Relation of weather variables and host factors to incidence of airborne spores of Bipolaris sorokiniana

1978 ◽  
Vol 56 (17) ◽  
pp. 2162-2170 ◽  
Author(s):  
L. Couture ◽  
J. C. Sutton
Keyword(s):  
High Temperatures ◽  
Bipolaris Sorokiniana ◽  
Weather Variables ◽  
Weather Factors ◽  
Airborne Spores ◽  
Surface Wetness ◽  
Large Numbers ◽  
Spore Release ◽  
Crop Development ◽  
Field Plots

Seasonal and daily incidence of airborne spores of Bipolaris sorokiniana were studied in barley field plots in relation to crop development, disease severity, and weather variables. Sporulation was observed only on dead or senescent barley. The incidence of airborne spores before 8–11 July was low because spore-bearing barley foliage was scarce and weather factors were often unfavourable for sporulation. Large numbers of spores encountered after 8–11 July coincided with rapid disease progress and repeated occurrence of persistent leaf wetness and high temperatures. Cumulative spore counts showed that few spores were dispersed sufficiently early in the growing season to serve as inoculum in the epidemics. Numbers of airborne spores were low at night, but increased abruptly after dawn to peak concentrations during 0900 to 1700 hours. Circumstantial evidence indicated that spore production was promoted by persistent leaf-surface wetness, high relative humidity (RH), and high temperatures (> 15 °C), but restricted by cool temperatures. Correlative studies showed that spore release was caused by rapidly declining RH and wind. Spores were dispersed mostly when the leaves were dry and the numbers dispersed correlated very strongly with wind speed. Few spores were dispersed when leaves were wet and RH high.

Relation of weather variables and host factors to incidence of airborne spores of Botrytis squamosa

1978 ◽  
Vol 56 (20) ◽  
pp. 2460-2469 ◽  
Author(s):  
J. C. Sutton ◽  
C. J. Swanton ◽  
T. J. Gillespie
Keyword(s):  
Spore Production ◽  
Host Factors ◽  
Limiting Factors ◽  
Weather Variables ◽  
Airborne Spores ◽  
Botrytis Squamosa ◽  
Wind Speeds ◽  
Spore Release ◽  
Field Plots ◽  
July Temperature

Weather variables, leaf blight, and airborne spores of Botrytis squamosa were monitored in onion field plots at the Holland–Bradford Marsh, Ontario, in 1976. Incidence of spores showed marked daily periodicities with peaks normally between 0900 and 1200 hours Eastern Standard Time (EST). Daily spore counts were low (< 85 spores) during 7 to 28 July, often high (> 1000 spores) during29 July to 16 August, and moderate (100 to 1000 spores) between 17 and 28 August. Spore production was observed only on necrotic portions of onion leaves. Circumstantial and correlative evidence indicated that spore production was promoted by persistent leaf wetness (> 13 h), high temperatures during wetness periods (14 to 20 °C), and by leaf dieback but was restricted by brief wetness periods [Formula: see text] and by cool temperatures [Formula: see text]. Linear correlation analyses of 2- to 4-day running means of data indicated that important limiting factors in spore production were wetness duration during 7 to 28 July, temperature during 29 July to 28 August, and severity of dieback during 7 July to 16 August. Lodging appeared to suppress incidence of spores after 16 August. Spore release was promoted largely by declining relative humidity (RH) and by rain but occasionally by increasing RH. Striking peaks of airborne spores occurred during rain showers. Spore counts when leaves were dry failed to correlate with wind speed, and many spores were dispersed when wind speeds were low(1 to 4 km/h).

scholarly journals Association Between Weather Variables, Airborne Inoculum Concentration, and Raspberry Fruit Rot Caused by Botrytis cinerea

2018 ◽  
Vol 108 (1) ◽  
pp. 70-82 ◽  
Author(s):  
Odile Carisse ◽  
Vanessa McNealis ◽  
Alissa Kriss
Keyword(s):  
Meteorological Data ◽  
Fruit Rot ◽  
Weather Variables ◽  
Storage Duration ◽  
Inoculum Concentration ◽  
Crop Losses ◽  
Airborne Inoculum ◽  
Average Relative Humidity ◽  
And Storage ◽  
Field Plots

