Citrus greening disease or HLB has become one of the greatest threats to the citrus industry around the world. It is a devastating disease for which no cure has been found, and it spreads quickly through an infected area. The disease has 
ravaged Florida’s citrus groves, and has been found in California. But finally there is some good news. Scientists from the University of California have taken a giant step toward getting this threat under control.
Early detection is vital so infected trees can be treated or removed before the disease spreads throughout the grove. But the disease doesn’t show itself until it is well along, and early detection has not been possible – until now.
A team led by UC Professor Cristina Davis has figured out how to detect HLB diseased citrus at an early stage in the disease cycle. The scientists have built a new lab which can tell growers if their trees are infected. It’s a quick and cost-effective way to detect HLB in a citrus grove.
The process utilizes early detection of the VOCs released by diseased plants. Professor Davis explains that Volatile Organic Compounds are chemicals that join together to make up signature odors – such as the smell of orange blossoms or the pungent odor of garlic. An HLB infected tree has a specific scent to it, but this signature odor is well below human detection. The UC scientists developed a collection device that anyone can use to collect a sample, which is then analyzed for the signature VOCs.
Davis
The process for the grower is simple, according to the Professor. Growers will contact their new lab (XTB Laboratories, at Davis, phone 530-754-9004) and request a test kit. The kit is a collection device which the grower places in a tree. Collection is automatic, and the grower ships the collector back to the lab for testing. The lab will have an answer for the grower within a matter of days.
Professor Davis, who is the head of the UC Davis Bioinstrumentation and BioMEMS Laboratory, started working on identifying HLB VOCs in 2008. Then, testing proved the concept. They conducted tests over 4 growing seasons and found consistent patterns which they could use to identify HLB infected trees.
She says that their workers tested in lemons, Valencia, and grapefruit, in Texas, Florida and California. The team conducted tests in the field and the greenhouses. They found that the signal changed over time but they could still lock in on it. After numerous field trials, they proved they could identify HLB 90 per cent of the time.
For more information contact Professor Davis at XTB Laboratories, in Davis, phone 530-754-9004.
I’m Len Wilcox, and that’s the Western View from AgNet West, brought to you by Citrus Industry Magazine. Check us out on the web at www.citrusindustry.net.