Development of a weather-based forecasting model for Alternaria leaf blight of carrot

ABSTRACT In the present study, under controlled conditions, the influence of temperature (10, 15, 20, 25 and 30°C) and leaf wetness duration (6, 12, 24 and 48 hours) was studied on the severity of Alternaria leaf blight of carrot caused by Alternaria dauci. The relative density of lesions was influenced by temperature and leaf wetness duration (P<0.05). The disease was more severe at the temperature of 25°C. Data underwent non-linear regression analysis. The generalized beta function was used for fitting the data on disease severity and temperature, while a logistic function was chosen to represent the effect of leaf wetness duration on the severity of leaf blight. The response surface resulting of the product of the two functions was expressed as ES = 0.004993 * (((x-8)1.13125) * ((36-x)0.53212)) * (0.39219/(1+25.93072 * exp (-0.16704*y))), where: ES represents the estimated severity value (0.1); x, temperature (ºC) and y, leaf wetness duration (hours). This model must be validated under field conditions to be used as a forecasting model for Alternaria leaf blight of carrot.

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Influence of temperature and daily leaf wetness duration on the severity of bacterial leaf blight of garlic

Summa Phytopathologica ◽

10.1590/0100-5405/214149 ◽

2021 ◽

Vol 47 (3) ◽

pp. 180-182

Author(s):

Leandro Luiz Marcuzzo ◽

Débora Füchter

Keyword(s):

Bacterial Blight ◽

Linear Regression Analysis ◽

Beta Function ◽

Logistic Function ◽

Leaf Blight ◽

Bacterial Leaf Blight ◽

Leaf Wetness ◽

Climate Control ◽

Leaf Wetness Duration ◽

Influence Of Temperature

ABSTRACT In the present study, climate control chamber conditions were adopted to investigate the influence of temperature (10, 15, 20, 25 and 30°C) and leaf wetness duration (6, 12, 24 and 48 hours) on the severity of bacterial leaf blight of garlic, caused by Pseudomonas marginalis pv. marginalis. The relative density of lesions was influenced by temperature and leaf wetness duration (P<0.05). The disease was more severe at 20°C. The obtained data underwent non-linear regression analysis. Generalized beta function was used to fit the data on severity and temperature, while a logistic function was chosen to represent the effect of leaf wetness duration on the severity of bacterial blight. The response surface resulting of the product of those two functions was expressed as ES = 0.019419 * (((x-5)0.5893) * ((35-x)0.5474)) * (0.51754/(1+23.59597* exp (-0.145695*y))), where: ES represents the estimated severity value (0.1); x, the temperature (ºC), and y, the daily leaf wetness duration (hours). This model shall be validated under field conditions to assess its use as a forecast system for bacterial leaf blight of garlic.

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Development of a weather-based model for Botrytis leaf blight of onion

Summa Phytopathologica ◽

10.1590/0100-5405/2034 ◽

2016 ◽

Vol 42 (1) ◽

pp. 92-93 ◽

Cited By ~ 6

Author(s):

Leandro Luiz Marcuzzo ◽

Roberto Haveroth

Keyword(s):

Climate Model ◽

Logistic Function ◽

Temperature Data ◽

Leaf Blight ◽

Leaf Wetness ◽

Generalized Function ◽

Nonlinear Regression Analysis ◽

Computational System ◽

Leaf Wetness Duration ◽

Influence Of Temperature

ABSTRACT In the present study, onion plants were tested under controlled conditions for the development of a climate model based on the influence of temperature (10, 15, 20 and 25°C) and leaf wetness duration (6, 12, 24 and 48 hours) on the severity of Botrytis leaf blight of onion caused by Botrytis squamosa. The relative lesion density was influenced by temperature and leaf wetness duration (P <0.05). The disease was most severe at 20°C. Data were subjected to nonlinear regression analysis. Beta generalized function was used to adjust severity and temperature data, while a logistic function was chosen to represent the effect of leaf wetness on the severity of Botrytis leaf blight. The response surface obtained by the product of two functions was expressed as ES = 0.008192 * (((x-5)1.01089) * ((30-x)1.19052)) * (0.33859/(1+3.77989 * exp (-0.10923*y))), where ES represents the estimated severity value (0.1); x, the temperature (°C); and y, the leaf wetness (in hours). This climate model should be validated under field conditions to verify its use as a computational system for the forecasting of Botrytis leaf blight in onion.

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Influence of temperature and leaf wetness duration in the severity of Cercospora leaf spot of beet

Summa Phytopathologica ◽

10.1590/0100-5405/2111 ◽

2016 ◽

Vol 42 (1) ◽

pp. 89-91

Author(s):

Leandro Luiz Marcuzzo ◽

Roberto Haveroth ◽

Aline Nacimento

Keyword(s):

Leaf Spot ◽

Beta Function ◽

Logistic Function ◽

Leaf Wetness ◽

Forecast System ◽

Cercospora Leaf Spot ◽

Leaf Wetness Duration ◽

Influence Of Temperature ◽

Wetness Period ◽

Leaf Wetness Period

ABSTRACT In the present study, the influence of temperature (15, 20, 25, 30 and 35°C) and leaf wetness period (6, 12, 24 and 48 hours) on the severity of Cercospora leaf spot of beet, caused by Cercospora beticola, was studied under controlled conditions. Lesion density was influenced by temperature and leaf wetness duration (P<0.05). Data were subjected to nonlinear regression analysis. The generalized beta function was used for fitting the disease severity and temperature data, while a logistic function was chosen to represent the effect of leaf wetness on the severity of Cercospora leaf spot. The response surface resultant of the product of the two functions was expressed as ES = 0.0001105 * (((x-8)2.294387) * ((36-x)0.955017)) * (0.39219/(1+25.93072 * exp (-0.16704*y))), where: ES represents the estimated severity value (0.1); x, the temperature (ºC) and y, the leaf wetness duration (hours). This model should be validated under field conditions to assess its use as a computational forecast system for Cercospora leaf spot of beet.

