scholarly journals A Decision Support System Based on Degree-Days to Initiate Fungicide Spray Programs for Peach Powdery Mildew in Catalonia, Spain

Plant Disease ◽  
2020 ◽  
Vol 104 (9) ◽  
pp. 2418-2425 ◽  
Author(s):  
Neus Marimon ◽  
Iban Eduardo ◽  
Joaquín Martínez-Minaya ◽  
Antonio Vicent ◽  
Jordi Luque
Keyword(s):  
Powdery Mildew ◽  
Fixed Effects ◽  
Regression Models ◽  
Vapor Pressure Deficit ◽  
Disease Incidence ◽  
Disease Onset ◽  
Environmental Parameters ◽  
Substantial Contribution ◽  
Beta Regression ◽  
Alert Program

The incidence of peach powdery mildew (PPM) on fruit was monitored in commercial peach orchards to i) describe the disease progress in relation to several environmental parameters and ii) establish an operating threshold to initiate a fungicide spray program based on accumulated degree-day (ADD) data. A beta-regression model for disease incidence showed a substantial contribution of the random effects orchard and year, whereas relevant fixed effects corresponded to ADD, wetness duration, and ADD considering vapor pressure deficit and rain. When beta-regression models were fitted for each orchard and year considering only ADD, disease onset was observed at 242 ± 13 ADD and symptoms did not develop further after 484 ± 42 ADD. An operating threshold to initiate fungicide applications was established at 220 ADD, coinciding with a PPM incidence in fruit around 0.05. A validation was further conducted by comparing PPM incidence in i) a standard, calendar-based program, ii) a program with applications initiated at 220 ADD, and iii) a nontreated control. A statistically relevant reduction in disease incidence in fruit was obtained with both fungicide programs, from 0.244 recorded in the control to 0.073 with the 220-ADD alert program, and 0.049 with the standard program. The 220-ADD alert program resulted in 33% reduction in fungicide applications.

scholarly journals Influence of weather parameters on powdery mildew of mango inflorescence in humid tropics of South Gujarat

2021 ◽  
Vol 22 (4) ◽  
pp. 488-493
Author(s):  
J.K. BANA ◽  
JAIPAL S. CHOUDHARY ◽  
P.D. GHOGHARI ◽  
HEMANT SHARMA ◽  
SUSHIL KUMAR ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Powdery Mildew ◽  
Disease Incidence ◽  
Negative Relationship ◽  
Environmental Parameters ◽  
Climatic Conditions ◽  
Humid Tropics ◽  
Efficient Management ◽  
Progress Curve ◽  
Average Relative Humidity

The influence of environmental parameters on the development of powdery mildew caused by Oidium mangiferae Berthet on mango inflorescence was studied for seven consecutive years (2012-18) in humid tropics climatic conditions of South Gujarat. The disease incidence and severity (DIS), area under disease progress curve-AUDPC (A-value) and apparent infection rate (r-value) were recorded at panicle and fruit setting stages of the tree at weekly intervals. The correlation studies showed that incidence and severity of powdery mildew significantly negative relationship with morning relative humidity (r = -0.631; p<0.05 and r = -0.721; p<0.01) and average relative humidity (r = -0.766 and r = -0.787; p<0.01). Temperature (maximum and average) and evaporation showed positive relationship with incidence and severity of powdery mildew. Further, stepwise linear regression model indicated that average relative humidity as single predictor independent variable had the strongest relationship disease incidence and severity, which explained 59 percent disease incidence and 62 percent for disease severity variability. This forewarning model can be useful for efficient management of powdery mildew disease of mango and as well as agro advisory services to farmers.

scholarly journals The Differential Effects of Caregiving Intensity on Overnight Hospitalization in the Previous 2 Years

2020 ◽  
Vol 4 (Supplement_1) ◽  
pp. 76-76
Author(s):  
Kylie Meyer ◽  
Zachary Gassoumis ◽  
Kathleen Wilber
Keyword(s):  
Health Services ◽  
Fixed Effects ◽  
Regression Models ◽  
P Value ◽  
Logistic Regression Models ◽  
Spousal Caregiving ◽  
Health Insurance Status ◽  
Race Ethnicity ◽  
Self Assessed Health ◽  
Retirement Study

