the tree. The tree will die very quickly if infected. Commercial growers are advised to quickly and completely remove the tree and its roots. The removed tree should be burned in place, out of fear of spreading infested wood to other groves and trees. Root removal is necessary because the disease may spread from tree to tree through root grafts,” he told me in an email.

So far there have been over 2000 trees removed due to laurel wilt in commercial groves in Redland, and  growers are worried, and anxious for a cure. When the first tree in a large commercial grove was suspected of having the disease, Extension held a standing room only meeting for growers, informing them of the threat. They continue to provide updated information on their website and with occasional meetings. (Yes, backyard trees in town are also at risk. Find info for homeowners at Save The Guac web site.)

Jeff and Margie

Jeff and Margie

As Tropical Fruit Agent, one of Wasielewski’s goals is to inform avocado growers of new research on combating laurel wilt. “It’s important that I am on the cutting edge of what is going on in the tropical fruit world,” he said. University of Florida has done tests, and complied a list of pesticides that will kill the ambrosia beetle. Unfortunately, none of them can be used in an organic grove. Local organic growers are pressuring the scientists to test substances approved for use in organic production.

Margie expressed her frustration to Wasielewski at the current lack of effective organic options. He said he would keep her informed as to new research into alternative treatments. “I want growers to have options as far as doing things in an environmentally friendly way. I let them know their options and the value of each option. Growers are then free to make a choice on how they want to proceed, but only if they are armed with new knowledge and multiple options,” he told me in an email.

For now, it’s wait and see how bad laurel wilt gets in Redland, and how quickly research can come up with solutions that all growers can use. Wasielewski is an important addition to the Extension office during a critical time for tropical fruit growers.

As for Bee Heaven Farm, over the years Margie has accumulated a wide variety of other tropical fruit trees, tucked away here and there among the vegetable beds. Sapodilla, carambola, longan, mango, and bananas are planted in various spots on her five acre farm. If her avocado trees have to go, she’ll plant different fruit trees and more vegetables, she once told me. But until then, she and other growers will put up a fight to save their groves.

Got a question about tropical fruit? Contact Jeff Wasielewski at 305-248-3311, ext. 227 or email at jwasielewski@ufl.edu .

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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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Did you go to the county commissioner budget meetings to state your case? No? You have several more chances. There are Budget Conference Committee (BCC) meetings on Aug 24, 25, 26 and 27 at commission chambers downtown.

The commission will hold final budget hearings on Thursday Sept 3rd at 5:01 pm and Thursday Sept. 17th at 5:01 pm . Currently the location of the hearings will be at the county commission chambers, but that might change as commissioners are expecting an overflow crowd. (The meeting location is not changing, but they are expecting a crowd. Marian, 8/21/09)

When you go, be sure to wear green. Green needs to be seen! And heard! Read and bring copies of these two documents Ivory Sheet and Green Sheet with you. They have facts and figures about the Extension program.

According to Cindy Dwyer, Master Gardener, “Remember that this is a game of numbers. If nobody shows up to protest, the result is a big zero. Organize a group of Master Gardeners and get your friends and neighbors who care about this issue to go to the meetings with you!”

If you can’t attend meetings, write letters to the commissioners. Find out how you can contact your commissioner here.

So why should CSA members and other locavores care? According to the Extension Ivory Sheet, “Miami-Dade County is considered as ground zero for new plant pests and diseases entering the United States. Many are first found in residential neighborhoods and quickly spread to agricultural areas. Cooperative Extension horticultural professionals are first responders for these invasive threats to agriculture, home horticulture, urban landscapes and the natural environment.”

Remember laurel wilt? It’s still here, and it’s not going away. Do you have an avocado tree in your yard? Cooperative Extension is the place to turn to if you want to learn how to keep your tree alive. If you’ve been enjoying Farmer Margie’s ginormous avocados this summer, and want to eat them again next summer, speak out in favor of Cooperative Extension at the commission meetings. Margie learned how to grow avocados and keep them healthy through training from Extension.

If the budget that Mayor Carlos Alvarez proposes is approved, the Extension office will close its doors forever on September 30. Everyone from the Master Gardener coordinator to the clerical staff will lose their jobs. Everyone from growers to locavores will feel the impact.

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