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A Model Based on Temperature and Leaf Wetness Duration for Establishment of Alternaria Leaf Blight of Muskmelon

Phytopathology ◽

10.1094/phyto-82-890 ◽

1992 ◽

Vol 82 (8) ◽

pp. 890 ◽

Cited By ~ 35

Author(s):

K. J. Evans

Keyword(s):

Leaf Blight ◽

Leaf Wetness ◽

Leaf Wetness Duration ◽

Model Based ◽

Alternaria Leaf Blight

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The Role of Ascospores and Conidia, in Relation to Weather Variables, in the Epidemiology of Stemphylium Leaf Blight of Onion

Plant Disease ◽

10.1094/pdis-06-20-1283-re ◽

2020 ◽

Author(s):

Bruce Gossen ◽

Cyril Selasi Tayviah ◽

Mary Ruth McDonald

Keyword(s):

Disease Risk ◽

Meteorological Data ◽

Growing Season ◽

Early Spring ◽

Leaf Blight ◽

Forecasting Model ◽

Leaf Wetness ◽

Disease Forecasting ◽

Leaf Wetness Duration ◽

Air Temperatures

Stemphylium leaf blight (SLB), caused by Stemphylium vesicarium, is an important foliar disease of onion in northeastern North America. The pathogen produces conidia and ascospores, but the relative contributions of these spore types to epidemics in onion is not known. An effective disease forecasting model is needed to predict disease risk and to time fungicide applications. Determining the abundance of ascospores and conidia during the growing season couldwill contribute to a disease forecasting model. Air-borne ascospores and conidia of S. vesicarium were trapped during the growing season of 2015 and 2016 at an onion trial site in southern Ontario, Canada, using a Burkard 7-day volumetric sampler. Meteorological data wereas recorded hourly. Ascospore numbers peaked before the crop was planted and declined rapidly with time and at daily mean air temperatures > 15 °C. Conidia were present throughout the growing season and appear to be closely related to the development of SLB on onion. Daily spore concentrations were variable, but 59 to 73% of ascospores and ~60% of conidia were captured between 0600 to1200 h. Spore concentrations increased 24 to 72 h after rainfall and . Other variables associated with moisture, such as precipitation and leaf wetness duration, were consistently and positively associated with increases in numbers of conidia and subsequent SLB incidence . The first symptoms of SLB coincided with high numbers of conidia, rainfall, leaf wetness duration ≥ 8 h and days with average daily temp ≥ 18°C oC. The number of air-borne ascospores was very low by the time SLB symptoms were observed. Ascospores may initiate infection on alternative hosts in early spring, while conidia are the most important inoculum or the epidemic on onions.

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Influence of Temperature and Leaf Wetness Duration on Infection of Strawberry Leaves by Mycosphaerella fragariae

Phytopathology ◽

10.1094/phyto.2000.90.10.1120 ◽

2000 ◽

Vol 90 (10) ◽

pp. 1120-1125 ◽

Cited By ~ 32

Author(s):

O. Carisse ◽

G. Bourgeois ◽

J. A. Duthie

Keyword(s):

Leaf Surface ◽

Leaf Wetness ◽

Infection Model ◽

Controlled Environment ◽

Conidial Suspension ◽

Precise Description ◽

Leaf Wetness Duration ◽

Influence Of Temperature ◽

Mycosphaerella Fragariae ◽

Weibull Equation

In controlled environment studies, the influence of temperature and wetness duration on infection of strawberry leaves by Mycosphaerella fragariae was quantified by inoculating plants with a conidial suspension and incubating them at various combinations of temperature (5 to 35°C) and leaf wetness duration (0 to 96 h). Infection was expressed as the number of lesions per square centimeter of leaf surface and relative infection was used to develop an infection model. Younger leaves were more susceptible to infection. Regardless of temperature and duration of leaf wetness, only few lesions developed on the oldest (19 to 21 days old) and intermediate leaves (12 to 15 days old), respectively (maximum of 1.7 and 2.3 lesions per cm2) as compared to the youngest leaves (5 to 7 days old; maximum of 12.6 lesions per cm2). On the youngest leaves, lesions developed at all temperatures except at 35°C, and the number of lesions, for all leaf wetness durations, increased gradually from 5 to 25°C and decreased sharply from 25 to 30°C. For temperatures of 15 and 20°C, the number of lesions increased gradually when leaf wetness duration increased from 12 to 96 h. At 25°C, the number of lesions increased with increasing leaf wetness from 12 to 48 h and then at a higher rate from 48 to 96 h. The optimal temperature for infection was 25°C. For most temperatures, a minimum of 12 h of leaf wetness was necessary for infection (more than 1 lesion per cm2). Relative infection was modeled as a function of both temperature and wetness duration using a modified version of the Weibull equation (R 2 = 0.98). The resulting equations provided a precise description of the response of M. fragariae to temperature. The model was sufficiently flexible to account for most characteristics of the response of M. fragariae to wetness duration. The model was used to construct a risk chart that can be used to estimate the potential risk for infection based on observed or forecasted temperature and leaf wetness duration.

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