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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

Model prediction.Numbers of Fusarium graminearum ascospores predicted by model (1) (see Table 5) based on average air temperature (Tav), maximum air temperature (Tmax), and vapor pressure deficit (VPD). Average relative humidity (RHav) is shown as a component for calculating VPD. Predicted ascospore numbers are expressed as ln(x+1).
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pone.0138860.g005: Model prediction.Numbers of Fusarium graminearum ascospores predicted by model (1) (see Table 5) based on average air temperature (Tav), maximum air temperature (Tmax), and vapor pressure deficit (VPD). Average relative humidity (RHav) is shown as a component for calculating VPD. Predicted ascospore numbers are expressed as ln(x+1).

Mentions: Based on a stepwise regression procedure, the following variables were selected as being most useful for predicting the number of ascospores sampled (on a ln scale): Ti, Tmaxi, and VPDi. Based on regression model (1) (Table 5), on any day with ascospores (accounted for by the dichotomic variable ASCi), the ascospore number decreased as temperature and VPD of the day increased. Fig 5 shows the numbers of ascospores predicted by the model along with temperature (as both T and Tmax), RH, and VPD on a set of selected days during which temperature increased. Note that the trend in ascospore numbers was opposite to the trends in both temperature and VPD.


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

Manstretta V, Rossi V - PLoS ONE (2015)

Model prediction.Numbers of Fusarium graminearum ascospores predicted by model (1) (see Table 5) based on average air temperature (Tav), maximum air temperature (Tmax), and vapor pressure deficit (VPD). Average relative humidity (RHav) is shown as a component for calculating VPD. Predicted ascospore numbers are expressed as ln(x+1).
© Copyright Policy
Related In: Results  -  Collection

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

pone.0138860.g005: Model prediction.Numbers of Fusarium graminearum ascospores predicted by model (1) (see Table 5) based on average air temperature (Tav), maximum air temperature (Tmax), and vapor pressure deficit (VPD). Average relative humidity (RHav) is shown as a component for calculating VPD. Predicted ascospore numbers are expressed as ln(x+1).
Mentions: Based on a stepwise regression procedure, the following variables were selected as being most useful for predicting the number of ascospores sampled (on a ln scale): Ti, Tmaxi, and VPDi. Based on regression model (1) (Table 5), on any day with ascospores (accounted for by the dichotomic variable ASCi), the ascospore number decreased as temperature and VPD of the day increased. Fig 5 shows the numbers of ascospores predicted by the model along with temperature (as both T and Tmax), RH, and VPD on a set of selected days during which temperature increased. Note that the trend in ascospore numbers was opposite to the trends in both temperature and VPD.

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