青割玉米台南19號上螟蟲防治基準之訂定

Determination of Economic Injury Level for the Asian Corn Borer on Silage Corn Tainan No. 19

曾清田(C. T. Tseng) ； 吳炎融(Y. Z. Wu)

《臺南區農業改良場研究彙報》 35期 (1998/12) Pp. 65-72

https://doi.org/10.29558/XLZY.199812.0005

摘要

本試驗旨在探討青割玉米「台南19號」，在不同期作及生育期之玉米螟經濟危害基準，藉供農友防治該蟲之參考。本試驗於84年秋作及85年春作各舉行一次，于玉米生育至第6、第8、第10及第12葉齡時分別接種卵塊，每株平均接種0.0（對照）、0.1、0.2、0.4、0.8及1.6卵塊，結果顯示植株被害率，蟲孔數及蟲孔長度均隨接種卵塊數之增加而遞增。而公頃鮮草產量則隨接種卵塊數之增加而遞減。其所造成之經濟損失，84年秋作于第6、第8葉齡接種0.2卵塊╱株、第10葉齡接種0.8卵塊╱株、第12葉齡接種0.4卵塊╱株，85年春作在第6、第8及第10葉齡接種0.1卵塊╱株，第12葉齡接種0.2卵塊╱株時，已相當或超過每公頃防治玉米螟一次所需費用3,170元。其中秋作第6及第8葉齡每株接種0.2卵塊與春作第8葉齡接種0.1卵塊造成之經濟損失值，超過公頃防治玉米螟費用3,170元達三分之一至五分之三。為避免損失，在此生育期間卵塊發生密度達此數量前，即應採取防治措施。因此秋作平均每株螟蟲卵塊發生數在第6、第8葉齡達0.2卵塊前，第10葉齡達0.8卵塊、第12葉齡達0.4卵塊，春作第6及第10葉齡達0.1卵塊，第8葉齡達0.1卵塊前，第12葉齡達0.2卵塊時，即為青割玉米「台南19號」上螟蟲之防治基準。接種卵塊數與植株被害率、蟲孔數、蟲孔長度及鮮草產量之相關值分析結果，顯示除春作接種卵塊數與植株被害率及春作第6葉齡接種卵塊數與蟲孔數、蟲孔長度及鮮草產量之相關值未達顯著水準外，其餘各相關值均達顯著性水準。顯示玉米螟卵塊發生數量可做為預測該蟲經濟危害青割玉米「台南19號」之指標。

關鍵字

青割玉米 ； 玉米螟 ； 經濟危害基準

並列摘要

The objective of this study is to determine the economic injury level for the Asian corn borer Ostrinia furnacalis on various growing stages of silage corn Tainan No. 19 planted in different crop seasons as a criterion for applying control measures at proper time. This study was conducted in fall crop 1995 and spring crop 1996. The growing stages selected for artificial infestation were the 6th, 8th, 10th and 12nd leaf stages. The numbers of corn borer egg masses infested per plant in each leaf stage were 0.0, 0.1, 0.2, 0.4, 0.8, 1.6. The experimental results revealed that the artificial infestation with 0.2 egg masses per plant at the 6ht and 8th leaf stages and 0.8 egg masses per plant at the 10th leaf stage and 0.4 egg masses per plant at the 12ed leaf stage in fall crop, 0.1 egg masses per plant at the 6th, 8th , 10th leaf stages and 0.2 egg masses per plant at the 12nd leaf stage in spring crop the economic losses caused to silage corn Tainan No. 19 were almost equal to or over the corn borer control cost per hectare. But among them at the 6th and 8th leaf stages infested with 0.2 egg masses per plant in fall crop and at the 8th leaf stages infested with 0.1 egg masses per plant in spring crop the economic losses were more than the corn borer control cost per hectare by 1/3 to 3/5. In other words, the economic injury level for the Asian corn borer on silage corn Tainan No. 19 is before 0.2 egg masses per plant at the 6th and 8th leaf stage, 0.8 egg masses per plant at the 10th leaf stage and 0.4 egg masses per plant at the 12nd leaf stage in fall crop, 0.1 egg masses per plant at the 6th and 10th leaf stage, before 0.1 egg masses per plant at the 8th leaf stage, and 0.2 egg masses per plant at 12nd leaf stage in spring crop. The correlation coefficients between the number of egg masses infested per plant at the 6th, 8th, 10th and 12nd leaf stages and percent damaged plant, No. of cavities per plant, length of cavities per plant and straw yield per hectare are all significant different, except those with percent damaged plant in spring crop, and those with no of cavities per plant, length of cavities per plant and straw yield per hectare at the 6th leaf stage in spring crop. This is indicated that the number of corn borer egg masses on corn plants from the 6th to 12nd leaf stages in both fall and spring crop seasons could be ussed as an index to correlate it with the economic losses on silage corn Tainan No. 19.

並列關鍵字

Silage corn ； Corn borer ； Economic injury level