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.

“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
Vegetables
October 18, 2017
The 2018 State of the Vegetable Industry Survey Is Now Open!
How has this year performed for you? Share how things have gone this year – and your expectations for 2018 – in our shorter, more focused survey. Read More
Citrus
October 18, 2017
How to Keep Track of Climate Change
Use cool tools to find out how your production methods may change in the future, how much your area is at risk, and how to limit your own impact on the climate. Read More
Vegetables
October 18, 2017
Stop Viewing Fellow Growers as the Enemy [Opinion]
Instead, growers should focus on issues that benefit everyone, from gaining a stronger voice when negotiating with retailers, to finding a way to share ideas and costs on precision agriculture tools. Read More
Citrus
October 17, 2017
USDA Issues Disaster Declaration for Hurricane-Stricken Florida Farmers
Operators in designated counties eligible for emergency assistance. Read More
Fruits
October 17, 2017
Hirst Named American Society of Horticultural Science Fellow
Honor was presented during society’s annual meeting. Read More
Crop Protection
October 17, 2017
EPA Takes Steps to Reduce Risk of Drift-Related Herbicide Injury
With reports of dicamba injuries in tomatoes, peaches, grapes, and other crops, the agency works to reduce the impact of spray drift on vulnerable crops. Read More
Fruits
October 16, 2017
New Broad-Spectrum Herbicide Released by Nufarm
Grapple herbicide works on pre- and post-emergent weeds in orchards and vineyards. Read More
Flooded peach and grape groves from Irma at UF/IFAS HAEC
Citrus
October 16, 2017
Wrath of Hurricane Irma’s Rainfall Measured by the Trillions
Report says storm dropped enough gallons of water on Florida’s St. Johns River Water Management District to swamp 6.7 million football fields. Read More
Checking hop cones at UF/IFAS MREC
Fruits
October 14, 2017
USDA Seeks Applications for Next Round of Specialty Crop Research Grants
SCRI grants to total $48 million for 2018 fiscal year. Read More
Grapes
October 13, 2017
Fairgrounds Host California Fire Evacuees
Gallo will contribute $1 million to fire recovery effort and will match employee donations two-for-one. Read More
Fallen citrus fruit in wake of Irma
Citrus
October 12, 2017
Irma Rains Down on Florida Citrus Crop Estimate
Initial USDA forecast reflects the fruits of what was left behind by monster storm. Read More
Grapes
October 10, 2017
Wildfires Hit California Wine Country
California Gov. Jerry Brown declares state of emergency for northern counties impacted by flames. Read More
A water-logged citrus grove in Southwest Florida following Irma
Citrus
October 10, 2017
Impressions from Irma Indelible on the Florida Farmscape [Slideshow]
Striking images from the field reveal not only the storm’s destructive nature, but also paths to recovery and reconstruction. Read More
Crop Protection
October 9, 2017
Field Scouting Guide: Black Rot of Brassicas
Follow these tips for spotting and treating Xanthomonas campestris. Read More
Citrus
October 9, 2017
(We Won’t Back Down … ) Stand Your Ground for Agriculture
You don’t have to be a super hero, rock star, or award-winning scientist to aid farming. You can help by supporting professionalism in fields. Read More
The Latest
Vegetables
October 18, 2017
The 2018 State of the Vegetable Industry…
How has this year performed for you? Share how things have gone this year – and your expectations for 2018 – in our shorter, more focused survey. Read More
Citrus
October 18, 2017
How to Keep Track of Climate Change
Use cool tools to find out how your production methods may change in the future, how much your area is at risk, and how to limit your own impact on the climate. Read More
Vegetables
October 18, 2017
Stop Viewing Fellow Growers as the Enemy…
Instead, growers should focus on issues that benefit everyone, from gaining a stronger voice when negotiating with retailers, to finding a way to share ideas and costs on precision agriculture tools. Read More
Citrus
October 17, 2017
USDA Issues Disaster Declaration for Hur…
Operators in designated counties eligible for emergency assistance. Read More
Fruits
October 17, 2017
Hirst Named American Society of Horticul…
Honor was presented during society’s annual meeting. Read More
Crop Protection
October 17, 2017
EPA Takes Steps to Reduce Risk of Drift-…
With reports of dicamba injuries in tomatoes, peaches, grapes, and other crops, the agency works to reduce the impact of spray drift on vulnerable crops. Read More
Fruits
October 16, 2017
New Broad-Spectrum Herbicide Released by…
Grapple herbicide works on pre- and post-emergent weeds in orchards and vineyards. Read More
Citrus
October 16, 2017
Wrath of Hurricane Irma’s Rainfall…
Report says storm dropped enough gallons of water on Florida’s St. Johns River Water Management District to swamp 6.7 million football fields. Read More
Fruits
October 14, 2017
USDA Seeks Applications for Next Round o…
SCRI grants to total $48 million for 2018 fiscal year. Read More
Grapes
October 13, 2017
Fairgrounds Host California Fire Evacuee…
Gallo will contribute $1 million to fire recovery effort and will match employee donations two-for-one. Read More
Citrus
October 12, 2017
Irma Rains Down on Florida Citrus Crop E…
Initial USDA forecast reflects the fruits of what was left behind by monster storm. Read More
Grapes
October 10, 2017
Wildfires Hit California Wine Country
California Gov. Jerry Brown declares state of emergency for northern counties impacted by flames. Read More
Citrus
October 10, 2017
Impressions from Irma Indelible on the F…
Striking images from the field reveal not only the storm’s destructive nature, but also paths to recovery and reconstruction. Read More
Crop Protection
October 9, 2017
Field Scouting Guide: Black Rot of Brass…
Follow these tips for spotting and treating Xanthomonas campestris. Read More
Citrus
October 9, 2017
(We Won’t Back Down … ) Stan…
You don’t have to be a super hero, rock star, or award-winning scientist to aid farming. You can help by supporting professionalism in fields. Read More
Tomatoes
October 9, 2017
Heavy Spring Rain Causes Significant Dro…
The last time California -- which grows 95% of the all processing tomatoes in the U.S. -- came close to planting so few acres was in 1992. Read More
Apples & Pears
October 9, 2017
How to Transition to Multileader Product…
Use this guide to help you determine whether multileader production is a good fit for your farm. Read More
Grapes
October 7, 2017
Tips for Effective Vine Mealybug Managem…
Scouting, trapping, and mating disruption can help prevent populations of this pest increasing in your vineyard. Read More