scholarly journals Spatial variability of leaf wetness duration in a 'Niagara Rosada' vineyard

2008 ◽  
Vol 28 (1) ◽  
pp. 104-114
Author(s):  
Jorge Lulu ◽  
Paulo C. Sentelhas ◽  
Mário J. Pedro Júnior ◽  
José R. M. Pezzopane ◽  
Gabriel C. Blain
Keyword(s):  
Spatial Variability ◽  
Leaf Wetness ◽  
Crop Canopy ◽  
Vitis Labrusca ◽  
Leaf Wetness Duration ◽  
Canopy Position ◽  
Significant Difference ◽  
The Relationship ◽  
Electronic Sensors ◽  
Niagara Rosada

Despite considerable efforts to develop accurate electronic sensors to measure leaf wetness duration (LWD), little attention has been given to studies about how is LWD variability in different positions of the crop canopy. In order to evaluate the influence of 'Niagara Rosada' (Vitis labrusca) grapevine structure on the spatial variability of LWD, the objective of this study was to determine the canopy position of the ‘Niagara RosadaÂ’ table grape with longer LWD and its correlation with measured standard LWD over turfgrass. LWD was measured in four different canopy positions of the vineyard (sensors deployed at 45º with the horizontal): at the top of the plants, with sensors facing southwest and northeast (Top-SW and Top-NE), and at the grape bunches height, with sensors facing southwest and northeast (Bottom-SW and Bottom-NE). No significant difference was observed between the top (1.6 m) and the bottom (1.0 m) of the canopy and also between the southwest and northeast face of the plants. The relationship between standard LWD over turfgrass and crop LWD in different positions of the grape canopy showed a define correlation, with R² ranging from 0.86 to 0.89 for all period, from 0.72 to 0.77 for days without rain, and from 0.89 to 0.91 for days with rain.

scholarly journals Estimating leaf wetness duration over turfgrass, and in a 'Niagara Rosada' vineyard, in a subtropical environment

2008 ◽  
Vol 65 (spe) ◽  
pp. 10-17 ◽  
Author(s):  
Jorge Lulu ◽  
Paulo Cesar Sentelhas ◽  
Mário José Pedro Júnior ◽  
José Ricardo Macedo Pezzopane ◽  
Gabriel Constantino Blain
Keyword(s):  
High Accuracy ◽  
Training System ◽  
Dew Point ◽  
Classification And Regression Tree ◽  
Leaf Wetness ◽  
Good Precision ◽  
Weather Station ◽  
Leaf Wetness Duration ◽  
Confidence Index ◽  
Niagara Rosada

Leaf wetness duration (LWD) is a key parameter in agrometeorology because it is related to plant disease occurrence. As LWD is seldomly measured in a standard weather station it must be estimated to run warning systems for schedule chemical disease control. The objective of the present study was to estimate LWD over turfgrass considering different models with data from a standard weather station, and to evaluate the correlation between estimated LWD over turfgrass and LWD measured in a 'Niagara Rosada' vineyard, cultivated in a hedgerow training system, in Jundiaí, São Paulo State, Brazil. The wetness sensors inside the vineyard were located at the top of the plants, deployed at an inclination angle of 45º and oriented southwest, with three replications. The methods used to estimate LWD were: number of hours with relative humidity above 90% (NHRH > 90%), dew point depression (DPD), classification and regression tree (CART) and Penman-Monteith (PM). The CART model had the best performance to estimate LWD over turfgrass, with a good precision (R² = 0.82) and a high accuracy (d = 0.94), resulting in a good confidence index (c = 0.85). The results from this model also presented a good correlation with measured LWD inside the vineyard, with a good precision (R² = 0.87) and a high accuracy (d = 0.96), resulting in a high confidence index (c = 0.93), showing that LWD in a 'Niagara Rosada' vineyard can be estimated with data from a standard weather station.

scholarly journals Influence of Leaf Wetness Duration and Temperature on Infection of Grape Leaves by Elsinoë ampelina under Controlled and Vineyard Conditions

Plant Disease ◽  
2020 ◽  
Vol 104 (11) ◽  
pp. 2817-2822
Author(s):  
Odile Carisse ◽  
Audrey Levasseur ◽  
Caroline Provost
Keyword(s):  
Leaf Area ◽  
Weather Conditions ◽  
Leaf Wetness ◽  
Predictive Capacity ◽  
Leaf Wetness Duration ◽  
Infection Period ◽  
Richards Model ◽  
Elsinoe Ampelina ◽  
Independent Observations ◽  
The Relationship