Abstract Caregiving for a spouse is considered a major stressor many Americans will encounter during their lifetimes. Although most studies indicate caregiving is associated with experiencing diminished health outcomes, little is known about how this role affects caregivers’ use of acute health services. To understand how spousal caregiving affects the use of acute health services, we use data from the Health and Retirement Study. We apply fixed effects (FE) logistic regression models to examine odds of experiencing an overnight hospitalization in the previous two years according to caregiving status, intensity, and changes in caregiving status and intensity. Models controlled for caregiver gender, age, race, ethnicity, educational attainment, health insurance status, the number of household residents, and self-assessed health. Overall, caregivers were no more likely to experience an overnight hospitalization compared to non-caregivers (OR 0.92; CI 0.84 to 1.00; p-value=0.057). However, effects varied according to the intensity of caregiving and the time spent in this role. Compared to non-caregivers, for example, spouses who provided care to someone with no need for assistance with activities of daily living had lower odds of experiencing a hospitalization (OR 0.77; CI 0.66 to 0.89). In contrast, caregivers who provided care to someone with dementia for 4 to &lt;6 years had 3.29 times the odds of experiencing an overnight hospitalization (CI 1.04 to 10.38; p-value=0.042). Findings indicate that, although caregivers overall appear to use acute health services about as much as non-caregivers, large differences exist between caregivers. Results emphasize the importance of recognizing diversity within caregiving experiences.

scholarly journals Gender-Specific Risk Factors for the Development of Retinal Changes in Children with Type 1 Diabetes

2021 ◽  
Vol 11 (6) ◽  
pp. 588
Author(s):  
Marta Wysocka-Mincewicz ◽  
Joanna Gołębiewska ◽  
Marta Baszyńska-Wilk ◽  
Andrzej Olechowski
Keyword(s):  
Risk Factors ◽  
Type 1 Diabetes ◽  
Uric Acid ◽  
Serum Creatinine ◽  
Regression Models ◽  
Retinal Thickness ◽  
Disease Onset ◽  
Specific Risk ◽  
Gender Specific

The aim of the study was to determine gender-specific risk factor sets which could influence optical coherence tomography (OCT) results in children with type 1 diabetes (T1D). Material and Methods: 175 children with T1D without symptoms of diabetic retinopathy were enrolled, but 330 eyes were used for the final analysis (168 children, mean age 12.81 ± 3.63 years, diabetes duration 4.59 ± 3.71 years). The multivariate regression models for retinal thickness (foveal FT, and parafoveal PFT) and vascular densities (superficial and deep) were carried out separately for both genders using all metabolic and demographic parameters. Results: In the statistically significant multiple regression models for all analyzed OCT parameters for both genders, pH at the onset of diabetes were in existence, as well as for retinal thickness current HbA1c. Duration of continuous insulin infusion (CSII) was an important factor in all parameters, except PFT. For the girls, the most significant factors were daily insulin dose, uric acid, and triglycerides, but for the boys, it was serum creatinine, systolic pressure, and free thyroxine level. Conclusions: We detected significant risk factors set for development of OCT parameters changes, and they were not identical for both genders. Current metabolic control, diabetic ketoacidosis at the disease onset, serum creatinine and longer use of CSII are the most important factors for retinal thickness and vessel densities in both genders in children with type 1 diabetes. For the girls, elements of metabolic syndrome (uric acid and triglycerides) and parameters of insulin amount were more pronounced.

scholarly journals The Epidemiology of Powdery Mildew on Concord Grapes

2001 ◽  
Vol 91 (10) ◽  
pp. 948-955 ◽  
Author(s):  
David M. Gadoury ◽  
Robert C. Seem ◽  
Andrea Ficke ◽  
Wayne F. Wilcox
Keyword(s):  
Powdery Mildew ◽  
Fruit Set ◽  
Disease Incidence ◽  
The United States ◽  
Seasonal Development ◽  
Peak Period ◽  
Late Season ◽  
Stage Of Development ◽  
Concord Grapes ◽  
Moderately Resistant

