Abstract
Quinone outside inhibitor (QoI) and succinate dehydrogenase inhibitor (SdhI) fungicides are respiration inhibitors (RIs) used for preharvest control of brown rot of stone fruit. Both chemical classes are site-specific and, thus, prone to resistance development. Between 2006 and 2008, 157 isolates of Monilinia fructicola collected from multiple peach and nectarine orchards with or without RI spray history in South Carolina and Georgia were characterized based upon conidial germination and mycelial growth inhibition for their sensitivity to QoI fungicides azoxystrobin and pyraclostrobin, SdhI fungicide boscalid, and a mixture of pyraclostrobin + boscalid. There was no significant difference (P = 0.05) between EC 50 values for inhibition of conidial germination versus mycelial growth. The mean EC 50 values based upon mycelial growth tests for 25 isolates from an orchard without RI-spray history were 0.15, 0.06, 2.23, and 0.09 μg/ml for azoxystrobin, pyraclostrobin, boscalid, and pyraclostrobin + boscalid, respectively. The respective mean EC 50 values for 76 isolates from RI-sprayed orchards in South Carolina were 0.9, 0.1, 10.7, and 0.13 μg/ml and for 56 isolates from RI-sprayed orchards in Georgia were 1.2, 0.1, 8.91, and 0.17 μg/ml. Overall, mean EC 50 values of populations from RI-sprayed orchards increased three-, two-, five-, and twofold between 2006 and 2008 for azoxystrobin, pyraclostrobin, boscalid, and pyraclostrobin + boscalid, respectively. A subset of 10 M. fructicola isolates representing low and high EC 50 values for azoxystrobin, boscalid, and boscalid + pyraclostrobin was selected for a detached fruit assay to determine disease incidence and severity following protective treatments of formulated RI fungicides at label rates. Brown rot incidence was greater than 50% when fruit were inoculated with isolates having EC 50 values of 2, 4, and 0.6 μg/ml for azoxystrobin, boscalid, and pyraclostrobin + boscalid, respectively. Pyraclostrobin failed to control any of the isolates tested in detached fruit assays. Based on minimum inhibitory concentration and brown rot incidence data, we recommend using 3 and 0.75 μg/ml as discriminatory doses to distinguish between sensitive isolates and those with reduced sensitivity to azoxystrobin and pyraclostrobin + boscalid, respectively. Results from our in vitro and in vivo assays indicate a shift toward reduced sensitivity in M. fructicola from the southeastern United States. No cross-resistance was observed between the QoI and the SdhI fungicides, which implies that rotation or tank mixtures of these two chemical classes can be used as a resistance management strategy.
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Claims 12
Claim · model-written summary
Conidial germination and mycelial growth inhibition gave no significant difference in EC 50 estimates.
- Taxon
- peach and nectarine
Prunus persicaPrunus persica var. nucipersicae0 - Interactor
- Monilinia fructicola
Monilinia fructicolat0pathogen - Outcome
- EC 50 values for inhibition of conidial germination versus mycelial growthe1
- Direction
- no significant differencee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“peach and nectarine orchards”
e1“There was no significant difference (P = 0.05) between EC 50 values for inhibition of conidial germination versus mycelial growth”
t0“Monilinia fructicola”
Claim · model-written summary
Azoxystrobin EC 50 was 0.15 μg/ml in an unsprayed orchard, 0.9 in South Carolina sprayed orchards, and 1.2 in Georgia sprayed orchards.
- Taxon
- peach and nectarinePrunus persicaPrunus persica var. nucipersicae0
- Interactor
- Monilinia fructicolaMonilinia fructicolat0pathogen
- Outcome
- EC 50 valuese1
- Value
- 0.15e1
- Qualifier
- azoxystrobine1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“peach and nectarine orchards”
e1“The mean EC 50 values based upon mycelial growth tests for 25 isolates from an orchard without RI-spray history were 0.15, 0.06, 2.23, and 0.09 μg/ml for azoxystrobin, pyraclostrobin, boscalid, and pyraclostrobin + boscalid, respectively”
e2“The respective mean EC 50 values for 76 isolates from RI-sprayed orchards in South Carolina were 0.9, 0.1, 10.7, and 0.13 μg/ml and for 56 isolates from RI-sprayed orchards in Georgia were 1.2, 0.1, 8.91, and 0.17 μg/ml”
t0“Monilinia fructicola”
Claim · model-written summary
Mean EC 50 of azoxystrobin in sprayed orchard populations increased threefold over 2006–2008.
- Taxon
- peach and nectarinePrunus persicaPrunus persica var. nucipersicae0
- Interactor
- Monilinia fructicolaMonilinia fructicolat0pathogen
- Outcome
- mean EC 50 valuese1
- Direction
- increasede1
- Qualifier
- azoxystrobine1
- Setting
- RI-sprayed orchardse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“peach and nectarine orchards”
e1“Overall, mean EC 50 values of populations from RI-sprayed orchards increased three-, two-, five-, and twofold between 2006 and 2008 for azoxystrobin, pyraclostrobin, boscalid, and pyraclostrobin + boscalid, respectively”
t0“Monilinia fructicola”
Claim · model-written summary
Mean EC 50 of pyraclostrobin in sprayed orchard populations increased twofold over 2006–2008.
- Taxon
- peach and nectarinePrunus persicaPrunus persica var. nucipersicae0
- Interactor
- Monilinia fructicolaMonilinia fructicolat0pathogen
- Outcome
- mean EC 50 valuese1
- Direction
- increasede1
- Qualifier
- pyraclostrobine1
- Setting
- RI-sprayed orchardse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“peach and nectarine orchards”
e1“Overall, mean EC 50 values of populations from RI-sprayed orchards increased three-, two-, five-, and twofold between 2006 and 2008 for azoxystrobin, pyraclostrobin, boscalid, and pyraclostrobin + boscalid, respectively”
t0“Monilinia fructicola”
Claim · model-written summary
Mean EC 50 of boscalid in sprayed orchard populations increased fivefold over 2006–2008.
