我县六十年代以来大搞植树造林,现有四旁树木500万株,人均15.6株。但二十年来绿化事业“三起二落”,病虫为害是造成起而又落的重要原因之一。 1965年全县已栽植苦楝330多万株,1974年开始砍伐利用,但许多地方溃疡病严重发生,不得不将棟树大批砍除,这是第一个起落。1972年引进白榆,深受群众欢迎,到 Since the sixties of our county has vigorously afforestation, the existing four million trees around the trees, 15.6 per capita. However, in the past 20 years, the cause of afforestation has been “falling apart three times” and pest and disease damage is one of the important reasons causing the rise and fall. In 1965, the county had planted more than 330,000 Melphalus strains and started cutting it down in 1974. However, in many places, the occurrence of canker disease has been so severe that it has to be cut off in large numbers. This is the first ups and downs. The introduction of elm in 1972, welcomed by the masses, to