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Citrus greening research in Florida yields new tool in battle against disease

By Paul Brinkmann
Victor Partel, a researcher at University of Florida, tests a new system to detect psyllid bugs that transmit disease to citrus trees. Photo courtesy of UF-IFAS.
1 of 2 | Victor Partel, a researcher at University of Florida, tests a new system to detect psyllid bugs that transmit disease to citrus trees. Photo courtesy of UF-IFAS.

ORLANDO, Fla., May 2 (UPI) -- A new machine being developed in Florida might provide another weapon against the spread of citrus greening disease, which has decimated crops worldwide.

The automated system would help detect and count the tiny pin-sized bugs that carry the disease, also called Huanglongbing or HLB. It would then give farmers a map of where the bugs have shown up in their fields, allowing for targeted precise insecticide spraying.

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The device, known as an Automated Psyllid Detection System, is under development at University of Florida's agricultural research station in Immokalee.

Orange grove owners like Francisco Pines are paying close attention to any new research or tools that could give them a leg up on the devastating blight. The disease entered Florida in 2005 and now is spreading in California. It is widespread in Brazil and China, among other locations.

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"It sounds viable. We have not used that, but I'm hopeful we could have something like that and I'm hopeful we will overcome this problem," said Pines, who is also a lawyer and commissioner with the state's Department of Citrus. His family operation in Highlands County has about 2,000 acres of citrus.

Citrus growers are looking for any advantage to control psyllids. The bugs, which originated in Asia, carry the HLB bacteria. According to the University of Florida, citrus production volume in the state declined by 71 percent from 2000 to 2017, primarily due to losses from greening.

Citrus greening affects all types of commercially grown citrus. In Florida, that is chiefly oranges and grapefruit.

But the disease has had a major impact. Florida's citrus harvest hit and all-time high in the 1997-98 season of 244 million boxes. By the 2015-16 season, that was down to 94.2 million boxes -- largely because of the greening disease.

A state study in 2016 said citrus greening had resulted in the loss of $4.64 billion over 10 seasons and eliminated more than 3,000 jobs. It also cost $1.76 billion in labor to fight the disease.

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"Monitoring the psyllid population is an essential component of citrus-greening management," said Yiannis Ampatzidis, assistant professor with the university's Institute of Food and Agricultural Sciences.

Until now, growers have used the so-called "tap sample method" to find and detect psyllids in their citrus trees. Using that technique, workers strike randomly selected branches and count psyllids that fall onto a sheet of paper. The system is reliable and efficient, but labor-intensive and time-consuming, he said.

The new system, currently towed by a tractor, has automated bars that tap branches, dropping bugs onto a platform below, where cameras detect the bugs. The bug locations are noted along with global-positioning satellite data, processed using artificial intelligence software developed by the university team.

The result is a detailed map showing farmers where the dangerous bugs may be entering a new field, for example.

"It's very important to know the number of psyllids. You can't just go and spray because you think it might be good," Ampatzidis said. "Chemicals are expensive and can harm the environment. Also the pests can develop resistance to certain chemicals."

The project is applying for a full patent and talking to companies about bringing the device to market. Ampatzidis said they researchers wanted to make their unit inexpensive, but he's not sure what the cost would be if it were mass produced.

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In Florida, some citrus growers have simply given up because the disease is so widespread, he said. He said the unit could be totally robotic if needed, eliminating labor costs. The same team of researchers is working on similar tools for weed detection and spraying.

"The big advantage here is to reduce use of chemicals," Ampatzidis said.

The machinery distinguishes between psyllids and other pests. According to the university, recent tests showed it detected psyllids with 90 percent accuracy. The test results and study was recently published in the journal Computers and Electronics in Agriculture.

Pines said he reads everything made available from IFAS and the state about greening research. "We rely upon research but we are spending a lot of money on the crop, and we're hopeful it will produce more," he said. "We are replanting as needed and are hopeful of expanding in the near future."

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