Pathogen Detection and Monitoring from Induced VOCs of Citrus Varietals

High value fruit and nut crops are a vital component of agricultural productivity in the United States. Almost 80% of this economic sector is located in the Pacific Northwest (Washington and Oregon), California, and the Southeast (Texas and Florida). Orchards and vineyards in these regions provide healthful fruits and nuts to the nation and for export, support local tourism, and generate economic and environmental benefits. However, orchard and vineyard plants are vulnerable to numerous diseases caused by pests and microbial agents, making our food supply susceptible to both naturally-occurring and intentionally-released pathogens. Huanglongbing (HLB) is a pathogen that devastates citrus crops and the citrus industry desperately needs early detection of these infections. However, there are no robust diagnostic tests currently available for early identification of this or other citrus pathogens under field conditions. This proposal directly responds to the need to reduce the impact of plant pathogens and insect pests on citrus crops by developing a means of early detection. Our proposed technology senses and measures the odor signatures that emanate from the leaves of the plant to identify HLB infected trees from healthy trees. The odor signatures are composed of volatile organic compounds (VOCs) with varying abundances that are different between healthy plants and diseased plants and from plants infected by different pathogens. Our prior work has shown that VOC signature identification can be effective at detecting HLB infected trees before the infection is visually apparent and before it can be confirmed by Polymerase Chain Reaction (PCR) analysis. The VOC signature detection technology proposed has been shown to be effective on sweet orange varietals (Hamlin, Valencia and Madame Vinous). The objectives will be to demonstrate that the VOC signature for HLB infection as detected by the EZKnowz tool is robust against background variations, evaluate the HLB VOC "fingerprint" across many citrus varietals, and optimize the EZKnowz instrument for performance optimization in urban areas and in commercial orchards. Anticipated Results and Potential Commercial Applications: The Phase I efforts will provide the information needed to build the engineering prototype instrument for economical use in commercial orchards and urban landscapes. The Phase II effort will demonstrate economic viability by developing a tool that will be sensitive to the HLB signature and sufficiently fast such that it can be useful beyond academic research. The technical benefit will be a deeper understanding of the response of plants to HLB infections across many citrus varieties. The economic benefit will be a tool that can be used in finding and managing HLB infestations in citrus trees. In Florida, the study by Hodges and Spreen estimates the difference between the scenarios with- versus without-HLB is a total output impact of & #8722;$4.541 billion, total value added of & #8722;$2.717 billion, total labor income of & #8722;$1.753 billion, and average total employment of & #8722;8,257 jobs. The impact of a similar infestation in California would likely be larger.