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Effects of Weather Variables on Ascospore Discharge from Fusarium graminearum Perithecia.

Manstretta V, Rossi V - PLoS ONE (2015)

Bottom Line: To separate the effect of weather on discharge from the effect of weather on the production and maturation of ascospores in perithecia, discharge was quantified with a volumetric spore sampler placed near maize stalk residues bearing perithecia with mature ascospores; the residues therefore served as a continuous source of ascospores.Numbers of ascospores in peaks were best predicted by wetness duration of the previous day, minimum temperature, and VPD, with R2 = 0.71.These results will help refine the epidemiological models used as decision aids in FHB management programs.

View Article: PubMed Central - PubMed

Affiliation: Department of Sustainable Crop Production, Università Cattolica del Sacro Cuore, Piacenza, Italy.

ABSTRACT
Fusarium graminearum is a predominant component of the Fusarium head blight (FHB) complex of small grain cereals. Ascosporic infection plays a relevant role in the spread of the disease. A 3-year study was conducted on ascospore discharge. To separate the effect of weather on discharge from the effect of weather on the production and maturation of ascospores in perithecia, discharge was quantified with a volumetric spore sampler placed near maize stalk residues bearing perithecia with mature ascospores; the residues therefore served as a continuous source of ascospores. Ascospores were discharged from perithecia on 70% of 154 days. Rain (R) and vapor pressure deficit (VPD) were the variables that most affected ascospore discharge, with 84% of total discharges occurring on days with R≥0.2 mm or VPD≤11 hPa, and with 70% of total ascospore discharge peaks (≥ 30 ascospores/m3 air per day) occurring on days with R≥0.2 mm and VPD≤6.35 hPa. An ROC analysis using these criteria for R and VPD provided True Positive Proportion (TPP) = 0.84 and True Negative Proportion (TNP) = 0.63 for occurrence of ascospore discharge, and TPP = 0.70 and TNP = 0.89 for occurrence of peaks. Globally, 68 ascospores (2.5% of the total ascospores sampled) were trapped on the 17 days when no ascospores were erroneously predicted. When a discharge occurred, the numbers of F. graminearum ascospores sampled were predicted by a multiple regression model with R2 = 0.68. This model, which includes average and maximum temperature and VPD as predicting variables, slightly underestimated the real data and especially ascospore peaks. Numbers of ascospores in peaks were best predicted by wetness duration of the previous day, minimum temperature, and VPD, with R2 = 0.71. These results will help refine the epidemiological models used as decision aids in FHB management programs.

No MeSH data available.


Related in: MedlinePlus

ROC curve.Sensitivity vs. 1-Specificity (ROC curve) in predicting discharge (line) and peaks (dotted line) of Fusarium graminearum ascospores as affected by different cut-off points for the number of hours per day with vapor pressure deficit (hPa) ≤ the cut-off point at the University of Piacenza (North Italy) in 2012 to 2014. Points and numbers inside the plot are the best cut-off points.
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pone.0138860.g003: ROC curve.Sensitivity vs. 1-Specificity (ROC curve) in predicting discharge (line) and peaks (dotted line) of Fusarium graminearum ascospores as affected by different cut-off points for the number of hours per day with vapor pressure deficit (hPa) ≤ the cut-off point at the University of Piacenza (North Italy) in 2012 to 2014. Points and numbers inside the plot are the best cut-off points.

Mentions: The ROC analysis showed that VPD was the best meteorological variable for predicting both ascospore trapping (AUROC = 0.799 ± 0.036; P < 0.001) and ascospore peaks (AUROC = 0.849 ± 0.036; P < 0.001) (Table 2); the best cut-off points for the two ROC curves were VPD ≤ 11 and ≤ 6.35 hPa, respectively (Fig 3). Maximum and average daily temperature resulted in AUROC values > 0.7, while use of RH, WD, or numbers of hours with RH > 90% resulted in AUROC values < 0.3 (Table 3).


