Abstract
ABSTRACT Fungicide resistance was identified in natural populations of Penicillium digitatum, the causal agent of green mold of citrus, to two of three new postharvest fungicides before their commercial use. Using a new air-sampling method where large populations of the pathogen in citrus packinghouses were exposed to agar plates with a continuous, wide-range fungicide concentration gradient, isolates with reduced sensitivity to fludioxonil or pyrimethanil were obtained. Resistance frequencies to fludioxonil and pyrimethanil were calculated as 9.5 x 10(-7) to 1.5 x 10(-5) and 7.3 x 10(-6) to 6.2 x 10(-5), respectively. No isolates resistant to azoxystrobin were detected. Isolates with reduced sensitivity to fludioxonil or pyrimethanil were also obtained in laboratory selection studies, where high concentrations of conidial mixtures of isolates sensitive to the three fungicides were plated onto agar amended with each fungicide at 10 microg/ml. Isolates obtained from fludioxonil selection plates in laboratory and packinghouse experiments were placed into two categories based on mycelial growth: moderately resistant isolates had 50% effective concentration (EC(50)) values of 0.1 to 0.82 microg/ml and highly resistant isolates had EC(50) values > 1.5 microg/ml. Isolates resistant to pyrimethanil all had EC(50) values >8 microg/ml. Representative isolates of the two categories with reduced sensitivity to fludioxonil varied widely in their virulence and sporulation capacity as measured by the incidence of decay and degree of sporulation on inoculated fruit, respectively, whereas pyrimethanil-resistant isolates were mostly similar to the wild-type isolate. Fungicide sensitivity characteristics for isolates from fludioxonil and pyrimethanil selection plates remained stable after passages on nonamended agar, and disease could not be controlled after treatment with the respective fungicides. Types of fungicide resistance were visualized on thiabendazole- (TBZ) and imazalil-amended selection plates that were exposed in packinghouses where resistance to these fungicides was known to occur. The qualitative, single-site resistance to the benzimidazole TBZ was visualized by two distinct subpopulations in regard to fungicide sensitivity, whereas the quantitative, multi-site resistance to the demethylation inhibitor imazalil was apparent as a continuous density gradient of colonies along the fungicide concentration gradient. Types of resistance could not be assigned to fludioxonil or pyrimethanil because a limited number of resistant colonies was obtained on each plate. Thus, with this new method, we were able to estimate fungicide resistance frequencies as well as characterize and visualize types of resistance within populations of a fungal species. This information will be used to design resistance management strategies for previous and newly registered postharvest fungicides of citrus.
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Claims 15
Claim · model-written summary
Fungicide resistance was identified in natural populations of Penicillium digitatum on citrus to two of three new postharvest fungicides before their commercial use.
- Material
- natural populationse0
- Interactor
- Penicillium digitatum
Penicillium digitatume0pathogen - Outcome
- Fungicide resistancee0
CitrusOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fungicide resistance was identified in natural populations of Penicillium digitatum, the causal agent of green mold of citrus, to two of three new postharvest fungicides before their commercial use”
Claim · model-written summary
Resistance frequency to fludioxonil in Penicillium digitatum on citrus was 9.5 x 10(-7) to 1.5 x 10(-5).
- Interactor
- Penicillium digitatumPenicillium digitatume0pathogen
- Compound
- fludioxonile1
- Outcome
- Resistance frequenciese1
- Value
- 9.5 x 10(-7) to 1.5 x 10(-5)e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fungicide resistance was identified in natural populations of Penicillium digitatum, the causal agent of green mold of citrus, to two of three new postharvest fungicides before their commercial use”
e1“Resistance frequencies to fludioxonil and pyrimethanil were calculated as 9.5 x 10(-7) to 1.5 x 10(-5) and 7.3 x 10(-6) to 6.2 x 10(-5), respectively”
Claim · model-written summary
Resistance frequency to pyrimethanil in Penicillium digitatum on citrus was 7.3 x 10(-6) to 6.2 x 10(-5).
- Interactor
- Penicillium digitatumPenicillium digitatume0pathogen
- Compound
- pyrimethanile1
- Outcome
- Resistance frequenciese1
- Value
- 7.3 x 10(-6) to 6.2 x 10(-5)e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fungicide resistance was identified in natural populations of Penicillium digitatum, the causal agent of green mold of citrus, to two of three new postharvest fungicides before their commercial use”
e1“Resistance frequencies to fludioxonil and pyrimethanil were calculated as 9.5 x 10(-7) to 1.5 x 10(-5) and 7.3 x 10(-6) to 6.2 x 10(-5), respectively”
Claim · model-written summary
No isolates of Penicillium digitatum resistant to azoxystrobin were detected.
