柑桔潜叶蛾对柑桔的为害及经济阈值的研究

调查福州市郊柑桔园柑桔潜叶蛾（Ｐｈｙｌｏｃｎｉｓｔｉｓｃｉｔｒｅｌａ）在雪柑、芦柑、蕉柑、福桔４个品种上的为害情况．根据其为害特性和柑桔果实产量大小年份可能给经济阈值带来的误差，采用同一树上以秋梢为计量单位，环割被测枝条（避免枝条间养分重新分配而带来误差）的方法，研究了为害秋梢的叶片光合作用强度，当年和翌年春夏梢的生长量，翌年果实品质和重量，以及叶片被害程度与柑桔潜叶蛾幼虫密度的关系．结果表明，柑桔受潜叶蛾为害后具有一定的光合补偿及组织愈伤的补偿能力；根据福州地区１９９４年柑桔生产力，以雪柑为品种确定经济阈值为１．２１头１龄幼虫／嫩叶；缩小了经济阈值受果实产量大小年份差异而带来的误差；同时考虑品种、柑桔园水热条件、产量水平、天敌作用等多种生态因子，建立了多因子经济阈值模型

Damage of citrus leafminer to citrus and its economic threshold.

The damage of citrus leafminer ( Phyllocnistis citrella ) to four citrus varieties (Xuegan, Rugan, Jiaogan, and Fujue) was investigated at citrus garden in Fuzhou suburbs from September 1993 to December 1994. Because the errors in economic threshold could be produced by different damage figures and annual fluctuation of citrus yield, the autumnal treetops were adopted as numerating units, and the determined twigs were rooundly cut. The photosynthesis intensity of leaves damaged by leafminer, the growth of the damaged autumnal treetops in current year and the vernal and autumnal treetops in second year, the fruit quality and quantity in second year, and the relationship between the damage degree of leaves and the density of leafminer population were studied. The results show that after damaged by leafminer, the leaves had certain compensation abilities in photosynthesis and tissue concrescence. According to the production level of citrus in Fuzhou in 1994, the economic threshold on Xuegan was set at 1.21 larvae of first instar per tender leaf, which reduced the errors in economic threshold produced by annual fluctuation of citrus yield. Based on several ecological factors, e.g. citrus varieties, hydrothermic conditions in citrus garden, yield and natural enemies, a multi factor economic threshold model was established.