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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

Weather data during the sampling periods.Air temperature (T), relative humidity (RH), and rainfall at the University of Piacenza (North Italy) during the periods in 2012 (A), 2013 (B), and 2014 (C) when Fusarium graminearum ascospores were sampled from the air above maize stalk residues bearing mature perithecia.
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pone.0138860.g001: Weather data during the sampling periods.Air temperature (T), relative humidity (RH), and rainfall at the University of Piacenza (North Italy) during the periods in 2012 (A), 2013 (B), and 2014 (C) when Fusarium graminearum ascospores were sampled from the air above maize stalk residues bearing mature perithecia.

Mentions: The period in which there were mature perithecia on maize stalk residues was 26 days long in 2012, 75 days in 2013, and 53 days in 2014. Weather data measured during these three sampling periods are shown in Fig 1. In 2012, the overall average daily temperature was 15.3°C, with a minimum (min) of 10.1°C and a maximum (max) of 23.6°C; the average daily RH was 72.3%, with a min of 58.0% and a max of 93.8%. Total rainfall was 33.2 mm on 12 rainy days (representing 48% of the total number of days, most rainy days had < 2 mm of rain). In 2013, the average daily temperature during the experiment was higher than in 2012 (18.8°C, min 8.7°C, and max 27.7°C) and RH was lower (69.8%, min 50.3% and max 93.5%); total rainfall was about six-times higher (total of 200.2 mm on 25 rainy days). Several consecutives days without rain (i.e., dry periods) were recorded between the end of May and June in 2013. In 2014, the experiment began later than in the previous years, and the average daily temperature was higher (21.2°C, min 15.7°C, and max 29.2°C) and RH was lower (59.3%, min 31.2%, and max 85.3%); total rainfall was 111.2 mm on 12 rainy days. Dry periods were recorded from day 1 to 21, from day 31 to 39, and from day 44 to 51. Average rain amount per rain event was higher in 2013 and 2014 than in 2012 (8.0, 9.2, and 2.8 mm, respectively). Two rain events with > 30 mm were recorded in 2013 and one in 2014; in 2012, the highest rain amount in 1 day was 16.2 mm.


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

Manstretta V, Rossi V - PLoS ONE (2015)

Weather data during the sampling periods.Air temperature (T), relative humidity (RH), and rainfall at the University of Piacenza (North Italy) during the periods in 2012 (A), 2013 (B), and 2014 (C) when Fusarium graminearum ascospores were sampled from the air above maize stalk residues bearing mature perithecia.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0138860.g001: Weather data during the sampling periods.Air temperature (T), relative humidity (RH), and rainfall at the University of Piacenza (North Italy) during the periods in 2012 (A), 2013 (B), and 2014 (C) when Fusarium graminearum ascospores were sampled from the air above maize stalk residues bearing mature perithecia.
Mentions: The period in which there were mature perithecia on maize stalk residues was 26 days long in 2012, 75 days in 2013, and 53 days in 2014. Weather data measured during these three sampling periods are shown in Fig 1. In 2012, the overall average daily temperature was 15.3°C, with a minimum (min) of 10.1°C and a maximum (max) of 23.6°C; the average daily RH was 72.3%, with a min of 58.0% and a max of 93.8%. Total rainfall was 33.2 mm on 12 rainy days (representing 48% of the total number of days, most rainy days had < 2 mm of rain). In 2013, the average daily temperature during the experiment was higher than in 2012 (18.8°C, min 8.7°C, and max 27.7°C) and RH was lower (69.8%, min 50.3% and max 93.5%); total rainfall was about six-times higher (total of 200.2 mm on 25 rainy days). Several consecutives days without rain (i.e., dry periods) were recorded between the end of May and June in 2013. In 2014, the experiment began later than in the previous years, and the average daily temperature was higher (21.2°C, min 15.7°C, and max 29.2°C) and RH was lower (59.3%, min 31.2%, and max 85.3%); total rainfall was 111.2 mm on 12 rainy days. Dry periods were recorded from day 1 to 21, from day 31 to 39, and from day 44 to 51. Average rain amount per rain event was higher in 2013 and 2014 than in 2012 (8.0, 9.2, and 2.8 mm, respectively). Two rain events with > 30 mm were recorded in 2013 and one in 2014; in 2012, the highest rain amount in 1 day was 16.2 mm.

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