Paper · 1996 · Journal of Phytopathology

Incorporating an Asymptotic Parameter into the Weibull Model to Describe Plant Disease Progress

C. L. Xiao; K. V. Subbarao; S. M. Zeng

5
claims
8
verbatim quotes
4
citations
2
research areas
—
Not open access

Abstract

Abstract The Weibull model is a flexible growth model that describes both general population growth and plant disease progress. However, lack of an asymptotic parameter has limited its wider application. In the present study, an asymptotic parameter K was introduced into the original Weibull model, written as; y = K {1 − exp [− ( t − a ) c ]}, in which a , b , c and K are location, scale, shape, and asymptotic parameters, respectively, y is the proportion of disease and t is time. A wide range of simulated disease progress data sets were generated using logistic, Gompertz and monomolecular models by specifying different parameter values, and fitted to both original and modified Weibull models. The modified model provided statistically better fits for all data than the original model. The modified model can thus improve the curve‐fitting ability of the original model which often failed to converge, especially when the asymptote is less than 1.0. Actual disease progress data on wheat leaf rust and tomato root rot with different asymptotic values were also used to compare the original and modified Weibull models. The modified model provided a statistically better fit than the original model, and model estimates of asymptotic parameter K were nearly identical to the actual disease maxima reflecting the characteristics of the host‐pathosystem. Comparison of logistic, Gompertz, and Weibull models including parameter K by fitting to the observed data on wheat leaf rust and tomato root rot revealed the applicability of the modified Weibull model, which in a majority of cases provided a statistically superior fit.

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Claims 5

Method / resourceobservedoriginal resultpositivesignificant (as stated)measured

Claim · model-written summary

The modified Weibull model gave statistically better fits than the original model for all simulated disease progress data.

Outcome
statistically better fitse1
Qualifier
for all datae1
Comparator
original modele1

Verbatim

e1

“The modified model provided statistically better fits for all data than the original model”

✓ located verbatim in the source · abstract, characters 703–793 · show in text ↑
Method / resourceobservedoriginal resultpositivesignificant (as stated)measured

Claim · model-written summary

On wheat leaf rust data the modified Weibull model gave a statistically better fit than the original model.

Outcome
statistically better fite5
Comparator
original modele5

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Triticum aestivum
Triticum aestivum · TaxonRasbak · CC BY-SA 3.0 · Wikimedia Commons ↗

Verbatim

e3

“Actual disease progress data on wheat leaf rust and tomato root rot with different asymptotic values were also used to compare the original and modified Weibull models”

✓ located verbatim in the source · abstract, characters 959–1126 · show in text ↑
e5

“The modified model provided a statistically better fit than the original model”

✓ located verbatim in the source · abstract, characters 1128–1206 · show in text ↑
Method / resourceobservedoriginal resultpositivesignificant (as stated)measured

Claim · model-written summary

On tomato root rot data the modified Weibull model gave a statistically better fit than the original model.

Outcome
statistically better fite5
Comparator
original modele5

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Solanum lycopersicum
Solanum lycopersicum · TaxonKod B · CC BY-SA 4.0 · Wikimedia Commons ↗

Verbatim

e3

“Actual disease progress data on wheat leaf rust and tomato root rot with different asymptotic values were also used to compare the original and modified Weibull models”

✓ located verbatim in the source · abstract, characters 959–1126 · show in text ↑
e5

“The modified model provided a statistically better fit than the original model”

✓ located verbatim in the source · abstract, characters 1128–1206 · show in text ↑
Method / resourceobservedoriginal resultpositivemeasured

Claim · model-written summary

Estimates of asymptotic parameter K were nearly identical to the actual disease maxima.

Outcome
estimates of asymptotic parameter Ke2
Qualifier
nearly identicale2
Comparator
actual disease maximae2

Verbatim

e2

“model estimates of asymptotic parameter K were nearly identical to the actual disease maxima”

✓ located verbatim in the source · abstract, characters 1212–1304 · show in text ↑
Method / resourceobservedoriginal resultpositivesignificant (as stated)measured

Claim · model-written summary

The modified Weibull model gave a statistically superior fit in most cases compared with logistic and Gompertz models.

Outcome
statistically superior fite4
Qualifier
in a majority of casese4
Comparator
logistic, Gompertze7

Verbatim

e4

“which in a majority of cases provided a statistically superior fit”

✓ located verbatim in the source · abstract, characters 1565–1631 · show in text ↑
e7

“Comparison of logistic, Gompertz, and Weibull models”

✓ located verbatim in the source · abstract, characters 1361–1413 · show in text ↑