The UA will receive part of a $9 million federal contract to research the citrus greening disease that is harming the nation's citrus industry and keeping Arizona's industry on guard.

Professor Judith Brown of the UA's School of Plant Sciences will lead the research conducted in Arizona, where the disease hasn't been seen so far - although the bug that spreads it has been detected in western counties.

The research will look for ways to prevent and halt the spread of huanglongbing (HLB), also known as citrus greening disease. The disease has no cure, and once a tree is infected it will die.

The disease is carried and spread by the Asian citrus psyllid, an insect no bigger than a grain of rice. Since the Asian citrus psyllid is banned and under quarantine, Brown's team uses the potato psyllid to conduct similar research. The labs are a contained and controlled environment.

The University of Arizona is collaborating with a lab at Washington State University. The universities combined receive about $1 million of the contract from the U.S. Agriculture Department. The other $8 million is divided among research teams in Florida, Texas and California, Brown said.

"Citrus in Florida has been absolutely devastated by the introduction to the citrus greening disease and the Asian citrus psyllid," said John Caravetta, associate director of the Arizona Department of Agriculture.

Germ undetected in Arizona

Arizona is fortunate not to have detected the disease, unlike other states, Caravetta said.

The citrus industry adds at least $37 million to Arizona's economy each year, he said.

Parts of Texas, California, Florida and Georgia have all detected HLB and the Asian citrus psyllid, the U.S. Agriculture Department says.

Brown said Arizona was the last of the Sun Belt states in which the Asian citrus psyllid was found. However, the bacteria that result in the citrus greening disease have not been detected.

Nursery optimistic

Parts of Arizona where the psyllid has been detected include Yuma County, Bullhead City and Lake Havasu City.

The southwest portion of Yuma County had previously been under quarantine, but with the newer discoveries in Lake Havasu, the quarantine has expanded to include a 20-mile area around Lake Havasu City.

Whitfill Nursery has been growing citrus in Arizona since 1946, and currently grows commercial and nursery products. Owner Brian Blake said that despite the psyllid threat, the company is optimistic.

Blake said Whitfill plans to add 160 acres onto its existing crops in Yuma County and Pinal County. Those crops are outside of the quarantine area.

"We certainly don't want to get the psyllid introduced to our farm," he said. "We want to try to protect it as much as we can."

Blake said the citrus pickers who work at the farms are provided with clean equipment to prevent the spread of the psyllid. Also, machines are sterilized before they are allowed on the fields.

Customers are not really attuned to the citrus problem the industry is facing, Blake said. He said he hasn't spoken with customers about the psyllid because he doesn't want to spread paranoia.

Industry growers depend on Caravetta and the state's Agriculture Department to keep them informed, Blake said. "The more information we have, the more we know, the more we can protect ourselves," he said.

With the recent detection in Lake Havasu City and Bullhead City, the threat is increasing, Caravetta said.

"The problem has gotten worse in Arizona. Although it is still isolated," he said, "we still face significant threats from surrounding states and the situation in our own state." Brown's research will help, he said.

As Brown puts it, "Our job is to look out for Arizona agriculture."


Arizonans are asked not to move citrus trees or their trimmings from an area where the psyllid has been found - such as another state or certain portions of Western Arizona - to places the insect hasn't been detected. For more information call the state Agriculture Department at (602) 542-0955.

Ashley Grove is a NASA Space Grant intern at the University of Arizona. Contact her at or 573-4674.