Botrytis fruit rot (BFR), one of the most important diseases of raspberry (Rubus spp.), is controlled primarily with fungicides. Despite the use of fungicides, crop losses due to BFR are high in most years. The aim of this study was to investigate the association between airborne inoculum, weather variables, and BFR in order to improve the management of the disease as well as harvest and storage decisions. Crop losses, measured as the percentage of diseased berries during the harvest period, were monitored in unsprayed field plots at four sites in three successive years, together with meteorological data and the number of conidia in the air. Based on windowpane analysis, there was no evidence of correlation between crop losses and temperature, vapor pressure deficit, wind, solar radiation, or probability of infection. There were significant correlations between crop losses and airborne inoculum and between crop losses and humidity-related variables, and the best window length was identified as 7 days. Using 7-day average airborne inoculum concentration combined with 7-day average relative humidity for periods ending 6 to 8 days before bloom, it was possible to accurately predict crop losses (R2 of 0.86 to 0.89). These models could be used to assist with managing BFR, timing harvests, and optimizing storage duration in raspberry crops.

scholarly journals Statistical Modelling of the Effects of Weather Factors on Malaria Occurrence in Abuja, Nigeria

2020 ◽  
Vol 17 (10) ◽  
pp. 3474 ◽  
Author(s):  
Oguntade Emmanuel Segun ◽  
Shamarina Shohaimi ◽  
Meenakshii Nallapan ◽  
Alaba Ajibola Lamidi-Sarumoh ◽  
Nader Salari
Keyword(s):  
Linear Models ◽  
Negative Binomial ◽  
Malaria Incidence ◽  
Pearson Correlation ◽  
Ecological Factors ◽  
Weather Conditions ◽  
Statistical Modelling ◽  
Weather Variables ◽  
Weather Factors ◽  
Unit Increase

Background: despite the increase in malaria control and elimination efforts, weather patterns and ecological factors continue to serve as important drivers of malaria transmission dynamics. This study examined the statistical relationship between weather variables and malaria incidence in Abuja, Nigeria. Methodology/Principal Findings: monthly data on malaria incidence and weather variables were collected in Abuja from the year 2000 to 2013. The analysis of count outcomes was based on generalized linear models, while Pearson correlation analysis was undertaken at the bivariate level. The results showed more malaria incidence in the months with the highest rainfall recorded (June–August). Based on the negative binomial model, every unit increase in humidity corresponds to about 1.010 (95% confidence interval (CI), 1.005–1.015) times increase in malaria cases while the odds of having malaria decreases by 5.8% for every extra unit increase in temperature: 0.942 (95% CI, 0.928–0.956). At lag 1 month, there was a significant positive effect of rainfall on malaria incidence while at lag 4, temperature and humidity had significant influences. Conclusions: malaria remains a widespread infectious disease among the local subjects in the study area. Relative humidity was identified as one of the factors that influence a malaria epidemic at lag 0 while the biggest significant influence of temperature was observed at lag 4. Therefore, emphasis should be given to vector control activities and to create public health awareness on the proper usage of intervention measures such as indoor residual sprays to reduce the epidemic especially during peak periods with suitable weather conditions.

scholarly journals Natural Occurrence of Maize Gibberella Ear Rot and Contamination of Grain with Mycotoxins in Association with Weather Variables

Plant Disease ◽  
2021 ◽  
Vol 105 (1) ◽  
pp. 114-126 ◽  
Author(s):  
F. Dalla Lana ◽  
L. V. Madden ◽  
P. A. Paul
Keyword(s):  
Correlation Coefficients ◽  
Natural Occurrence ◽  
Spearman Correlation ◽  
Ear Rot ◽  
Weather Variables ◽  
Gibberella Ear Rot ◽  
Maize Hybrids ◽  
Surface Wetness ◽  
Percent Area ◽  
Grain Contamination

