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Some Citrus Fruits Are In Danger. Here's How Scientists Are Working To Save Them

A greening disease is threatening citrus trees from Florida to California but scientists might have a solution.
A greening disease is threatening citrus trees from Florida to California but scientists might have a solution.

Oranges and grapefruit are under siege in California. Growers are under pressure to protect all citrus varieties from an increasing threat that's already hit Florida.

Citrus Greening Disease, or HLB, was detected in Florida more than 10 years ago. Researchers are still trying to figure out how to protect the fruit from a disease with no effective commercial treatment.

Now HLB is in California. It has been detected in 2,000 trees but not yet in commercial orchards.


But there is hope on the horizon. University of California Riverside (UCR) researchers and their partners are perfecting a fruit that may be resistant to the greening disease.

Through genetic engineering, UCR scientists like Mikeal Roose is crossing U.S. varieties with Australian ones. A fruit down under similar to a lemon or lime, seems to have some resistance. Roose is crossing the U.S. variety with an Australian one and then again with an American citrus fruit.

"It's still a little bit difficult but it's doable," he says.

UCR has a $4.67 million grant from the National Institute of Food and Agriculture and is partnering with Texas A&M, the University of Florida, Washington State University and the U.S. Department of Agriculture.

UCR's Chandrka Ramadugu is leading the project. Eight years ago she was in Florida testing microcitrus varieties that had some natural resistance. "The goal is to have plants that have proven to be similar to citrus, that's acceptable by the public, but also to have part of the Australian citrus genome so it will be resistant to the disease," she says.

The challenge is to get the fruit to also taste good. This all takes time, maybe four to five years as all the crossbreeding takes place and is grown in different places and environments.

Scientists are also altering the soil to see if that could provide some immunity.

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With more than 30 years of journalism experience in the Greater Cincinnati market, Ann Thompson brings a wealth of knowledge and expertise to her reporting. She has reported for WKRC, WCKY, WHIO-TV, Metro Networks and CBS/ABC Radio. Her work has been recognized by the Associated Press and the Society of Professional Journalists. In 2019 and 2011 A-P named her “Best Reporter” for large market radio in Ohio. She has won awards from the Association of Women in Communications and the Alliance for Women in Media. Ann reports regularly on science and technology in Focus on Technology.