Help On The Horizon

Help On The Horizon

Not one of Florida’s 600,000 acres of citrus is safe from the threat of greening. Some southern Florida groves have reached a 60% infection rate, and projections are for the disease to continue to spread. Removing infected trees and spraying for psyllids have not proven to be effective control measures.

But there is some good news to report. Researchers at the U.S. Horticultural Research Laboratory in Ft. Pierce are getting closer to finding new ways to slay the yellow dragon. Laboratory Director Calvin Arnold discusses some of the most promising research for short- and long-term greening remedies.

Investigating Guava

Several studies are underway to better understand how guava interplanted with citrus (a production practice used in Vietnam) suppresses psyllids. Lab tests have shown psyllids cannot live on guava. The next step, which is already in progress, is field testing. Plant pathologist Tim Gottwald and his team are cooperating with several Florida citrus growers to perform field trials in which guava trees are first planted, followed a year later by citrus trees.

“We know a volatile comes off leaves of guava to repel psyllids,” says Arnold. “This is our primary focus. But we also have preliminary data that the essence of the guava fruit also provides some repelling effect.”

The problem with using the guava fruit to repel psyllids, however, is that the Caribbean fruit fly is attracted to the fruit, creating a whole new pest problem. So that’s why USDA researchers are focusing on the leaves of the guava. By irradiating guava trees, the scientists can produce plants without seeds or fruit.

Intensifying Funding

Florida’s citrus industry saw $7.5 million in disease research funding for the 2007-2008 season. As part of its 2008-2009 Research Funding Strategic Plan, Florida Citrus Mutual (FCM) is seeking to secure more than $34.7 million to fund greening and canker research. This includes state and federal legislative appropriations as well as USDA monies.

The Florida Citrus Commission approved a preliminary budget that includes $20 million in grower box tax dollars for disease research, the full amount FCM recommended.

“We prefer growers do not have to plant guava (taking up valuable citrus acreage),” says Arnold. “The best option would be for a private company to develop a product to disperse the volatile in the grove. One possibility could be an atomizer attached to the trunks of trees at certain intervals that emits the volatile to move up the trees.” He thinks it would be easy to get EPA approval for this, since the volatile is a naturally occurring substance.

Bts Offer Possibilities

Another psyllid control method the lab is looking into is the use of Bacillus thuringiensis (Bt), a bacterium that acts as an insecticide. Bt has been proven to kill psyllids. The Bt research is the result of a group of citrus growers who visited Monsanto’s leadership in St. Louis to ask for help in the fight against greening.

“Monsanto has one of the best collections of Bt isolates in the U.S.,” says Arnold. “We stand a reasonable chance of economic control if we find the effective Bt.”

Trap-Crop Technique

Greening research also is being conducted on orange jasmine. Psyllids prefer orange jasmine over citrus. The idea is to use jasmine as a trap crop. Growers would plant rows of jasmine in the vicinity of their groves, then spray only the jasmine to kill the insects.

“These three techniques (guava volatiles, Bt, and orange jasmine trap crops) could be very immediate solutions,” says Arnold. “The answer to greening likely will not be a single method, but a combination of several new production techniques and methods.”

Enduring Remedy

“The long-term solution is to modify existing commercial varieties through genetic engineering so the trees are resistant to greening and canker,” says Arnold. His team is transferring anti-microbial peptides to give resistance, have already transformed Hamlin and Carrizo, and presently are evaluating these plants to determine if there is resistance to greening.

Arnold says growers may ask, “If we have the technology to engineer disease resistance in trees, why haven’t we done so already?” First, it takes time. It can take three to five years to grow the modified tree in the greenhouse and then the field. Second, there has been a fear of genetically modified organisms (GMOs) in the market, especially in Europe. In past discussions with growers, Arnold says they’ve told him GMOs would kill their export market. But now, the fear is gradually subsiding as growers become more desperate for greening solutions. Now they are saying, “Modify the trees, and we’ll deal with the market issues.”

According to Arnold, it’s important to understand that with genetic engineering, a Valencia would still be Valencia. It would look the same, taste the same, and grow the same. The only difference would be the disease resistance — and that could make all the difference in the world for the survival of Florida’s citrus industry.

