Abstract
Huanglongbing (HLB), caused by 'Candidatus Liberibacter' spp. and transmitted by the Asian citrus psyllid Diaphorina citri (ACP), is an important threat to citrus industries worldwide, causing significant yield loss. The current recommended strategies to manage HLB are to eliminate HLB-symptomatic trees to reduce sources of bacterial inoculum and to apply insecticides to reduce psyllid vector populations. The objective of this study was to assess the effectiveness and the importance of both strategies applied within young citrus plots (local management), in different frequencies and combinations, on HLB temporal progress. Two factorial field experiments, E1 and E2, were initiated in a new plantation of sweet orange in an HLB epidemic region of Sao Paulo, Brazil, in October 2005 and May 2006, respectively. Local inoculum reduction (tree removal) intervals for E1 were every 4, 8, and 16 weeks and, for E2, every 2, 4, 12, and 26 weeks. Local vector control strategies for E1 were no control, program A (PA), and program B (PB); and, for E2, no control and program C (PC), as follows. Psyllids were controlled with two 56-day-interval soil or drench applications of systemic insecticides concurrently with the rainy season each year and, during the rest of the year, with insecticide sprays every 28 days for PA and every 14 days for PB and PC. Regional HLB management was present for E1 and absent for E2. The beginning of the HLB epidemic was delayed for 10 months in E1 compared with appearance of the first diseased tree in E2 but wasn't affected by different local strategies in either experiment. After 60 (E1) and 53 (E2) months, the HLB incidence and progress rates were not affected by different frequencies of local inoculum reduction in either experiment, and were different only in plots with and without local vector control in E2. In E1, the disease incidence was reduced by 90% and the disease progress rate by 50% in plots both with and without vector control. These reductions were explained by smaller psyllid populations and lower frequency of bacterialiferous psyllids in E1 compared with E2. Annual productivity increased over time in E1, as expected for young plantings, but remained stable or decreased in E2. These results confirm that immigration of bacterialiferous ACP vectors plays a critical role in HLB epidemics and suggest that area-wide inoculum reduction and ACP management strongly affect HLB control.
Abstract from the paper’s OpenAlex record; open copy licensed other-oa. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 11
Claim · model-written summary
The start of the HLB epidemic was 10 months later in E1 than E2.
- Taxon
- sweet orange
Citrus sinensist0 - Outcome
- beginning of the HLB epidemice0
- Direction
- delayede0
- Value
- 10 monthse0
- Comparator
- E2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The beginning of the HLB epidemic was delayed for 10 months in E1 compared with appearance of the first diseased tree in E2”
t0“Sweet Orange”
Claim · model-written summary
Local management strategies did not change epidemic onset in either experiment.
- Taxon
- sweet orangeCitrus sinensist0
- Treatment
- different local strategiese0
- Direction
- wasn't affectede0
Not reportedComparatorOutcome
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“wasn't affected by different local strategies in either experiment”
t0“Sweet Orange”
Claim · model-written summary
Different local inoculum reduction frequencies did not affect HLB incidence.
- Taxon
- sweet orangeCitrus sinensist0
- Treatment
- different frequencies of local inoculum reductione0
- Outcome
- HLB incidencee0
- Direction
- not affectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the HLB incidence and progress rates were not affected by different frequencies of local inoculum reduction in either experiment”
t0“Sweet Orange”
Claim · model-written summary
Different local inoculum reduction frequencies did not affect HLB progress rates.
- Taxon
- sweet orangeCitrus sinensist0
- Treatment
- different frequencies of local inoculum reductione0
- Outcome
- progress ratese0
- Direction
- not affectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the HLB incidence and progress rates were not affected by different frequencies of local inoculum reduction in either experiment”
t0“Sweet Orange”
Claim · model-written summary
HLB incidence differed between plots with and without local vector control in E2.
- Taxon
- sweet orangeCitrus sinensist0
- Treatment
- local vector controle0
- Outcome
- HLB incidencee0
- Qualifier
- E2e0
- Comparator
- without local vector controle0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the HLB incidence and progress rates were not affected by different frequencies of local inoculum reduction in either experiment, and were different only in plots with and without local vector control in E2”
t0“Sweet Orange”
Claim · model-written summary
E1 disease incidence was reduced by 90%.
- Taxon
- sweet orangeCitrus sinensist0
- Outcome
- disease incidencee0
- Direction
- reducede0
- Value
- 90%e0
- Qualifier
- plots both with and without vector controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In E1, the disease incidence was reduced by 90% and the disease progress rate by 50% in plots both with and without vector control.”
t0“Sweet Orange”
Claim · model-written summary
E1 disease progress rate was reduced by 50%.
- Taxon
- sweet orangeCitrus sinensist0
- Outcome
- disease progress ratee0
- Direction
- reducede0
- Value
- 50%e0
- Qualifier
- plots both with and without vector controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In E1, the disease incidence was reduced by 90% and the disease progress rate by 50% in plots both with and without vector control.”
t0“Sweet Orange”
Claim · model-written summary
Psyllid populations were smaller in E1 than E2.
- Taxon
- sweet orangeCitrus sinensist0
- Interactor
- psyllidsPsylloideae0pest
- Outcome
- psyllid populationse0
- Direction
- smallere0
- Comparator
- E2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“smaller psyllid populations and lower frequency of bacterialiferous psyllids in E1 compared with E2”
t0“Sweet Orange”
Claim · model-written summary
Frequency of bacterialiferous psyllids was lower in E1 than E2.
- Taxon
- sweet orangeCitrus sinensist0
- Interactor
- psyllidsPsylloideae0pest
- Outcome
- frequency of bacterialiferous psyllidse0
- Direction
- lowere0
- Comparator
- E2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“smaller psyllid populations and lower frequency of bacterialiferous psyllids in E1 compared with E2”
t0“Sweet Orange”
Claim · model-written summary
Annual productivity increased over time in E1.
- Taxon
- sweet orangeCitrus sinensist0
- Outcome
- Annual productivitye0
- Direction
- increasede0
- Qualifier
- E1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Annual productivity increased over time in E1”
t0“Sweet Orange”
Claim · model-written summary
Annual productivity remained stable or decreased in E2.
- Taxon
- sweet orangeCitrus sinensist0
- Outcome
- Annual productivitye0
- Direction
- decreasede0
- Qualifier
- E2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Annual productivity increased over time in E1, as expected for young plantings, but remained stable or decreased in E2.”
t0“Sweet Orange”
The same questions in other papers
inoculation · disease · Citrus sinensis (sweet orange)Positive and negative results
9 papers in the same direction as this paper · 5 in the opposite direction
- positive
- positive
- positive
11 papers more in this group
See all 15 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.