• 作者： 杜金池; 張義璋; 王仲文
• 作者服務機構： 臺灣省農業試驗所
• 中文摘要： 1.水稻插秧後一邊個月內，水面普遍漂浮有大量菌核，平均每十天每個 112.5 cm 菌核捕集網，在屏東地區稻田於第一期作捕率25個菌核，第二期作 79.4 個菌核，臺中地區第一期作捕獲78個菌核，第二期作22個菌核。 2.屏東地區於第二期稻作收穫後，於一個月後調查結果，發現遺留在田間殘稻叢每叢平均附有15.4個菌核，如以每公頃200,000叢計算，菌核數將達約 31×10 之多。 3.在自然環境下置於表土之紋枯病原菌菌核壽命達十六個月以上。埋於土內 2cm 以下時壽命將不會超過八個月。 4.紋枯病原菌亦以積極的方式在田問雜草如稗草、黃花水丁香、三稜草、Lindernia cor-difolia 及 Rotala indica 等行寄生生存，更容易在科草病株上產生菌核。另外也在冬季裹作如馬鈴薯上行寄生生存。 5.水稻生育期問對紋枯病之感病性均無差異，供試五品種水稻對紋枯病之感病率一也無差別，但病斑擴展程度則因品種而異，顯示品種問有不同程度的耐病性。 6.氣溫在 28 C 時最適宜紋枯病之發生，12 C 以下不發病。24 C 最適宜病斑擴展，相對濕度81～92％　最適宜，高於 RH 95％ 或低於　RH 65％，均不利於病害之發生。
• 英文摘要： 1. There were a great number of sclerotiafloating on the irrigation water in the paddyfield one month after transplanting. Each112.5cm2 of sclerotium trapping cage caught 25sclerotia every ten days in the first crop of riceand 79.4 sclerotia in the second crop in Ping-tung area, while there were 78 sclerotia in thefirst crop and 22 sclerotia in the second cropin Taichung area. 2. Each stubble of the second crop of ricecarried ca. 15.4 sclerotia in Pingtung area.Thus, it was estimated that approximately 31 x 10 sclerotia were produced in each hectare of field. 3. Sclerotia on the surface of field soilsurvived for longer than 16 months. However,the longevity was lesser than 8 months if theywere buried in soil deeper than 2cm. 4. The pathogen actively survived as a pa-rasite on some paddy weeds, such as Linderniacordifolia, Ludwigia prostata, Rotala indica, Scipusmaritimus and Echinochlora crus-galli. Abundantsclerotia were also produced on diseased plantsof E. crus-galli. It also caused black scurf onpotatoes, which was a winter crop of certainpaddy fields in the Taichung area. 5. Although there was no difference on thesusceptibility to sheath blight among rice varie-ties, the spot size, however, was different amongvarieties. This fact indicated that different de-grees of disease tolerance might be found indifferent varieties. 6. The disease was the most prevalent at28 C. The spot expanded rapidly at 24 C. Nodisease was observed at 12 C. RH 81-92% werethe best conditions for the disease occurrence.Relative humidities higher than 95% and lowerthan 65% were not suitable.
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