Vitis labruscana ‘Concord’ is a grape cultivar widely grown in the United States for processing into juice and other grape products. Concord grapes are sporadically but sometimes severely damaged by the grape powdery mildew pathogen, Uncinula necator. Although the foliage is often reported to be moderately resistant to powdery mildew, severe fruit infection occurs in some years. We observed the seasonal development of powdery mildew on leaves, rachises, and berries of unsprayed Concord grapevines. Inoculations of flower and fruit clusters revealed a brief period of berry susceptibility and a protracted period of rachis susceptibility. The rachis remained highly susceptible to infection, and the severity of rachis infection increased throughout the growing season until the rachis formed a periderm shortly before harvest. In contrast, berries were nearly immune to infection within 2 weeks after fruit set. Rachis and berry infections were detected before the disease was observed on foliage, and the incidence of rachis and berry infection often exceeded disease incidence observed on foliage until after fruit acquired substantial ontogenic resistance. Excellent control of fruit infection, and adequate control of leaf infection, was achieved by two fungicide applications targeted at the peak period of fruit susceptibility. Although Concord is thought to be moderately resistant to powdery mildew, the rachis is highly susceptible, and may be the avenue by which prebloom infections make their way onto the developing fruit. Late-season infection of the rachis neither spread to the fruit, nor did it cause fruit to drop prematurely, and may be of little economic consequence on fruit destined for processing. Although fruit of V. vinifera cultivars have been reported to remain susceptible to infection until berry sugar levels reach 8 to 15%, Concord fruit become nearly immune to infection nearly 6 weeks before this stage of development. Because powdery mildew does not become conspicuous on foliage until late summer, it is generally regarded as a late-season problem on Concord grapes, and previous management programs have reflected this belief. However, the greatest contribution to control of fruit infection is due to fungicides applied during the peak period of fruit susceptibility, from bloom until shortly after fruit set, long before the disease is observed on foliage.

scholarly journals Spatial Heterogeneity of the Incidence of Powdery Mildew on Hop Cones

Plant Disease ◽  
2006 ◽  
Vol 90 (11) ◽  
pp. 1433-1440 ◽  
Author(s):  
David H. Gent ◽  
Walter F. Mahaffee ◽  
William W. Turechek
Keyword(s):  
Powdery Mildew ◽  
Spatial Heterogeneity ◽  
Power Law ◽  
Binomial Distribution ◽  
Disease Incidence ◽  
Disease Assessment ◽  
Cluster Sampling ◽  
Data Sets ◽  
Ratio Test ◽  
Frequency Distributions

The spatial heterogeneity of the incidence of hop cones with powdery mildew (Podosphaera macularis) was characterized from transect surveys of 41 commercial hop yards in Oregon and Washington from 2000 to 2005. The proportion of sampled cones with powdery mildew ( p) was recorded for each of 221 transects, where N = 60 sampling units of n = 25 cones assessed in each transect according to a cluster sampling strategy. Disease incidence ranged from 0 to 0.92 among all yards and dates. The binomial and beta-binomial frequency distributions were fit to the N sampling units in a transect using maximum likelihood. The estimation procedure converged for 74% of the data sets where p > 0, and a loglikelihood ratio test indicated that the beta-binomial distribution provided a better fit to the data than the binomial distribution for 46% of the data sets, indicating an aggregated pattern of disease. Similarly, the C(α) test indicated that 54% could be described by the beta-binomial distribution. The heterogeneity parameter of the beta-binomial distribution, θ, a measure of variation among sampling units, ranged from 0.01 to 0.20, with a mean of 0.037 and a median of 0.015. Estimates of the index of dispersion ranged from 0.79 to 7.78, with a mean of 1.81 and a median of 1.37, and were significantly greater than 1 for 54% of the data sets. The binary power law provided an excellent fit to the data, with slope and intercept parameters significantly greater than 1, which indicated that heterogeneity varied systematically with the incidence of infected cones. A covariance analysis indicated that the geographic location (region) of the yards and the type of hop cultivar had little effect on heterogeneity; however, the year of sampling significantly influenced the intercept and slope parameters of the binary power law. Significant spatial autocorrelation was detected in only 11% of the data sets, with estimates of first-order autocorrelation, r1, ranging from -0.30 to 0.70, with a mean of 0.06 and a median of 0.04; however, correlation was detected in only 20 and 16% of the data sets by median and ordinary runs analysis, respectively. Together, these analyses suggest that the incidence of powdery mildew on cones was slightly aggregated among plants, but patterns of aggregation larger than the sampling unit were rare (20% or less of data sets). Knowledge of the heterogeneity of diseased cones was used to construct fixed sampling curves to precisely estimate the incidence of powdery mildew on cones at varying disease intensities. Use of the sampling curves developed in this research should help to improve sampling methods for disease assessment and management decisions.

