الفهرس 
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Abstract
Tomato is vulnerable to infection by number of diseases, the most important of which are the fungal diseases such as early blight, powdery mildew and late blight. The research aimed to study the relationship between climate change and disease severity for prediction in future seasons. Diseases severity of early blight, late blight and powdery mildew diseases was recorded for three growing seasons i.e. summer (May. - Aug), autumn (Jul. - Oct) and winter (Nov. - Mar.) during the season (2016/2017-2017/2018), at three governorates (Behira, Ismailia, and Assuit). The severity of diseases on tomato has been predicted by regression estimated accumulative disease severity values during (2007/2008) – (2015/2016) seasons and average max and min temperature and humidity through these seasons. Prediction of disease has been formed as Y= b0+b1x1+b2x2+.......... bqxq. Three models were created to describe the severity disease by multiple regressions (MINITAB® program.1995) The highest value of early blight and powdery mildew disease were recorded through the season (2017/2018), while the lowest values were recorded during the season (2016/2017). Also, The highest value of late blight disease was recorded through the season (2016/2017), while the lowest value was recorded during the season (2017/2018). Highly early blight and powdery mildew disease severities were estimated during the summer period compared with autumn and winter growing periods. However, the least severity was estimated through the winter growing period and moderate severity was estimated in the autumn growing period. Also, highly disease severity was recorded during winter seasons compared with autumn and summer growing seasons, but through
summer growing season, the results recorded the least diseases severity while moderately severity was recorded in the autumn growing season. Influence of environmental conditions such as average temperature (daily maximum and minimum temperature) and relative humidity (daily maximum and minimum RH %) on the severity of early blight, late blight and powdery mildew diseases during the seasons (2007/2008) – (2015/2016),showed that the highest severity of early blight was estimated at Assuit governorate (26.9%) compared to Behira and Ismailia governorates, where the mean maximum and minimum temperatures were 31.2 °c and 15.9 °c, respectively and mean percentage of relative humidity was 50.8%. The percentages of explained variances (E.V) for the selected ecological factors at seasons were 45 %, 44% and 68% on the severity of the disease, during (2007/2008) to (2015/2016) seasons, respectively. “F” values were 1.90, 1.85 and 68.58***, respectively. The highest severity of powdery mildew was estimated at Assuit governorate (26.6%) compared to Behira and Ismailia governorates, where the mean maximum and minimum temperature were 31.0 °c and 15.9 °c, respectively and mean percentage of relative humidity was 50.4%. The percentages of explained variances (E.V) for the selected ecological factors at seasons were 60.8 %, 61.5% and 51% on the severity of the disease, during (2007/2008) to (2015/2016) seasons, respectively. “F” values were 3.62*, 3.69 and 1.61, respectively. The highest severity of late blight was estimated at Ismailia governorate (22.6%) compared to Behira and Assuit governorates, where the mean maximum and minimum temperature were 29.1 °c and 16.4 °c, respectively and mean percentage of relative humidity was 60.3%.The percentages of explained variances (E.V) for the selected ecological factors at seasons were 88.2 %, 83.2% and 82% on the severity of infection with the disease, during (2007/2008) to (2015/2016) seasons, respectively. “F” values were 17.36**, 11.58** and 10.42**, respectively. For Forecasting, significantly differences were noticed among disease severity through (2020/2030), (2030/2040) and (2040/ 2050) seasons compared to (2008/2018) seasons and relation with
climate change in tested governorates. Severity of tomato infection with early blight disease may increase from 18.8% to 20.1 during (2008/2018) seasons to (2040/ 2050) seasons at Behira governorate, from 14.8% during (2008/2018) seasons to 36.3% (2040/ 2050) seasons at Ismailia governorate and 23.3% during (2008/2018) seasons to 40.4% (2040/ 2050) seasons at Assuit governorate with slight change in maximum or minimum temperatures and percentage of relative humidity. Severity of tomato powdery mildew disease may increase from 3.3% to 3.5 during (2008/2018) seasons to (2040/ 2050) seasons at Behira governorate, from 7.2% during (2008/2018) seasons to 11.4% (2040/ 2050) seasons at Ismailia governorate and 17.6% during (2008/2018) seasons to 17.9% (2040/ 2050) seasons at Assuit governorate with slight change in maximum or minimum temperatures and percentage of relative humidity. Severity of late blight disease may increase from 3.3% to 3.5 during (2008/2018) seasons to (2040/ 2050) seasons at Behira governorate, from 22.6 during (2008/2018) seasons to 30.9% (2040/ 2050) seasons at Ismailia governorate and 14.6% during (2008/2018) seasons to 5.2% (2040/ 2050) seasons at Assuit governorate with slight change in maximum or minimum temperatures and percentage of relative humidity. Key Words: Tomato (Solanum lycopersicum L., syn. Lycopersicon esculentum Mill.), Early blight, Late blight, Powdery mildew, Climate change, Forecasting,GIS.