- Interactor
- Penicillium digitatumPenicillium digitatume0pathogen
- Compound
- azoxystrobine2
- Outcome
- No isolates resistant to azoxystrobin were detectede2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fungicide resistance was identified in natural populations of Penicillium digitatum, the causal agent of green mold of citrus, to two of three new postharvest fungicides before their commercial use”
e2“No isolates resistant to azoxystrobin were detected”
Claim · model-written summary
The new air-sampling method with a fungicide concentration gradient yielded isolates with reduced sensitivity to fludioxonil or pyrimethanil from citrus packinghouses.
- Interactor
- Penicillium digitatumPenicillium digitatume0pathogen
- Outcome
- isolates with reduced sensitivity to fludioxonil or pyrimethanil were obtainede3
- Setting
- citrus packinghousese3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Schema note from the model: method performance stated without comparator or value
Verbatim
e0“Fungicide resistance was identified in natural populations of Penicillium digitatum, the causal agent of green mold of citrus, to two of three new postharvest fungicides before their commercial use”
e3“Using a new air-sampling method where large populations of the pathogen in citrus packinghouses were exposed to agar plates with a continuous, wide-range fungicide concentration gradient, isolates with reduced sensitivity to fludioxonil or pyrimethanil were obtained”
Claim · model-written summary
Moderately resistant isolates of Penicillium digitatum on citrus, selected on fludioxonil, had EC50 values of 0.1 to 0.82 microg/ml.
- Interactor
- Penicillium digitatumPenicillium digitatume0pathogen
- Compound
- fludioxonile4
- Outcome
- moderately resistant isolates had 50% effective concentratione4
- Value
- 0.1 to 0.82 microg/mle4
- Qualifier
- based on mycelial growthe4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fungicide resistance was identified in natural populations of Penicillium digitatum, the causal agent of green mold of citrus, to two of three new postharvest fungicides before their commercial use”
e4“Isolates obtained from fludioxonil selection plates in laboratory and packinghouse experiments were placed into two categories based on mycelial growth: moderately resistant isolates had 50% effective concentration (EC(50)) values of 0.1 to 0.82 microg/ml”
Claim · model-written summary
Highly resistant isolates of Penicillium digitatum on citrus, selected on fludioxonil, had EC50 values above 1.5 microg/ml.
- Interactor
- Penicillium digitatumPenicillium digitatume0pathogen
- Compound
- fludioxonile4
- Outcome
- highly resistant isolates had EC(50) valuese5
- Value
- > 1.5 microg/mle5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fungicide resistance was identified in natural populations of Penicillium digitatum, the causal agent of green mold of citrus, to two of three new postharvest fungicides before their commercial use”
e4“Isolates obtained from fludioxonil selection plates in laboratory and packinghouse experiments were placed into two categories based on mycelial growth: moderately resistant isolates had 50% effective concentration (EC(50)) values of 0.1 to 0.82 microg/ml”
e5“highly resistant isolates had EC(50) values > 1.5 microg/ml”
Claim · model-written summary
Pyrimethanil-resistant isolates of Penicillium digitatum on citrus had EC50 values above 8 microg/ml.
- Interactor
- Penicillium digitatumPenicillium digitatume0pathogen
- Compound
- pyrimethanile6
- Outcome
- Isolates resistant to pyrimethanil all had EC(50) valuese6
- Value
- >8 microg/mle6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fungicide resistance was identified in natural populations of Penicillium digitatum, the causal agent of green mold of citrus, to two of three new postharvest fungicides before their commercial use”
e6“Isolates resistant to pyrimethanil all had EC(50) values >8 microg/ml”
Claim · model-written summary
Representative fludioxonil-sensitivity-reduced isolates of Penicillium digitatum on citrus varied widely in virulence and sporulation capacity.
- Interactor
- Penicillium digitatumPenicillium digitatume0pathogen
- Compound
- fludioxonile7
- Outcome
- virulence and sporulation capacitye7
- Qualifier
- varied widelye7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fungicide resistance was identified in natural populations of Penicillium digitatum, the causal agent of green mold of citrus, to two of three new postharvest fungicides before their commercial use”
e7“Representative isolates of the two categories with reduced sensitivity to fludioxonil varied widely in their virulence and sporulation capacity as measured by the incidence of decay and degree of sporulation on inoculated fruit, respectively, whereas pyrimethanil-resistant isolates were mostly similar to the wild-type isolate”
Claim · model-written summary
Virulence and sporulation capacity of pyrimethanil-resistant Penicillium digitatum isolates on citrus were mostly similar to the wild-type isolate.
