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ARS Home » Pacific West Area » Parlier, California » San Joaquin Valley Agricultural Sciences Center » Crop Diseases, Pests and Genetics Research » Research » Publications at this Location » Publication #409182
Research Project: Identifying Vulnerabilities in Vector-host-pathogen Interactions of Grapevine and Citrus Pathosystems to Advance Sustainable Management Strategies

Location: Crop Diseases, Pests and Genetics Research

Title: Alternative tissue sampling for improved detection of Candidatus Liberibacter asiaticus

Author
item HAJERI, SUBHAS - Central California Tristeza Eradication Agency
item OLKOWSKI, SANDRA - University Of California, Davis
item KUMAGAI, LUCITA - California Department Of Food And Agriculture
item MCROBERTS, NEIL - University Of California, Davis
item Yokomi, Raymond

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 11/4/2023
Publication Date: 3/26/2024
Citation: Hajeri, S., Olkowski, S., Kumagai, L., Mcroberts, N., Yokomi, R.K. 2024. Alternative tissue sampling for improved detection of Candidatus Liberibacter asiaticus. Meeting Abstract. Presented at the International Research Conference on Huanglongbing VII, on March 26-29, 2024 in Riverside, California.

Interpretive Summary:

Technical Abstract: Early detection and prompt response are key factors in the eradication of "huanglongbing” (HLB) in California. Currently, qPCR testing of leaf tissue guides California Department of Food and Agriculture (CDFA) removal of infected trees. However, because of the uneven distribution of ‘Candidatus Liberibacter asiaticus’ (CLas) in an infected tree and asymptomatic infection, selecting the best leaves to sample, from a mature tree with more than 200,000 estimated leaves, is a major hurdle for timely detection. The goal of this study was to address this issue by testing alternative tissues that might improve the CLas detection rate. Using two years of field data, old and young leaves, peduncle bark of fruit, and feeder roots were evaluated for the presence of CLas. Quadrant-peduncle (Q-P) tissue sampling consistently resulted in better CLas detection than any other tissue type. Q-P samples had a 30% higher qPCR positivity rate than quadrant-leaf (Q-L) samples. No significant seasonal patterns were observed. Roots and single-peduncles had similar detection rates; both were higher than single leaves or Q-L samples. If symptoms were used to guide sampling, 30% of infected trees would have been missed. Based on these findings, CDFA has implemented alternative sampling procedure by including fruit peduncle and feeder roots as part of routine sampling and shown significant improvement in finding CLas-positive trees. The impact of improved sampling on the epidemiology of HLB are discussed.