Insects v. orange juice lovers

 

In the battle of man (and his morning glass of Tropicana) versus a 3-millimeter long, mottled-brown insect, the insect has mostly been winning.

Asian citrus psyllid, and the disease it transmits, the uncurable-and-deadly huanglongbing, also known as citrus greening disease, has been cutting through citrus orchards in the major U.S. orange-producing states since 2005, when it was first discovered in Florida. Once huanglongbing, which is Chinese for yellow shoot disease, infects a tree, the fruit will sour, fall off, and eventually the tree will die.

Researchers have tried to halt the insect's spread in a variety of ways. They thought planting guava trees in between rows of citrus might stop it from crossing rows and transmitting huanglongbing.

Nope.

Growers also rip up sick trees and plant new, uninfected ones. But young trees are more susceptible to disease, and soon become infected again.

Officials have also tried imprisoning the insect. In 2005, the USDA implemented a quarantine on shipments of citrus plant material from states and territories known to have Asian citrus psyllid. But quarantine has expanded across multiple states and counties along with the bug, whose progress may be slowed, but not stopped, by such efforts.

And on March 31, officials with the California Department of Agriculture confirmed the first case of the disease in that state, the nation's second biggest citrus producer. This came on the heels of the first discovery of the disease in Texas, in January.

"This is the most significant plant disease invasion into California in modern history," Ted Batkin, president of the California Citrus Research board, told the Associated Press.

Asian citrus psyllid has devastated citrus producing economies worldwide. It first appeared in China, in the early 20th century, and has hopped country to country since. In Florida, the state with the largest citrus industry, huanglongbing has cost growers $1.36 billion in lost revenues, according to a recent report from the University of Florida.

California hopes to limit the spread of the disease northward, keeping it away from the productive San Joaquin Valley.

But the state's citrus growers might do better to pin their hopes on a newer line of research. This tactic, which uses genetic modification to introduce greening disease resistance in citrus trees (no naturally resistant trees have been found), is perhaps the most promising strategy yet in the ongoing war of farmers and OJ-lovers v. insect.

Just days before the late-March discovery of citrus greening in California, a researcher at Texas AgriLife, the extension branch of the land grant college Texas A&M, working at a USDA research and extension center in south Texas, announced a major success. Erik Mirkov had transferred huanglongbing-resistant genes from spinach into orange trees. Traditional opponents of genetic modification may find Mirkov's research more acceptable, because he has only been working with proteins that people already eat, like those in spinach.

Up at Cornell University, another land grant college, researchers are also transferring resistant genes into orange trees, but not from proteins we already eat. These researchers have introduced naturally-occuring insecticides originating in various bacteria, fungi, and plants into orange trees.They have also been successful in creating resistance.

Both types of trees are going to be planted in Florida groves this year to see how they fare, and if the fruit they produce fits growers' needs. Citrus producers say there isn't much time.
"Some of these growers in Florida, they say 'If you can't have something for us in five years, if you tell me it's going to take eight, we're dead,'" Mirkov told the Associated Press.

Ironically, the research center Mirkov works at is scheduled to close in June due to government budget cuts, which will shutter 259 Department of Agriculture facilities around the country as a means of saving $150 million. Mirkov's original research was funded by the agriculture department; it is now supported by a Florida citrus and juice producer.

Compared to the billions in potential losses to citrus growers in Florida, and California, Arizona, and Texas, the USDA savings are small potatoes.

But who wants to pay more taxes? Any of you orange juice drinkers want to step up?

Stephanie Paige Ogburn is the online editor at High Country News.

Image of Asian citrus psyllids courtesy USDA.

Image of spread of huanglongbing across Florida courtesy National Academies of Sciences.