Gibberella ear rot (GER) severity (percent area of the ear diseased) and associated grain contamination with mycotoxins were quantified in plots of 15 to 16 maize hybrids planted at 10 Ohio locations from 2015 to 2018. Deoxynivalenol (DON) was quantified in grain samples in all 4 years, whereas nivalenol, 3-acetyldeoxynivalenol, and 15-acetyldeoxynivalenol (15ADON) were quantified only in the last 2 years. Only DON and 15ADON were detected. The highest levels of GER and DON contamination were observed for 2018, followed by 2016 and 2017. No GER symptoms or DON were detected in 2015. Approximately 41% of the samples from asymptomatic ears had detectable levels of DON, and 7% of these samples from 2016 had DON > 5 ppm. Associations between DON contamination and 43 variables representing summaries of temperature (T), relative humidity (RH), rainfall (R), surface wetness, and T-RH combinations for different window lengths and positions relative to R1 growth stage were quantified with Spearman correlation coefficients (r). Fifteen-day window lengths tended to show the highest correlations. Most of the variables based on T, R, RH, and T-RH were significantly correlated with DON for the 15-day window, as well as other windows. For moisture-related variables, there generally was a negative correlation before R1, changing to a positive correlation after R1. Results showed that GER and DON can be frequently found in Ohio maize fields, with the risk of DON being associated with multiple weather variables, particularly those representing combinations of T between 15 and 30°C and RH > 80 summarized during the 3 weeks after R1.

Temperature and precipitation effects on durum wheat grown in southern Saskatchewan for fifty years

1997 ◽  
Vol 77 (2) ◽  
pp. 215-223 ◽  
Author(s):  
T. N. McCaig
Keyword(s):  
Durum Wheat ◽  
Triticum Turgidum ◽  
Kernel Weight ◽  
Maximum Effect ◽  
Weather Variables ◽  
Kernel Number ◽  
Weather Factors ◽  
Brown Soil ◽  
Soil Zone ◽  
Semi Arid

Approximately 60% of Canadian durum wheat (Triticum turgidum L.) is produced in the semi-arid, Brown soil zone of southern Saskatchewan. The Durum Wheat Cooperative Test (DWCT) provides the means of evaluating potential new cultivars, and has been grown at Swift Current, located near the centre of the Brown soil zone in Saskatchewan, for more than 50 yr. Historical yield-related data from the DWCT were analyzed in conjunction with daily precipitation and maximum daily temperature (MaxDT) data with the objective of improving our understanding of the effects of these weather variables on durum wheat grown in this semi-arid region.The highest correlation between the weather variables and grain yield was during the period near the end of June through early July, approximately the time of anthesis. The correlation with kernel number m−2 (KNum) was maximum near the end of June, while the correlation with kernel weight was highest around the third week of July. The maximum effect of these weather factors in limiting yield in the Brown soil zone was through an impact on KNum around anthesis. Hectolitre weight and time-to-maturi-ty appeared to be influenced mainly by the weather in July, while crop height was determined by the weather near the end of June. An analysis which examined cumulative heat-units above threshold MaxDT of 20, 24, 28 and 32 °C indicated that temperatures >24 °C may be detrimental during early June although high temperatures are less common in June than in July. Yield was also negatively impacted by temperatures >20 °C during the first 3 wk of July.Future yield gains in this semi-arid region may be dependent upon the development of cultivars which are more tolerant of drought and high-temperature stress at anthesis. Key words: Triticum turgidum, kernel number, kernel weight, height, maturity, hectolitre weight

scholarly journals Dispersal Distances for Airborne Spores Based on Deposition Rates and Stochastic Modeling

2007 ◽  
Vol 97 (10) ◽  
pp. 1325-1330 ◽  
Author(s):  
Anders Stockmarr ◽  
Viggo Andreasen ◽  
Hanne Østergård
Keyword(s):  
Fungal Spores ◽  
Two Dimensional ◽  
Airborne Spores ◽  
Modeling Framework ◽  
Deposition Rates ◽  
Spore Release ◽  
Special Cases ◽  
Release Height ◽  
Dispersal Distances ◽  
Parameter Values