On susceptible varieties, indirect damage to vines infected by Elsinoë ampelina range from reduced vigor to complete defoliation while, on berries, damage ranges from reduced quality to complete yield loss. Limited knowledge about the relationship between weather conditions and infection makes anthracnose management difficult and favors routine application of fungicides. The influence of leaf wetness duration and temperature on infection of grape leaves by E. ampelina was studied under both controlled and vineyard conditions. For the controlled conditions experiments, the five youngest leaves of potted vines (Vidal) were inoculated with a conidia suspension and exposed to combinations of six leaf wetness durations (from 0 to 24 h) and six constant temperatures (from 5 to 30°C). A week after each preset infection period, the percent leaf area diseased (PLAD) was assessed. At 5°C, regardless of the leaf wetness duration, no disease developed. At 10 and at 15 to 30°C, the minimum leaf wetness durations were 4 and 6 h, respectively. Above the minimum wetness duration, at temperatures from 10 to 30°C, PLAD increased linearly, with increasing leaf wetness up to 12 h, and then at a lower rate from 12 to 24 h. The optimal temperature for infection was 25°C. Relative infection was modeled as a function of both temperature and wetness duration using a Richards model (R2 = 0.93). The predictive capacity of the model was evaluated with data collected in experimental vineyard plots exposed to natural wetness durations or artificial wetness durations created using sprinklers. In total, 264 vineyard infection events were used to validate the controlled experiments model. There was a linear relationship between the risk of infection estimated with the model and the observed severity of anthracnose (R2 = 90); however, the model underestimated disease severity. A risk chart was constructed using the model corrected for vineyard observations and three levels of risk, with light, moderate, and severe risks corresponding to ≤5, >5% to ≤25, and >25% leaf area diseased, respectively. Overall, 93.9% of 132 independent observations were correctly classified, with 100, 29.4, and 9.4% of the light, moderate, and severe risks, respectively.

scholarly journals Spatial variability of leaf wetness duration in cotton, coffee and banana crop canopies

2008 ◽  
Vol 65 (spe) ◽  
pp. 18-25 ◽  
Author(s):  
Eduardo Alvarez Santos ◽  
Paulo Cesar Sentelhas ◽  
José Eduardo Macedo Pezzopane ◽  
Luiz Roberto Angelocci ◽  
José Eduardo Boffino Almeida Monteiro
Keyword(s):  
Spatial Variability ◽  
Plant Disease ◽  
Leaf Wetness ◽  
Weather Station ◽  
Cotton Crop ◽  
Leaf Wetness Duration ◽  
Disease Epidemiology ◽  
Plant Disease Management ◽  
Upper Third ◽  
Banana Crop

Despite the importance of leaf wetness duration for plant disease epidemiology, there has been little attention paid to research on how its variability relates to different cropping situations. The objective of this study was to evaluate the spatial variability of leaf wetness duration (LWD) in three crops, comparing these measurements with turfgrass LWD, obtained in a standard weather station. LWD was measured by electronic sensors in three crops with different canopy structures and leaf area: cotton, coffee and banana. For the cotton crop, cylindrical sensors were deployed at the lower third and on the top of the canopy, facing southwest. For the coffee crop, flat plate sensors were installed in the lower third of the canopy facing northeast and southwest; in the middle third facing northeast and southwest; and inside and on the top of the canopy. For the banana canopy, cylindrical sensors were used to measure LWD in the lower third of the canopy and in the upper third of the plant. Turfgrass LWD was simultaneously measured in a nearby standard weather station. The LWD showed different patterns of variation in the three crop canopies. For coffee plants, the longest LWD was found in the lower portions of the canopy; for the banana crop, the upper third of the canopy showed the longest LWD; whereas for the cotton crop no difference was observed between the top and lower third of the canopy. Turfgrass LWD presented a good relationship with LWD measured on the top or in the upper third of the crops. Thus, the estimate of crop LWD can be perfomed based on turfgrass LWD, this being a useful tool for plant disease management purposes for crops in which the longer LWD occurs at the upper canopy portion.

Spatial variability of leaf wetness duration in different crop canopies

2005 ◽  
Vol 49 (6) ◽  
pp. 363-370 ◽  
Author(s):  
Paulo C. Sentelhas ◽  
Terry J. Gillespie ◽  
Jean C. Batzer ◽  
Mark L. Gleason ◽  
José Eduardo B. A. Monteiro ◽  
...  
Keyword(s):  
Spatial Variability ◽  
Leaf Wetness ◽  
Leaf Wetness Duration

Evaluation of a Penman–Monteith approach to provide “reference” and crop canopy leaf wetness duration estimates

2006 ◽  
Vol 141 (2-4) ◽  
pp. 105-117 ◽  
Author(s):  
Paulo C. Sentelhas ◽  
Terry J. Gillespie ◽  
Mark L. Gleason ◽  
José Eduardo B.M. Monteiro ◽  
José Ricardo M. Pezzopane ◽  
...  
Keyword(s):  
Leaf Wetness ◽  
Crop Canopy ◽  
Leaf Wetness Duration

Modeling temporal and spatial variability of leaf wetness duration in Brazil

2014 ◽  
Vol 120 (3-4) ◽  
pp. 455-467 ◽  
Author(s):  
Clayton Alcarde Alvares ◽  
Eduardo Moré de Mattos ◽  
Paulo Cesar Sentelhas ◽  
Aline Cristina Miranda ◽  
José Luiz Stape
Keyword(s):  
Spatial Variability ◽  
Leaf Wetness ◽  
Leaf Wetness Duration ◽  
Temporal And Spatial Variability ◽  
Temporal And Spatial

Effects of temperature and leaf wetness duration on infection of pear leaves by Venturia pirina

