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The effects of constant and fluctuating temperatures on the length of the incubation period of apple powdery mildew ( Podosphaera leucotricha )
Author(s) -
XU XM.
Publication year - 1996
Publication title -
plant pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.928
H-Index - 85
eISSN - 1365-3059
pISSN - 0032-0862
DOI - 10.1111/j.1365-3059.1996.tb02903.x
Subject(s) - powdery mildew , mildew , biology , incubation , incubation period , relative humidity , constant (computer programming) , horticulture , botany , zoology , thermodynamics , physics , biochemistry , computer science , programming language
The effects of constant and fluctuating temperatures on the incubation period of apple powdery mildew, caused by Podosphaera leucotricha , were studied. At constant temperatures, incubation periods ranged from 3 to 12 days over temperatures 8°C–30°C, and no visible lesions developed at 32°C. A nonlinear model was developed to describe the relationship between temperature and the rate of mildew colony development. The resulting curve is bell‐shaped with an optimum temperature at about 23°C. When this model was used to predict mildew development under fluctuating temperatures at an integration step of 48 min, however, it consistently overestimated development rate for fluctuating periods with average temperatures higher than 20°C. A nonlinear model was also fitted directly to the fluctuating temperature data, thus taking into account the nonlinear effect. The overestimation of development rate by the constant model for high temperatures was confirmed when the two models were compared. This overestimation probably resulted from differences in the levels of relative humidity between constant and fluctuating temperature regimes. Possible practical use of the model is discussed.