Probability of Disease Occurance for Potato Late Blight in Gorgan (Golestan Province, Iran) Based on Weather Conditions

Document Type : Research Paper

Author

sistant Professor of Research, Agricultural and Natural Resources Research Center of Golestan Province, Gorgan, Iran

Abstract

Late blight, caused by Phytophthora
infestans
, is one of the most important diseases of potato in the world and
Iran, especially in Golestan province. With regard to favorable weather
conditions in the spring, high prevalence of the disease and hence extensive
fungicides application can be observed in potato fields of Gorgan in Ordibehesht
(mid April) of nearly every year. For prediction of the probability of the
disease occurrence, recorded epidemics data in recent 10 years and weather data
of the region were used. In order to modeling, 24 weather variables during six
different periods (all the period of Farvardin (March-April), first 10 days,
second 10 days, third 10 days, first 20 days and last 20 days of the month)
were studied using logistic regression and discriminant analysis methods. After
developing and comparing the statistical models, it was revealed that all the
periods of Farvardin (March-April) is more suitable than other durations for
modeling and four bivariate models were developed using the variables: total
percipitation (P), number of rainy days (R), relative maximum temperature (Tax)
and relative maximum RH (RHax) which showed total correctness value of 80-100%
and coefficient of determination of 99.99%.

Keywords