森林的病虫害,是能传播蔓延的。在自然界,林木害虫、病原物(真菌、细菌、病毒等)都有各自的地理分布范围,在一定的范围内,它们可以自身向外传播,如昆虫的飞翔、爬行,菌丝的伸长,孢子的弹射等;也可以借助自然力的传播,如风、雨、流水等把害虫、病菌带到别的地方。不过这种自身和自然力的传播是有限的,范围不广。因为有高山、湖海、沙漠等屏障的阻碍。但是随着社会的发展,贸易往来的增多,运输工具的发达,国与国之间,地区与地区之间调运,交换林木及林产品也日益增多,愈来愈快,那些依附和潜伏在种子苗木上的病虫就能够在短时间内被带到很远的、它们自 Forest pests and diseases, is to spread the spread. In nature, tree pests, pathogens (fungi, bacteria, viruses, etc.) have their own geographical distribution, within a certain range, they can spread themselves, such as insects flying, crawling, mycelium elongation, Spore ejection, etc .; also can use the spread of natural forces, such as wind, rain, running water and other pests, bacteria to other places. However, the spread of self and force is limited and not widespread. Because of the mountains, lakes, desert barriers and other obstacles. However, with the development of society, the increase of trade, the development of means of transport, the transportation between countries and regions and regions, the exchange of trees and forest products is also increasing, getting faster and faster. Those who depend on and lurk in seedlings On the pest can be brought in a very short time, they are