2000 ◽  
Vol 51 (1) ◽  
pp. 97 ◽  
Author(s):  
O. N. Villalta ◽  
W. S. Washington ◽  
G. M. Rimmington ◽  
P. A. Taylor
Keyword(s):  
Disease Severity ◽  
Field Experiments ◽  
Leaf Wetness ◽  
Leaf Wetness Duration ◽  
Controlled Conditions ◽  
Pyrus Communis L ◽  
Venturia Pirina ◽  
Effects Of Temperature ◽  
Relationship Of ◽  
The Relationship

The effects of temperature and wetness duration on the infection of pear leaves (Pyrus communis L.) by Venturia pirina were studied by inoculating plants with ascospores and conidia under controlled conditions and in the field. Under controlled inoculations, minimum wetness durations that lead to leaf infections by ascospores were 27, 15, 13, 11, 10, 9, and 9 h at 4, 8, 10, 12, 15, 20, and 25°C, respectively. In parallel inoculations with conidia, the minimum wetness durations that lead to leaf infections were similar to ascospores at temperatures between 12°C and 25°C, but at lower temperatures (4, 8, 10°C), conidia infected leaves only after an additional 2 h of leaf wetness. The relationship between minimum wetness times and temperature was best described using an exponential regression. In field experiments, leaf infection on plants inoculated with ascospores and conidia under various naturally occurring wetness and temperature conditions was in close agreement with those under controlled conditions. Disease severity (percent of leaf area infected) increased with increasing leaf wetness duration at all temperatures. The optimum temperature for infection was 20°C. Analysis of variance with orthogonal polynomial contrasts was used to define the relationship of the angular transformation of disease severity to temperature and leaf wetness duration.

scholarly journals A Model Defining the Relationship Between Temperature and Leaf Wetness Duration, and Infection of Watermelon by Colletotrichum orbiculare

Plant Disease ◽  
1997 ◽  
Vol 81 (7) ◽  
pp. 739-742 ◽  
Author(s):  
J. S. Monroe ◽  
J. B. Santini ◽  
R. Latin
Keyword(s):  
Experimental Design ◽  
Orthogonal Polynomial ◽  
Analysis Of Variance ◽  
Leaf Wetness ◽  
Controlled Environment ◽  
Optimum Temperature ◽  
Colletotrichum Orbiculare ◽  
Leaf Wetness Duration ◽  
Relationship Of ◽  
The Relationship

Controlled environment experiments were conducted to determine the relationship between temperature, leaf wetness duration, and infection of watermelon by Colletotrichum orbiculare. Flats of watermelon seedlings were inoculated and exposed to various combinations of temperature (12, 15, 18, 21, 24, 27, and 30°C) and leaf wetness duration (2, 4, 8, 12, 16, and 24 h). The experimental design was a split-plot, with whole units represented by temperature and subunits represented by leaf wetness duration. Anthracnose incidence, defined as the percentage of symptomatic seedlings in each flat 10 days after inoculation, increased with increasing leaf wetness duration at all levels of temperature. The optimum temperature for infection ranged from 21 to 24°C. At most temperatures, as little as 2 h of leaf wetness was required for infection. Analysis of variance with orthogonal polynomial contrasts and multiple regression procedures was used to define the relationship of anthracnose incidence to temperature and leaf wetness duration.

Relationship between Thyroglobulin and Tumor Detectabilily with Thallium-201 in Differentiated Thyroid Cancer

2000 ◽  
Vol 39 (01) ◽  
pp. 10-15 ◽  
Author(s):  
S. P. Müller ◽  
Ch. Reiners ◽  
A. Bockisch ◽  
Katja Brandt-Mainz
Keyword(s):  
Thyroid Cancer ◽  
Differentiated Thyroid Cancer ◽  
Roc Analysis ◽  
Tsh Suppression ◽  
Significant Difference ◽  
Test Specificity ◽  
The Relationship ◽  
Tumor Scintigraphy ◽  
Tsh Stimulation

Summary Aim: Tumor scintigraphy with 201-TICI is an established diagnostic method in the follow-up of differentiated thyroid cancer. We investigated the relationship between thyroglobulin (Tg) level and tumor detectability. Subject and methods: We analyzed the scans of 122 patients (66 patients with proven tumor). The patient population was divided into groups with Tg above (N = 33) and below (N = 33) 5 ng/ml under TSH suppression or above (N = 33) and below (N = 33) 50 ng/ml under TSH stimulation. Tumor detectability was compared by ROC-analysis (True-Positive-Fraction test, specificity 90%). Results: There was no significant difference (sensitivity 75% versus 64%; p = 0.55) for patients above and below 5 ng/ml under TSH suppression and a just significant difference (sensitivity 80% versus 58%; p = 0.04) for patients above and below 50 ng/ml under TSH stimulation. In 18 patients from our sample with tumor, Tg under TSH suppression was negative, but 201-TICI-scan was able to detect tumor in 12 patients. Conclusion: Our results demonstrate only a moderate dependence of tumor detectability on Tg level, probably without significant clinical relevance. Even in patients with slight Tg elevation 201-TICI scintigraphy is justified.

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