Abstract
Citrus huanglongbing (HLB) is extremely difficult to control because the psyllid-transmitted bacterial pathogen resides inside the citrus phloem and the disease is systemic. In Florida, the nine billion dollar citrus industry has been significantly impacted by severe HLB epidemics. To combat citrus HLB, in this study we implemented an integrated strategy that includes chemotherapy, thermotherapy, and additional nutrition treatment in three different field trials over three consecutive years. In these trials, only trees already showing HLB symptoms with Ct values ranging from 25.1 to 27.7 were selected for treatments. To assess the complex interactions, we used several methods for evaluating the effectiveness of integrated management, including the slopes (b) of the Ct increase (dy/dt), the pathogenic index (PI) and the decline index (DI) from Ct value and tree scores, and the therapeutic efficacies from PI and DI. This comprehensive analysis showed that most of the tested chemicals were effective to some degree in killing or suppressing the Las bacterium, with higher therapeutic efficacies seen for Grove B, where citrus trees were severely affected by HLB, and it had a higher number of psyllids, relative to Grove E and P in the first 2 years. Trunk-injected penicillin G potassium was the most effective chemical treatment in all groves, followed by Oxytetracycline Calcium Complex, and Silver Nitrate delivered as foliar sprays. Although the steam heat treatment and additional nutrition did not eliminate or suppress Las over the long term, these treatments did positively affect tree growth and recovery in the short term. Overall, our results provide new insights into HLB control method and strategy for integrated management for HLB epidemic plantations.
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Claims 10
Claim · model-written summary
Most tested chemicals were effective to some degree in killing or suppressing the Las bacterium in HLB-affected citrus trees.
- Treatment
- tested chemicalse3
- Interactor
- Las bacteriume3pathogen
- Outcome
- killing or suppressing the Las bacteriume3
CitrusNot reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Citrus Huanglongbing”
e3“most of the tested chemicals were effective to some degree in killing or suppressing the Las bacterium”
Claim · model-written summary
Therapeutic efficacies were higher in Grove B than in Groves E and P in the first 2 years.
- Outcome
- therapeutic efficaciese4
- Direction
- highere4
- Qualifier
- in the first 2 yearse5
- Comparator
- Grove E and Pe5
- Setting
- Grove Be4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Citrus Huanglongbing”
e4“with higher therapeutic efficacies seen for Grove B”
e5“relative to Grove E and P in the first 2 years”
Claim · model-written summary
Grove B had a higher number of psyllids than Groves E and P.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Citrus Huanglongbing”
e6“it had a higher number of psyllids, relative to Grove E and P”
Claim · model-written summary
Trunk-injected penicillin G potassium was the most effective chemical treatment in all groves.
- Treatment
- Trunk-injected penicillin G potassiume7
- Outcome
- most effective chemical treatmente7
- Direction
- most effectivee7
- Setting
- all grovese7
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Citrus Huanglongbing”
e7“Trunk-injected penicillin G potassium was the most effective chemical treatment in all groves”
Claim · model-written summary
Oxytetracycline Calcium Complex ranked next in effectiveness after penicillin G potassium.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Citrus Huanglongbing”
e0“followed by Oxytetracycline Calcium Complex, and Silver Nitrate delivered as foliar sprays”
Claim · model-written summary
Silver Nitrate delivered as foliar sprays ranked after the penicillin and oxytetracycline treatments.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Citrus Huanglongbing”
e0“followed by Oxytetracycline Calcium Complex, and Silver Nitrate delivered as foliar sprays”
Claim · model-written summary
The steam heat treatment did not eliminate or suppress Las over the long term.
- Treatment
- steam heat treatmente1
- Interactor
- Las
Candidatus Liberibacter asiaticuse1pathogen - Outcome
- eliminate or suppress Lase1
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Citrus Huanglongbing”
e1“the steam heat treatment and additional nutrition did not eliminate or suppress Las over the long term”
Claim · model-written summary
Additional nutrition did not eliminate or suppress Las over the long term.
- Treatment
- additional nutritione1
- Interactor
- LasCandidatus Liberibacter asiaticuse1pathogen
- Outcome
- eliminate or suppress Lase1
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Citrus Huanglongbing”
e1“the steam heat treatment and additional nutrition did not eliminate or suppress Las over the long term”
Claim · model-written summary
The steam heat treatment positively affected tree growth and recovery in the short term.
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Citrus Huanglongbing”
e1“the steam heat treatment and additional nutrition did not eliminate or suppress Las over the long term”
e2“these treatments did positively affect tree growth and recovery in the short term”
Claim · model-written summary
Additional nutrition positively affected tree growth and recovery in the short term.
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Citrus Huanglongbing”
e1“the steam heat treatment and additional nutrition did not eliminate or suppress Las over the long term”
e2“these treatments did positively affect tree growth and recovery in the short term”
The same questions in other papers
heat · growth · CitrusPositive and negative results
1 paper in the same direction as this paper · 2 in the opposite direction
- negative
- no effect
- positive
heat · Candidatus Liberibacter asiaticus · CitrusResults agree
2 papers in the same direction as this paper
- negative
- negative
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.