A new modeling framework for particle dispersal is explored in the context of the particles being fungal spores dispersed within a field. The model gives rise to both exponentially decreasing and polynomially decreasing two-dimensional densities of deposited fungal spores. We reformulate the model in terms of time to deposition, and show how this concept is equivalent to the deposition rate for fungal spores. Special cases where parameter values for wind and gravitation lead to exponentially or polynomially decreasing densities are discussed, and formulas for one- and two-dimensional densities of deposited spores are given explicitly in terms of parameters for diffusion, wind, gravitation, and spore release height.

scholarly journals Modeling Infection of Strawberry Flowers by Botrytis cinerea Using Field Data

2000 ◽  
Vol 90 (12) ◽  
pp. 1367-1374 ◽  
Author(s):  
Xiangming Xu ◽  
David C. Harris ◽  
Angela M. Berrie
Keyword(s):  
Vapor Pressure ◽  
Botrytis Cinerea ◽  
Vapor Pressure Deficit ◽  
Meteorological Data ◽  
Weather Conditions ◽  
Gray Mold ◽  
Weather Variables ◽  
Infection Models ◽  
The Relationship ◽  
Field Plots

The incidence of strawberry flower infection by Botrytis cinerea was monitored in unsprayed field plots in three successive years together with meteorological data and numbers of conidia in the air. There were large differences in conidia numbers and weather conditions in the 3 years. Three sets of models were derived to relate inoculum and weather conditions to the incidence of flower infection; by inoculum only, by weather variables only, and by both inoculum and weather variables. All the models fitted the observed incidence satisfactorily. High inoculum led to more infection. Models using weather variables only gave more accurate predictions than models using inoculum only. Models using both weather variables and inoculum gave the best predictions, but the improvement over the models based on weather variables only was small. The relationship between incidence of flower infection and inoculum and weather variables was generally consistent between years. Of the weather variables examined, daytime vapor pressure deficit and nighttime temperature had the greatest effect in determining daily incidence of flower infection. Infection was favored by low day vapor pressure deficit and high night temperature. The accuracy and consistency of the weather-based models suggest they could be explored to assist in management of gray mold.

scholarly journals Towards the Prediction of Sandwich Composites Durability in Severe Condition of Temperature: A New Numerical Model Describing the Influence of Material Water Content during a Fire Scenario

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5420
Author(s):  
Juan Pablo Márquez Costa ◽  
Vincent Legrand ◽  
Sylvain Fréour ◽  
Frédéric Jacquemin
Keyword(s):  
High Temperatures ◽  
Sandwich Composite ◽  
Mass Storage ◽  
Severe Condition ◽  
Mechanical Responses ◽  
Advancing Front ◽  
Large Numbers ◽  
Influence Of Water ◽  
Fire Scenarios ◽  
Sandwich Composite Structure

An advanced fire thermal model was developed to predict the evolution of the temperature and decomposition gradient across a sandwich composite structure when exposed to high temperatures (fire). This model allows the prediction of a large numbers of parameters, such as thermal expansion, gas mass storage, porosity, permeability, density, and internal pressure. The highlight of this model is that we consider, in the sandwich constituents (core and skins), additional parameters, such as changing volume porosities, other coupled constituents (as infused resin in the balsa core), and what make the main originality of the present approach: moisture content (free and bounded water). The time dependence of many parameters, i.e., among others, the combustion advancing front and mechanical properties, can be predicted in a large number of material and fire scenarios. The proposed approach was validated in the case of sandwich panels, with glass/polyester or glass/vinyl ester skins and balsa core, exposed to high temperatures up to 750 °C. The influence of water on the thermal and mechanical responses is also highlighted.