- Interactor
- Penicillium digitatumPenicillium digitatume0pathogen
- Compound
- pyrimethanile7
- Outcome
- virulence and sporulation capacitye7
- Direction
- mostly similare7
- Comparator
- wild-type isolatee7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fungicide resistance was identified in natural populations of Penicillium digitatum, the causal agent of green mold of citrus, to two of three new postharvest fungicides before their commercial use”
e7“Representative isolates of the two categories with reduced sensitivity to fludioxonil varied widely in their virulence and sporulation capacity as measured by the incidence of decay and degree of sporulation on inoculated fruit, respectively, whereas pyrimethanil-resistant isolates were mostly similar to the wild-type isolate”
Claim · model-written summary
Fungicide sensitivity characteristics of isolates selected on fludioxonil and pyrimethanil remained stable after passage on nonamended agar.
- Interactor
- Penicillium digitatumPenicillium digitatume0pathogen
- Compound
- fludioxonil and pyrimethanile2
- Outcome
- Fungicide sensitivity characteristicse2
- Qualifier
- remained stable after passages on nonamended agare2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fungicide resistance was identified in natural populations of Penicillium digitatum, the causal agent of green mold of citrus, to two of three new postharvest fungicides before their commercial use”
e2“Fungicide sensitivity characteristics for isolates from fludioxonil and pyrimethanil selection plates remained stable after passages on nonamended agar”
Claim · model-written summary
Disease on citrus could not be controlled after treatment with the respective postharvest fungicides.
- Treatment
- treatment with the respective fungicidese2
- Interactor
- Penicillium digitatumPenicillium digitatume0pathogen
- Outcome
- diseasee2
- Direction
- could not be controllede2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fungicide resistance was identified in natural populations of Penicillium digitatum, the causal agent of green mold of citrus, to two of three new postharvest fungicides before their commercial use”
e2“disease could not be controlled after treatment with the respective fungicides”
Claim · model-written summary
Qualitative single-site resistance to the benzimidazole TBZ in Penicillium digitatum on citrus was visualized as two distinct subpopulations in fungicide sensitivity.
- Interactor
- Penicillium digitatumPenicillium digitatume0pathogen
- Compound
- TBZe2
- Outcome
- qualitative, single-site resistancee2
- Qualifier
- two distinct subpopulationse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fungicide resistance was identified in natural populations of Penicillium digitatum, the causal agent of green mold of citrus, to two of three new postharvest fungicides before their commercial use”
e2“The qualitative, single-site resistance to the benzimidazole TBZ was visualized by two distinct subpopulations in regard to fungicide sensitivity”
Claim · model-written summary
Quantitative multi-site resistance to imazalil in Penicillium digitatum on citrus appeared as a continuous density gradient of colonies along the fungicide concentration gradient.
- Interactor
- Penicillium digitatumPenicillium digitatume0pathogen
- Compound
- imazalile2
- Outcome
- quantitative, multi-site resistancee2
- Qualifier
- continuous density gradient of coloniese2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fungicide resistance was identified in natural populations of Penicillium digitatum, the causal agent of green mold of citrus, to two of three new postharvest fungicides before their commercial use”
e2“the quantitative, multi-site resistance to the demethylation inhibitor imazalil was apparent as a continuous density gradient of colonies along the fungicide concentration gradient”
Claim · model-written summary
Types of resistance to fludioxonil or pyrimethanil in Penicillium digitatum on citrus could not be assigned, because only a limited number of resistant colonies was obtained on each plate.
- Interactor
- Penicillium digitatumPenicillium digitatume0pathogen
- Compound
- fludioxonil or pyrimethanile2
- Outcome
- Types of resistance could not be assignede2
- Qualifier
- because a limited number of resistant colonies was obtained on each platee2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fungicide resistance was identified in natural populations of Penicillium digitatum, the causal agent of green mold of citrus, to two of three new postharvest fungicides before their commercial use”
e2“Types of resistance could not be assigned to fludioxonil or pyrimethanil because a limited number of resistant colonies was obtained on each plate”
The same questions in other papers
fungicide · Penicillium digitatum · CitrusPositive and negative results
1 paper in the same direction as this paper · 3 in the opposite direction
- positive
- positive
- positive
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See all 5 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.