(27(4):355-362)Epidemiological studies of rice blast disease observations of 1976 and 1977

臺南5號在第一期稻作會發生葉及穗稻熱病，在65及66年其葉稻熱病之發病寧最高達58.2及40.1%，穗稻熱病之發病率達27.6及40.2%。臺南5號第二期作葉及穗稻熱病發生輕微。嘉農秈8號第一期作及第二期作葉稻熱病發生輕微，但穗稻熱病有時候發生嚴重，65年第一期作穗稻熱病發病率最高達47.2%，第二期作最高達33.6%，葉稻熱病發生前七天的平均溫度在20~25℃之間。臺南5號穗稻熱病發病率受降雨日數的影響，降雨日數越多，發病率越高，葉及穗稻熱病發病率高時，所採集到的胞子數目多，空氣中的胞子從3月到11月上旬之間可以採集得手到。 The leaf and panicle blasts occurred to a high level on Tainan 5 during the first rice crop of 1976 and 1977. The highest incidence of leaf blast recorded was 58.2% and 40.1 % for 1976 and 1977, respectively. The disease incidence of panicle blast was 27.6% and 40.2% for the years, respectively. In the second crop, both leaf and panicle blasts were slight on Tainan 5 for these periods. The leaf blast was slight on Chia-nung-shen 8 in both the first and second crops. But the panicle blast occurred to a level of 47.2% and 33.6%, respectively, in the first and second crops in 1976. However, blast did not occur on Chia-nung-shen 8 in 1977. The average daily temperature of the seven-day period before the first appearance of leaf blast fell in the range of 20-25°C. The panicle blast on Tainan 5 was affected by the number of rainy days. A higher disease incidence was correlated with more rainy days. The blast fungus conidia were trapped to a great number when the incidence of leaf and panicle blasts was high. The conidia could be trapped from the air March to October or to November during the years under the field conditions