中国梨木虱的危害及防治研究*

中国梨木虱喜在隐蔽处危害，造成梨树早期落叶。单叶最大允许虫口密度，叶柄基部为３头，叶片上１０头。以不使全园出现早期落叶树为前提。梨木虱的防治虫口指标为全国平均每叶０．４头若虫。“严冬浇冻水、重点防治第一代若虫和以若虫虫口指标确定防治时期”是目前防治梨木虱经济、高效的防治技术。

Studies on the Damage and Control of Psylla chinesis

The damage and control of Psylla chinesis were studied from 1987 to 1991.The results were as follows:The pear psyllid is one of the main pests of pear trees. Theyfeed on the leaves in concealment.Under serious condition,they can make the leaves fallearlier. The tolerable pest density is 3 on a leaf base and 10 on a leaf blade. This is regaredas the threshold,under which the pests don't cause serious damage. The control thresholdfor the numph is 0.4 on a leaf blade in the whole pear orchard.The field of the orchardshould be irrigated at severe winter. The first-generation nymphs must be controlled.Thetime for control is determined by control threshold. These methods are effective and haveachieved better economic benefit.