棉蚜防治指标的研究

通过三年多点田间小区对比试验,组建了棉蚜危害棉花1～3叶期、4～8叶期和伏蚜期棉花卷叶株率(x)和产量损失率(y)的回归式,分别为y=20.021e~(-8.9287/x)(n=29,r=0.8066,p<0.001)、y=19.925e~(-13.3779/x)(n=19,r=0.9006,p<0.001)和y=23.272e~(-12.2155/x)(n=12,r=0.7469,p<0.01)。结合目前我省棉花产量水平(亩产120～150斤皮棉)、防治费用等,提出上述三个时期棉蚜的防治指标分别为卷叶株率4～5%、7～8%和7～8%,均较我省过去的防治指标有所放宽。

STUDIES ON THE CONTROL CRITERIA OF COTTON APHIS (APHIS GOSSYPII GLOVER)

Cotton aphis is the most destructive pest of cotton at the early and middle growth stages of cotton in Shandong Province. The damage caused by cotton aphis and its control criteria were studied during 1983-1985 in Pingyuan, Dezhou, Zhucheng and Linqing counties.These experiments were conducted in field plots as well as in the fields. We used the percentage of curly-leaf plants as the index of control criteria during stages 1-3 leaves, 4-8 leaves and "summer aphid", because this index not only can indicate the relativity with the aphid number correctly, but also save labour to count the aphis.The result obtained has showed that the percentage of curly-leaf plants and the percentage of yield reduction at three cotton growth stages mentioned above can be expressed as y=20.021e~(-809287/x),y=19.925e~(13.3779/x),y=23.272e~(-12.2155/x) According to the cost and the efficiency of control, the yield and the price of ginned cotton, and the critical factor, we consulted the yield level of the cotton crop in Shandong Province (120-150 jin per mu) and used these regression equations to account these control criteria as follows: the percentage of curly-leaf plants 4-5% at stages 1-3 leaves, 7-8% at stages 4-8 leaves and "summer aphid".