• 作者： 蔡武雄
• 作者服務機構： 臺灣省農業試驗所嘉義分所
• 中文摘要： 本研究在明瞭稻熱病之發生及病勢之進展與溫濕度、露水等環境因子之關係，作為預測稻熱病發生之依據，以便做到適時、適期防治稻熱病。 水稻臺南5號及嘉農秈8號在1月15日插秧，臺南5號葉稻熱病在3月16日（插秧後60天）開始發病，插秧後90天病勢達到最高峰，以後病勢開始下降。嘉農秈8號葉稻熱病發生較遲，在3月28日（插秧後75天）才發現病斑。穗稻熱病均在5月25日開始發生（抽穗後14天），病勢進展到6月6日。臺南5號之葉稻熱病及穗稻熱病發病率各為58.3％及27.6％，而嘉農秈8號之葉稻熱病及穗稻熱病各為2.8％及47.2％。葉稻熱病發生前10天田間即可採集到病菌胞子，但數量不多。第一期作收穫後及第二期作插秧前亦可收集到胞子，其數量不多。 胞子採集量最多時，在發病最高峰及病勢開始下降初期。胞子採集量與露水時間無直接關係，露水時間長，可以採集到甚多的胞子，但沒有露水時也可以收集到很多胞子。第一期作葉稻熱病發生前之平均溫度在20～25℃左右，平均濕度在72.0～77.0％，第二期作雖有葉稻熱病發生，但發病輕微，其平均溫度在30℃左右，平均濕度在81.0～84.5％，每天胞子採集數從午夜到早上九時最多，但遇陰雨天時從九時到十七時也可採到相當多的胞子。R.M及S型病斑數目隨著病勢之進展而消長。
• 英文摘要： The purpose of this study was to detectthe relationships of blast occurrence and diseasedevelopment to the meteorological factors, suchas temperature, relative humidity, dew, etc.The data obtained on this experiment would beused as a guide for predicting the blast diseasein the future, and for protecting rice plants byfungicides at the critical period of time. The test rice plants of Tainan 5 and Chia-nung-shen 8 were transplanted at 15 January.Leaf blast outbreaked on Tainan 5 at 16 March(60 days after transplanting). The disease inci-dence was highest at 90 days after transplanting,and then decreasing gradually. Leaf blast firstoccurred on Chia-nung-shen 8 at 28 March (75days after transplanting). Panicle blast occurredon both varieties at 25 May (14 days afterheading). The leaf blast and panicle blast in-cidences on Tainan 5 were 58.3% and 27.6%respectively, while on Chia-nung-shen 8 were2.8% and 47.2% respectively. The conidia couldbe detected 10 days before the disease occurrence.They could also be trapped during the periodbetween harvesting of first crop and transplan-ting of 2nd crop. Most conidia were collected when thedisease reached its highest incidence and whenit was at the initial decreasing stage. No closerelationship was found between the number ofconidia trapped and the duration of dew period.More conidia were trapped when the dew periodlasted a long time, however, conidia could alsobe trapped when dew did not appear. Theleaf blast occurred at first crop when averagetemperature was around 20-25℃, and averageR.H. was 72.0-77.0%. It occurred lightly whenaverage temperature was around 30℃ andaverage R.H. was 81.0-84.5% in the 2nd crop.The conidia were collected mostly frommidnight to 9 o'clock in the morning and alsofrom 9 to 17 on cloudy days when the diseasewas at the highest incidence. The number of R,M, and S lesions wasfluctuating with the disease development in thefield.
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