Analyzing Volatile Organic Compounds to Detect HLB

Kayla MercerCitrus, Citrus Greening

Fresh Oranges on a tree.

Another early detection and screening process for HLB has been developed at the University of California, Davis. Cristina Davis, professor of mechanical and aerospace engineering, is using volatile organic compounds (VOCs) as indicators of disease in trees.

VOCs are odors that are emitted by all living things. These odors can be very meaningful, because they are distinctively different between a healthy tree and an infected tree.

The odors are collected by special instruments, the size of a Tic Tac, called twisters. A twister is hung from a tree canopy for two hours and then taken to the lab for analyzing. Through mass spectrometry analysis, a chemical profile is developed and information can be used as a diagnostic tool. This collection system is reusable, making it more economically feasible as it can be used for multiple tests.

VOCs are not only being used for HLB detection. A pilot program is being developed to utilize this tool for other diseases in agriculture and ornamentals. Tests are being done on rhododendrons, specifically for phytophthora root rot. If testing occurred at the nursery prior to distribution, pathogens could be isolated and quarantined before they spread.

The University of California is supportive of the idea of research not stopping at the lab and allowing faculty spinoffs of research to turn into companies, making these tests available for purchase and application in the field. The development of these companies is still in the early stages, but moving forward to hopefully make tests available to growers.

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