Understanding Charter School Leaders’ Perceptions of Competition in Arizona

2021 ◽  
pp. 0013161X2110373
Author(s):  
Benjamin Creed ◽  
Huriya Jabbar ◽  
Michael Scott
Keyword(s):  
Logistic Regression ◽  
School Choice ◽  
Charter School ◽  
Fixed Effects ◽  
Regression Models ◽  
School Leaders ◽  
State Level ◽  
Local Market ◽  
School Practices ◽  
Logistic Regression Models

Purpose: School choice policies are expected to generate competition leading to improvement in school practices. However, little is known about how competition operates in public education—particularly in charter schools. This paper examines charter-school leaders’ competitive perception formation and the actions taken in response to competition. Research Methods: Using Arizona charter-school leaders’ responses to an original survey, Arizona Department of Education data, and the Common Core of Data, we examined the factors predicting the labeling of a school as a competitor. We estimated fixed effects logistic regression models which examine factors predicting the labeling of competitor schools and of top competitors. We used logistic regression models to understand charter-school leaders’ responses to competition. Findings: We find charter-school leaders in Arizona perceived at least some competition with other schools, and their perceptions vary by urbanicity. While distance between schools mattered generally for labeling a school as a competitor, distance did not factor into labeling “top competitor” schools. Student outcomes did not predict competition between schools, but student demographics were associated with labeling a school a competitor. Charter-school leaders responded to competition through changes in outreach and advertising rather than curriculum and instruction. Competitive responses were related to the respondent school’s quality and the level of perceived competition. Implications for Research and Practice: We found charter-school leaders perceive competition and respond by changing school practices. Responses typically focus on marketing activities over productive responses. The novel state-level analysis allows us to test the effects of local market conditions typically absent in the literature.

A reflexion on the environmental effect on the transmission of COVID-19

2021 ◽  
Author(s):  
Victor L Barradas ◽  
Monica Ballinas
Keyword(s):  
Solar Radiation ◽  
Air Temperature ◽  
Low Temperatures ◽  
Minimum Distance ◽  
Vapor Pressure Deficit ◽  
Environmental Parameters ◽  
Air Humidity ◽  
Evaporative Demand ◽  
Small Water ◽  
The Hours

&lt;p&gt;This research is a general reflection of the possible transmission not only of COVID-19 but of any influenza disease depending on environmental parameters such as solar radiation, air humidity and air temperature (vapor pressure deficit), evoking the Penman-Monteith model regarding the evaporation of the water that constitutes the small water droplets (aerosols) that carry the virus. In this case the evapotranspiration demand of the atmosphere with which it can be deduced that the spread of the disease will be higher in those places with less evaporative demand, that is, high air humidity and / or low temperatures, and / or low radiation intensities, and vice versa. It can also be deduced that the hours of greatest potential contagion are the night hours, while those with the lowest risk are between 2:00 p.m. and 4:00 p.m. On the other hand, in those rooms with low temperatures the contagion would be more effective. So, considering that the drops produced by a sneeze, by speaking or breathing can go beyond two meters away, it is roughly explained that the use of face masks and keeping a safe minimum distance of two meters can limit transmission of viruses and / or infections. However, this practice is not entirely safe as the environment can play an important role. What is recommended to reduce the spread of these pathogens is to produce high evaporative demands: increasing solar radiation, and increasing air temperature and reducing air humidity, which is practice that can be effective in closed rooms.&lt;/p&gt;

scholarly journals Sequential Sampling for Estimation and Classification of the Incidence of Hop Powdery Mildew II: Cone Sampling

Plant Disease ◽  
2007 ◽  
Vol 91 (8) ◽  
pp. 1013-1020 ◽  
Author(s):  
David H. Gent ◽  
William W. Turechek ◽  
Walter F. Mahaffee
Keyword(s):  
Powdery Mildew ◽  
Binomial Distribution ◽  
Disease Incidence ◽  
Sequential Sampling ◽  
Model Construction ◽  
Data Sets ◽  
Data Set ◽  
Sampling Plans ◽  
Simulated Sampling

