Risk-based HLB/ACP Survey for both Residential and Commercial citrus in Argentina, 2018

92 Pages·2017·8.61 MB·English

by  Tim Gottwald

Risk-based HLB/ACP Survey for
both Residential and Commercial
citrus in Argentina, 2018
Tim Gottwald & Weiqi Luo
02/22/2018
Objective: Why do
we need a risk-
based survey?
HLB is spreading in Northeastern Argentina.
HLB Now threatens the Entre Rios region and
all citriculture in Argentina
Risk-based surveys are used broadly in the
USA (California, Texas, Arizona, and Florida)
 Risk-based surveys are based on all known
biotic and abiotic risk factors for early
detection of the pathogen.
Provide a means of early detection and
mitigation (disease suppression).
Topics to be covered
1. What is a risk-based survey: Methods explained to
find and monitor HLB and ACP – Example of
California
2. Survey design for Entre Rios region
3. Early detection methods
4. Sampling uncertainty
5. Early detection of HLB:
a. Issues with PCR explained
b. Alternative early detection methods
California residential citrus Risk-
based HLB/ACP Survey 2018
Tim Gottwald & Weiqi Luo
03/22/2018
Risk-Based Model framework for residential
HLB/ACP risk (model refined each year)
Filtering
Original Census tract
Elevation
Water Land cover
Military
Indian Reservation n
o
i
t
a
r
g
Risk modeling parameters e
t
n
I
Resulting residential area
Population
Weather Citrus transport
& race
Final risk
mapping
ACP- and
(Nursery & Big box store survey
ACP+
Citrus green waste)
protocol
CDFA Data associated with risk-based survey:
qPCR Ct values of assayed citrus trees
Ct range # detects
CDFA Data associated with risk-based survey:
qPCR Ct values of assayed ACP
Fresno
Ct range # detects
28
15
134
683
For each HLB detection, we
trace back the sampling
density to estimate the
sampling efficacy.
HLB progress curve in CA
Number of visit (e.g. sampled locations)
required for each HLB finding, assuming
HLB+ tree has been infected for a year
Number of HLB+ finds by year
Exponential growth
phase for HLB in
South CA??
Formula & algorithm
4. Estimate risk from citrus fruit transport corridor (to packinghouse and juice plants)
•Apply HLB/ACP spread functions determined from Florida data
Major
Major
routes with
routes with
strong
strong
effects on
effects on
HLB
ACP
Full information available: Gottwald & Luo, An investigation of transport network on HLB/ACP spread.