Effects of Weather Variables on Ascospore Discharge from Fusarium graminearum Perithecia.

Manstretta V, Rossi V - PLoS ONE (2015)

ROC curve.Sensitivity vs. 1-Specificity (ROC curve) in predicting discharge (line) and peaks (dotted line) of Fusarium graminearum ascospores as affected by different cut-off points for the number of hours per day with vapor pressure deficit (hPa) ≤ the cut-off point at the University of Piacenza (North Italy) in 2012 to 2014. Points and numbers inside the plot are the best cut-off points.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4581667&req=5

pone.0138860.g003: ROC curve.Sensitivity vs. 1-Specificity (ROC curve) in predicting discharge (line) and peaks (dotted line) of Fusarium graminearum ascospores as affected by different cut-off points for the number of hours per day with vapor pressure deficit (hPa) ≤ the cut-off point at the University of Piacenza (North Italy) in 2012 to 2014. Points and numbers inside the plot are the best cut-off points.
Mentions: The ROC analysis showed that VPD was the best meteorological variable for predicting both ascospore trapping (AUROC = 0.799 ± 0.036; P < 0.001) and ascospore peaks (AUROC = 0.849 ± 0.036; P < 0.001) (Table 2); the best cut-off points for the two ROC curves were VPD ≤ 11 and ≤ 6.35 hPa, respectively (Fig 3). Maximum and average daily temperature resulted in AUROC values > 0.7, while use of RH, WD, or numbers of hours with RH > 90% resulted in AUROC values < 0.3 (Table 3).

Bottom Line: To separate the effect of weather on discharge from the effect of weather on the production and maturation of ascospores in perithecia, discharge was quantified with a volumetric spore sampler placed near maize stalk residues bearing perithecia with mature ascospores; the residues therefore served as a continuous source of ascospores.Numbers of ascospores in peaks were best predicted by wetness duration of the previous day, minimum temperature, and VPD, with R2 = 0.71.These results will help refine the epidemiological models used as decision aids in FHB management programs.

View Article: PubMed Central - PubMed

Affiliation: Department of Sustainable Crop Production, Università Cattolica del Sacro Cuore, Piacenza, Italy.

ABSTRACT
Fusarium graminearum is a predominant component of the Fusarium head blight (FHB) complex of small grain cereals. Ascosporic infection plays a relevant role in the spread of the disease. A 3-year study was conducted on ascospore discharge. To separate the effect of weather on discharge from the effect of weather on the production and maturation of ascospores in perithecia, discharge was quantified with a volumetric spore sampler placed near maize stalk residues bearing perithecia with mature ascospores; the residues therefore served as a continuous source of ascospores. Ascospores were discharged from perithecia on 70% of 154 days. Rain (R) and vapor pressure deficit (VPD) were the variables that most affected ascospore discharge, with 84% of total discharges occurring on days with R≥0.2 mm or VPD≤11 hPa, and with 70% of total ascospore discharge peaks (≥ 30 ascospores/m3 air per day) occurring on days with R≥0.2 mm and VPD≤6.35 hPa. An ROC analysis using these criteria for R and VPD provided True Positive Proportion (TPP) = 0.84 and True Negative Proportion (TNP) = 0.63 for occurrence of ascospore discharge, and TPP = 0.70 and TNP = 0.89 for occurrence of peaks. Globally, 68 ascospores (2.5% of the total ascospores sampled) were trapped on the 17 days when no ascospores were erroneously predicted. When a discharge occurred, the numbers of F. graminearum ascospores sampled were predicted by a multiple regression model with R2 = 0.68. This model, which includes average and maximum temperature and VPD as predicting variables, slightly underestimated the real data and especially ascospore peaks. Numbers of ascospores in peaks were best predicted by wetness duration of the previous day, minimum temperature, and VPD, with R2 = 0.71. These results will help refine the epidemiological models used as decision aids in FHB management programs.

No MeSH data available.


Related in: MedlinePlus