- Taxon
- peach and nectarinePrunus persicaPrunus persica var. nucipersicae0
- Interactor
- Monilinia fructicolaMonilinia fructicolat0pathogen
- Outcome
- mean EC 50 valuese1
- Direction
- increasede1
- Qualifier
- boscalide1
- Setting
- RI-sprayed orchardse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“peach and nectarine orchards”
e1“Overall, mean EC 50 values of populations from RI-sprayed orchards increased three-, two-, five-, and twofold between 2006 and 2008 for azoxystrobin, pyraclostrobin, boscalid, and pyraclostrobin + boscalid, respectively”
t0“Monilinia fructicola”
Claim · model-written summary
Mean EC 50 of pyraclostrobin plus boscalid in sprayed orchard populations increased twofold over 2006–2008.
- Taxon
- peach and nectarinePrunus persicaPrunus persica var. nucipersicae0
- Interactor
- Monilinia fructicolaMonilinia fructicolat0pathogen
- Outcome
- mean EC 50 valuese1
- Direction
- increasede1
- Qualifier
- pyraclostrobin + boscalide1
- Setting
- RI-sprayed orchardse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“peach and nectarine orchards”
e1“Overall, mean EC 50 values of populations from RI-sprayed orchards increased three-, two-, five-, and twofold between 2006 and 2008 for azoxystrobin, pyraclostrobin, boscalid, and pyraclostrobin + boscalid, respectively”
t0“Monilinia fructicola”
Claim · model-written summary
Brown rot incidence exceeded 50% after inoculation with isolates having the specified EC 50 thresholds.
- Taxon
- peach and nectarinePrunus persicaPrunus persica var. nucipersicae0
- Interactor
- Monilinia fructicolaMonilinia fructicolat0pathogen
- Outcome
- Brown rot incidencee1
- Direction
- greater thane1
- Value
- 50%e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“peach and nectarine orchards”
e1“Brown rot incidence was greater than 50% when fruit were inoculated with isolates having EC 50 values of 2, 4, and 0.6 μg/ml for azoxystrobin, boscalid, and pyraclostrobin + boscalid, respectively”
t0“Monilinia fructicola”
Claim · model-written summary
Pyraclostrobin failed to control any tested isolates in detached fruit assays.
- Taxon
- peach and nectarinePrunus persicaPrunus persica var. nucipersicae0
- Treatment
- Pyraclostrobine1
- Interactor
- Monilinia fructicolaMonilinia fructicolat0pathogen
- Outcome
- control any of the isolatese1
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“peach and nectarine orchards”
e1“Pyraclostrobin failed to control any of the isolates tested in detached fruit assays”
t0“Monilinia fructicola”
Claim · model-written summary
The authors recommend 3 μg/ml to distinguish azoxystrobin-sensitive isolates from less sensitive ones.
- Taxon
- peach and nectarinePrunus persicaPrunus persica var. nucipersicae0
- Interactor
- Monilinia fructicolaMonilinia fructicolat0pathogen
- Outcome
- discriminatory doses to distinguish between sensitive isolates and those with reduced sensitivitye1
- Qualifier
- azoxystrobine1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“peach and nectarine orchards”
e1“we recommend using 3 and 0.75 μg/ml as discriminatory doses to distinguish between sensitive isolates and those with reduced sensitivity to azoxystrobin and pyraclostrobin + boscalid, respectively”
t0“Monilinia fructicola”
Claim · model-written summary
The authors recommend 0.75 μg/ml to distinguish pyraclostrobin plus boscalid-sensitive isolates from less sensitive ones.
- Taxon
- peach and nectarinePrunus persicaPrunus persica var. nucipersicae0
- Interactor
- Monilinia fructicolaMonilinia fructicolat0pathogen
- Outcome
- discriminatory doses to distinguish between sensitive isolates and those with reduced sensitivitye1
- Qualifier
- pyraclostrobin + boscalide1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“peach and nectarine orchards”
e1“we recommend using 3 and 0.75 μg/ml as discriminatory doses to distinguish between sensitive isolates and those with reduced sensitivity to azoxystrobin and pyraclostrobin + boscalid, respectively”
t0“Monilinia fructicola”
Claim · model-written summary
No cross-resistance was seen between QoI and SdhI fungicides.
- Taxon
- peach and nectarinePrunus persicaPrunus persica var. nucipersicae0
- Interactor
- Monilinia fructicolaMonilinia fructicolat0pathogen
- Outcome
- cross-resistancee1
- Direction
- Noe1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“peach and nectarine orchards”
e1“No cross-resistance was observed between the QoI and the SdhI fungicides”
t0“Monilinia fructicola”
Claim · model-written summary
The authors suggest rotation or tank mixtures of QoI and SdhI fungicides for resistance management.
- Taxon
- peach and nectarinePrunus persicaPrunus persica var. nucipersicae0
- Interactor
- Monilinia fructicolaMonilinia fructicolat0pathogen
- Outcome
- rotation or tank mixtures of these two chemical classes can be used as a resistance management strategye1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“peach and nectarine orchards”
e1“rotation or tank mixtures of these two chemical classes can be used as a resistance management strategy”
t0“Monilinia fructicola”
The same questions in other papers
pyraclostrobin · Monilinia fructicola · Prunus persica (peach)Positive and negative results
1 in the opposite direction
- positive
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.