| 北京地区春玉米螟害产量损失估计方法及防治指标的商榷 |
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| 引用本文： | 吴维均,严毓骅,蔡宁华.北京地区春玉米螟害产量损失估计方法及防治指标的商榷[J].植物保护学报,1965,4(4):323-328. |
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| 作者姓名： | 吴维均 严毓骅 蔡宁华 |
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| 作者单位： | 北京农业大学，北京农业大学，北京农业大学 |
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| 摘 要： | 根据1962—1964年北京地区12块春播玉米地心叶期卵和卵虫(第一代)成活率資料,并参考国内对螟害与玉米产量損失关系的研究成果,提出了春玉米上因玉米螟为害而造成的产量損夫估計方法和药剂防治的参考指标。心叶期卵的平均成活率及其标准誤为57.4±2.9％,卵块的脫落是死亡的主要原因。幼虫期的平均成活率及其标准誤为5.64±0.89％。这两个平均成活率的变異系数都比较小,相关分析表明,百株着卵量与成长幼虫数是相关的。故可职利用卵和幼虫的平均成活率由着卵密度来估計成长幼虫密度。心叶期卵和幼虫的合計平均成活率及其标准誤为3.4±0.51％。在95％可靠性时的置信区間为3.4±1.173％,卵块的平均粒数为31.7粒。若职单株平均一虫所造成的产量損失率为5％計,可用丁式来估計产量損失: 产量損失％=(心叶期百株累計卵块数×31.7)×(0.034±0.012)]×0.05 在經济核算士,作者初步認为职損失率1.5％作为防治标准比較合适。以此推算,欲达到这一損失率,心叶期百株累計卵块应为28块(用平均成活率計算)至21块(用成活率上界計算)。一般可定为24块。根据心叶期百株累計卵块数与累計着卵株百分率或百株高峯卵块数之間存在的相关,百株累計24块卵,相当于累計着卵株率28％,或百株高峯卵块6块。在实践上就可以用它們作为心叶期的防治指标。
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A DISCUSSION ON THE METHOD FOR ESTIMATING YIELD LOSS CAUSED BY THE EUROPEAN CORN BORER (OSTRINIA NUBILALIS HÜBN.) AND CONTROL INDEX AT WHORL STAGE OF SPRING-SOWN CORN IN PEKING |
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| Woo Wei-ch&#;n,Yien Y&#;-hua and Tsai Ning-hua.A DISCUSSION ON THE METHOD FOR ESTIMATING YIELD LOSS CAUSED BY THE EUROPEAN CORN BORER (OSTRINIA NUBILALIS HÜBN.) AND CONTROL INDEX AT WHORL STAGE OF SPRING-SOWN CORN IN PEKING[J].Acta Phytophylacica Sinica,1965,4(4):323-328. |
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| Authors: | Woo Wei-ch&#;n Yien Y&#;-hua and Tsai Ning-hua |
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| Institution: | Peking Agricultural University,Peking Agricultural University and Peking Agricultural University |
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| Abstract: | Studies were carried out in Peking during 1962-1964 to investigate the mortalities of egg and larval stages and the relationship between the number of egg masses and the size of larval populations in a total of 12 fields of spring-sown corn during the whorl-stage. On the basis of the survival rates of both egg and larval stages of these fields as well as data on the effect of larval density on yield loss, a method for estimating yield loss caused by corn borer and the control index at whorl-stage were discussed. The following points are shown. (1) The 12 fields observed during the 3 year period showed a fairly wide range of egg and larval populations. These variations were due to the fluctuation in natural borer population in different years and the different planting dates in a given year. (2) The mean and its standard error of the per cent eggs hatched was 57.M 2.9%. while that of the larval survival rate was 5.64M0.89%. A measure of correlation showed that the number of eggs per 100 plants is positively correlated with the number of mature larvae. The comlimed survival rate and its standard error of both egg and larval populations was 3.4M0.51%. The flducial limits of the mean at a confidence level of 95% is 3.4M1.17%. (3) Current studies on the relationship between borer population and yield loss of corn by various workers have shown that the reduction in yield of corn infested at whorl-stage was sigficantly greater than that of the ear-stage. Thus the loss in yield due to borer infestation could generally estimated from records on the number of borers of the first generation. If the 5% loss in yield per borer per plant was used as an average reduction rate, then the loss in yield from an infestation having a particular egg mass count could be estimated by yield loss (%)=(No. egg masses per 100plants× 31.7)× (0.034M0.012)] × 0.05 where 31.7 is the average number of eggs per egg mass. From the view-point of economic gain, a reduction rate of 1.5% probably will be valid as the critical control level, i. e., above which treatments should be made. The cumulative total number of egg masses per 100 plants that corresponds to this reduction rate is roughly 24. (4) The present writer have previously shown that the cumulative total of egg masses per 100 plants (X) during entire whorl stage is proportional both to the per cent of plants receiving one or more egg masses or the frequency index (P) (P=le-0.00985x0.9984) and the highest number of egg masses found on any one day (Y) (Y=0.352x-2.721). On the basis of these equations, it is calculated that this egg mass count corresponds to a frequency index of 21% or a number of 6 egg masses per 100 plants at the peak of egg deposition. Therefore, either a frequency index of 21% or a 6 egg masses count found at any one day during whorl stage may be used as an critical index for insecticidal treatment. |
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