Progress on the development of a field-use optical sensor for screening of citrus pathogens in California

Authors: EDWARDS, PERRY - Croptix; OCHOCHI, BRAD - Croptix; LIU, ZHIWEN - Pennsylvania State University; HAJERI, SUBHAS - Central California Tristeza Eradication Agency; Yokomi, Raymond - Ray

Submitted to: International Research Conference on Huanglongbing
Publication Type: Abstract Only
Publication Acceptance Date: 2/8/2019
Publication Date: 3/10/2019
Citation: Edwards, P., Ochochi, B., Liu, Z., Hajeri, S., Yokomi, R.K. 2019. Progress on the development of a field-use optical sensor for screening of citrus pathogens in California. International Research Conference on Huanglongbing. p. 4-57.

Interpretive Summary:

Technical Abstract: A compact, field-use optical sensor to detect plant disease status was evaluated. The sensor clips to leaves and uses broadband visible and near-infrared light to examine leaves internally to assess physiological changes associated with specific plant health conditions. The spectral data are processed using machine learning analytics and is trained on spectral profiles collected from leaves of citrus trees associated with specific disease or healthy states. The sensor platform can be used as an early screening tool for citrus diseases including ‘Candidatus Liberibacter asiaticus’ (CLas) associated with Huanglongbing (HLB). The sensor is currently being trained on field trees infected with Citrus tristeza virus (CTV) and Spiroplasma citri, causal agent of citrus stubborn disease, in commercial groves in California. These pathogens are phloem-limited, as is CLas, and produce symptoms in citrus that can be confused for HLB. These data will facilitate sensor calibration to distinguish internal spectral profiles of asymptomatic CLas-infected citrus leaves as different from spectral profiles of CTV- and S. citri-infected leaves. Progress on data collection and training efforts with the sensor as a California citrus disease screening tool will be presented.