Sequential sampling models for estimation and classification of the incidence of powdery mildew (caused by Podosphaera macularis) on hop (Humulus lupulus) cones were developed using parameter estimates of the binary power law derived from the analysis of 221 transect data sets (model construction data set) collected from 41 hop yards sampled in Oregon and Washington from 2000 to 2005. Stop lines, models that determine when sufficient information has been collected to estimate mean disease incidence and stop sampling, for sequential estimation were validated by bootstrap simulation using a subset of 21 model construction data sets and simulated sampling of an additional 13 model construction data sets. Achieved coefficient of variation (C) approached the prespecified C as the estimated disease incidence, [Formula: see text], increased, although achieving a C of 0.1 was not possible for data sets in which [Formula: see text] < 0.03 with the number of sampling units evaluated in this study. The 95% confidence interval of the median difference between [Formula: see text] of each yard (achieved by sequential sampling) and the true p of the original data set included 0 for all 21 data sets evaluated at levels of C of 0.1 and 0.2. For sequential classification, operating characteristic (OC) and average sample number (ASN) curves of the sequential sampling plans obtained by bootstrap analysis and simulated sampling were similar to the OC and ASN values determined by Monte Carlo simulation. Correct decisions of whether disease incidence was above or below prespecified thresholds (pt) were made for 84.6 or 100% of the data sets during simulated sampling when stop lines were determined assuming a binomial or beta-binomial distribution of disease incidence, respectively. However, the higher proportion of correct decisions obtained by assuming a beta-binomial distribution of disease incidence required, on average, sampling 3.9 more plants per sampling round to classify disease incidence compared with the binomial distribution. Use of these sequential sampling plans may aid growers in deciding the order in which to harvest hop yards to minimize the risk of a condition called “cone early maturity” caused by late-season infection of cones by P. macularis. Also, sequential sampling could aid in research efforts, such as efficacy trials, where many hop cones are assessed to determine disease incidence.

scholarly journals Asymmetric Fixed Effects Models for Panel Data

2018 ◽  
Author(s):  
Paul D Allison
Keyword(s):  
Logistic Regression ◽  
Panel Data ◽  
Opposite Direction ◽  
Difference Method ◽  
Fixed Effects ◽  
Regression Models ◽  
Social Phenomena ◽  
Logistic Regression Models ◽  
Fixed Effects Models ◽  
The Difference

Standard fixed effects methods presume that effects of variables are symmetric: the effect of increasing a variable is the same as the effect of decreasing that variable but in the opposite direction. This is implausible for many social phenomena. York and Light (2017) showed how to estimate asymmetric models by estimating first-difference regressions in which the difference scores for the predictors are decomposed into positive and negative changes. In this paper, I show that there are several aspects of their method that need improvement. I also develop a data generating model that justifies the first-difference method but can be applied in more general settings. In particular, it can be used to construct asymmetric logistic regression models.

scholarly journals Effective Management of Cucumber Powdery Mildew with Essential Oils

Agriculture ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1177
Author(s):  
Yasser S. Mostafa ◽  
Mohamed Hashem ◽  
Ali M. Alshehri ◽  
Saad Alamri ◽  
Ebrahem M. Eid ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Essential Oils ◽  
Disease Incidence ◽  
Its Region ◽  
Dry Weight ◽  
Positive Control ◽  
Powdery Mildew Fungus ◽  
Membrane Injury ◽  
Cucumber Powdery Mildew

This research evaluated the efficacy of essential oils in the management of cucumber powdery mildew. Essential oils of lemongrass, lemon, thyme, peppermint, abundance blend, purification blend, and thieves blend were tested in vitro and under greenhouse conditions in two separate experiments. The effects of essential oils were tested against powdery mildew disease at concentrations of 1.0–2.5 mL/L, and the consequent impact of the oils on plant growth was evaluated. Powdery mildew fungus, Podosphaera xanthii, was identified using sequencing of the ITS region. The essential oils significantly reduced disease incidence up to 77.3% compared with the positive control (p < 0.5). Moreover, the essential oils increased the plant length (up to 187 cm), leaf area (up to 27.5 cm2), fresh weight (up to 123 g), dry weight (up to 22.5 g), number of flowers (16.3), and metabolite content compared with the positive control (p < 0.5). Cell membrane injury decreased significantly in the oil-treated pants (p < 0.5), indicating the protective effect of essential oils. This study recommends the application of essential oils in an appropriate dose (2.5 mL/L) to protect cucumber plants against powdery mildew. Overdose of the oils (more than 2.5 mL/L) should be avoided due to adverse effects.

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