| Summary: | 碩士 === 國立中興大學 === 農藝學系所 === 98 === Late blight, one of major crop diseases in the world, is caused by Phytophthora infestans (Mont.) de Bary and is harmful to tomato and potato. Usually, Taiwan is not suitable for the occurrence of late blight owing to high average temperature. However, the emergence of new strain in 1998 lead to late blight to become one of the major diseases of tomato and potato in Taiwan.
According to literatures, weather factors often have great impact on the occurrence of late blight. The climate in Taiwan is usually not apt to the occurrence of late blight, which mainly occurs in the temperature zone. After 1998, the new strain resulted in the large-scale epidemic. It is presumable that the influence of the weather factors for the new strain is different from that of the old one. Thus, it is necessary to investigate the impact of weather on late blight for different weather situation, especially in sub-tropical monsoon climate of Taiwan.
In this study, we have collected recent eight years (2002~2009) field test data of late blight from Taiwan Agricultural Research Institute, Taiwan Seed Improvement and Propagation Station, Pu-Li Branch of Taichung District Agricultural Improvement Station, and Asian Vegetable Research and Development Center (AVRDC). By analyzing the weather factors, we try to find out how the relevant variable affect the outbreak of late blight and its spreading rate.
We have divided the analysis into two parts. The first part focuses on the influence of weather factors to late blight before the disease onset. By temperature, relative humidity, and rainfall, we investigated and evaluated the risk factors of the disease outbreak for the conditions of Taiwan’s climate. The conclusion of the part is that the rainfall has great impact on the outbreak of late blight, and the average temperature should be in the range of 15℃~25℃. The second part is to figure out how the weather factors accelerate or inhibit the spreading of disease after the disease onset. Smooth curves were used in this study to observe the progress of disease versus the weather factors and generalized additive model were performed to account for the progress. We obtained that the temperature and relative moisture have obvious effect on the spreading of late blight. Moreover, the expanding rate of pathogen when the temperature is less than 15℃ than that when the temperature equals to15℃. In addition, it appears that there is a larger range of the temperature after the disease onset.
|
|---|
