Seasonality of Ct Values in CA plant samples

In other citrus-growing regions of the world, distinct annual patterns of Ct value variability have been observed. Management plans in CA were based on the assumption that similar patterns would occur, but no analysis had been completed to validate the assumption.
Project Timeline

Open the 2020 report:

Open the 2019 report:

September 2, 2020

DATOC produced an update  to our prior report. There are still no signficiant seasonal patterns in CLas titers in HLB+ trees in residential areas of Southern California.

cn by season ridge plot.png

June 12, 2019

DATOC finalized analysis and presented the results to a joint meeting of the CPDPP Science & Technology and Operations Subcommittees.  DATOC found no significant differences in Ct values by the season the plant sample was collected, and suggested that on the basis of the likelihood of disease detection, biennial sample of commercial groves was not justified. The CPDPP voted to approve the report and its accompanying recommendations. 

mean ct value plants.png

April 2019

DATOC begins internal deliberations and analysis on the cost and efficacy of biennial sampling.

ave ct value of plant samples by month c

March 12, 2019

The CPDPC voted to approve DATOC's advisory briefing entitled "Recommendation for CDFA Regulatory Response to a Huanglongbing Detection Near Commercial Citrus", which included a suggestion for biennial sampling of commercial groves near 400 m of an HLB detection, based on seasonal variability of Ct values seen in other growing regions. 

hypothetical sample zone (2).png