Leave a Reply

Featured Stories
Protected AgricultureHow To Successfully Produce Vegetables In Controlled Environments
January 28, 2015
Greenhouse expert Merle Jensen offers pointers on growing systems, pest control, plant nutrition, harvesting, and more. Read More
IPMWhat You Need To Know To Maintain An Effective IPM Program In The Greenhouse
January 28, 2015
Greenhouse expert Karin Tifft discusses the importance of scouting, pest identification, control options, and the importance of sanitation. Read More
Apples & PearsPears Get A Hefty Shout-Out From Rapper
January 28, 2015
The pome fruit is on mainstream media's radar thanks to a rapper's quote and ensuing social media blitz. Read More
ProductionHighlights From The Mid-Atlantic Fruit And Vegetable Convention
January 28, 2015
Bio-control use, media literacy, and disease control were just a few of the topics discussed at the convention held in Hershey, PA. Read More
GrapesCalifornia Table Grape Growers Offer Agricultural Scholarships
January 28, 2015
The application deadline for the agricultural scholarships is 5 p.m., Feb. 13. Read More
GrapesNew Wine Hybrid Establishment Cost Resource Available
January 28, 2015
Research from Cornell University breaks down the cost of producing hybrid winegrapes. Read More
FertilizerEasy Access To Fertilization Guidelines
January 28, 2015
New, easy-to-follow brochures take the guesswork out of almond and walnut fertilization. Read More
BerriesDormant Pruning Tips For Your Berries
January 28, 2015
Proper dormant pruning increases berry size and improves overall health of blackberry and raspberry plants. Read More
NutsHow Freezing Temperature Affect Bearing and New Trees
January 28, 2015
Key points before and after the critical bloom period make exposure to freezing temperatures relevant. Read More
CitrusFlorida Citrus Is Still A Big Deal [Opinion]
January 28, 2015
Even while in the grips of greening, citrus continues to be a big contributor to the Sunshine State's economy. Read More
The Latest
Protected AgricultureHow To Successfully Produce Vegetables In Controlled En…
January 28, 2015
Greenhouse expert Merle Jensen offers pointers on growing systems, pest control, plant nutrition, harvesting, and more. Read More
IPMWhat You Need To Know To Maintain An Effective IPM Prog…
January 28, 2015
Greenhouse expert Karin Tifft discusses the importance of scouting, pest identification, control options, and the importance of sanitation. Read More
Apples & PearsPears Get A Hefty Shout-Out From Rapper
January 28, 2015
The pome fruit is on mainstream media's radar thanks to a rapper's quote and ensuing social media blitz. Read More
ProductionHighlights From The Mid-Atlantic Fruit And Vegetable Co…
January 28, 2015
Bio-control use, media literacy, and disease control were just a few of the topics discussed at the convention held in Hershey, PA. Read More
GrapesCalifornia Table Grape Growers Offer Agricultural Schol…
January 28, 2015
The application deadline for the agricultural scholarships is 5 p.m., Feb. 13. Read More
GrapesNew Wine Hybrid Establishment Cost Resource Available
January 28, 2015
Research from Cornell University breaks down the cost of producing hybrid winegrapes. Read More
FertilizerEasy Access To Fertilization Guidelines
January 28, 2015
New, easy-to-follow brochures take the guesswork out of almond and walnut fertilization. Read More
BerriesDormant Pruning Tips For Your Berries
January 28, 2015
Proper dormant pruning increases berry size and improves overall health of blackberry and raspberry plants. Read More
NutsHow Freezing Temperature Affect Bearing and New Trees
January 28, 2015
Key points before and after the critical bloom period make exposure to freezing temperatures relevant. Read More
CitrusFlorida Citrus Is Still A Big Deal [Opinion]
January 28, 2015
Even while in the grips of greening, citrus continues to be a big contributor to the Sunshine State's economy. Read More
FruitsUSDA Forecast Predicts Normal Water Supply For Parts Of…
January 27, 2015
The Southwest, Sierra Nevada region, and Pacific Northwest are starting the year drier than normal. Read More
Apples & PearsThe Story Of Honeycrisp Is One Of Challenges And Succes…
January 27, 2015
‘Everything’s different’ in this world of 150 million 40-pound box world of apple growing. Read More
BerriesWhy You Should Be Growing Black Raspberries
January 27, 2015
Amazing health benefits for consumers and production and marketing benefits for the grower make this berry a must-consider option for your operation. Read More
Apples & PearsThe Dark side Of Honeycrisp
January 27, 2015
Growers say there’s a love-hate relationship with America’s darling apple. Read More
Apples & PearsExpanded Market Access For U.S. Grown Apples To China
January 26, 2015
Agreement expected to boost apple exports by $100 million per year. Read More
CitrusNominees Sought For Florida Agricultural Environmental …
January 26, 2015
Honor recognizes those developing and adopting environmentally innovative farming practices. Read More
CitrusIncreased Global Trade Opportunity Equals New Threats F…
January 26, 2015
Despite expanding business abroad, Florida Agriculture Commissioner Adam Putnam says he's confident in the protocols in place to prevent entry of invasive pests and disease. Read More
GrapesEstimates Vs. Actual: The Cost Of Installing A Vineyard
January 26, 2015
The true costs of developing a vineyard depend on variables such as vine selection, trellising, and labor. Read More