Lightning and its association with the frequency of headache in migraineurs: An observational cohort study

Cephalalgia ◽  
2013 ◽  
Vol 33 (6) ◽  
pp. 375-383 ◽  
Author(s):  
Geoffrey V Martin ◽  
Timothy Houle ◽  
Robert Nicholson ◽  
Albert Peterlin ◽  
Vincent T Martin
Keyword(s):  
Electromagnetic Waves ◽  
International Headache Society ◽  
Fungal Spores ◽  
Weather Variables ◽  
Weather Factors ◽  
Lightning Strikes ◽  
Observational Cohort ◽  
Study Population ◽  
Average Current ◽  
The Mean

Aim The aim of this article is to determine if lightning is associated with the frequency of headache in migraineurs. Methods Participants fulfilling diagnostic criteria for International Headache Society-defined migraine were recruited from sites located in Ohio ( n = 23) and Missouri ( n = 67). They recorded headache activity in a daily diary for three to six months. A generalized estimating equations (GEE) logistic regression determined the odds ratio (OR) of headache on lightning days compared to non-lightning days. Other weather factors associated with thunderstorms were also added as covariates to the GEE model to see how they would attenuate the effect of lightning on headache. Results The mean age of the study population was 44 and 91% were female. The OR for headache was 1.31 (95% confidence limits (CL); 1.07, 1.66) during lighting days as compared to non-lightning days. The addition of thunderstorm-associated weather variables as covariates were only able to reduce the OR for headache on lightning days to 1.18 (95% CL; 1.02, 1.37). The probability of having a headache on lightning days was also further increased when the average current of lightning strikes for the day was more negative. Conclusion This study suggests that lightning represents a trigger for headache in migraineurs that cannot be completely explained by other meteorological factors. It is unknown if lightning directly triggers headaches through electromagnetic waves or indirectly through production of bioaerosols (e.g. ozone), induction of fungal spores or other mechanisms. These results should be interpreted cautiously until replicated in a second dataset.

scholarly journals Weather factors in the prediction of western equine encephalitis epidemics in Manitoba

1993 ◽  
Vol 111 (2) ◽  
pp. 373-390 ◽  
Author(s):  
R. F. Sellers ◽  
A. R. Maarouf
Keyword(s):  
Light Trap ◽  
Polar Front ◽  
Encephalitis Virus ◽  
Daily Maximum ◽  
Weather Variables ◽  
Weather Factors ◽  
Equine Encephalitis Virus ◽  
Western Equine Encephalitis Virus ◽  
Maximum Temperatures ◽  
Western Equine Encephalitis

SummaryCases of western equine encephalitis in horses in 1987 in western USA and Manitoba, Canada were examined by backward trajectory analysis of winds. Culex tarsalis mosquitoes infected with western equine encephalitis virus could have been carried on southerly winds from Texas and Oklahoma to northern LTSA and from there to Manitoba. The presence of the Polar front over North Dakota and Minnesota at the end of July would have led to the landing of Cx. tarsalis in Montana and Wisconsin and prevented further carriage into Manitoba. Temperatures in southern Texas during the winter months (average daily maximum temperatures 19.7 °C and higher) would have permitted continuous transmission of western equine encephalitis virus by Cx. tarsalis in this area.Weather factors involved in outbreaks from 1975–88 were analysed to see if epidemics in Manitoba (23 or more cases in horses) could be predicted. The conditions for epidemics could be defined as follows: (a) the number of cases in horses in LTSA was 98 or more, (b) winds were southerly with speeds 45 kmh-1 or higher, and (c) counts of Cx. tarsalis females/light trap per day were 3·2 or higher. There were 3 or fewer cases in Manitoba, when the number of cases in USA was 27 or less, even when Cx. tarsalis counts were higher than 3·2. With Cx. tarsalis counts below 3 and/or unsuitable winds, or the Polar front further south, the number of cases in Manitoba was between 0 and 17, even when the number of cases in USA was from 38–172. Without information on the extent of infection further south, the weather variables would probably be more useful in excluding the possibility of an epidemic in Manitoba than in predicting one.

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