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根癌病是一种世界性病害,寄主有59科300多种,主要危害果树,也发生在毛白杨、加杨、大青杨的幼树上,是毛白杨苗期的主要病害之一,为检疫对象。近年来,由于检疫制度不健全,随便由外地引进种苗,使该病迅速蔓延。据我县国营和社队五个单位618亩毛白杨苗圃调查,有539亩已发生根癌病,占总面积的87.2％。其发病程度,病株率1％以下的199亩,1—5％的280亩,6—10％的30亩,10％以上的30亩,个别地块发病率达15％以上。严
Root cancer is a worldwide disease, the host has 59 families more than 300 species, the main damage to fruit trees, also occurred in poplar, Canada poplar, poplar saplings, Populus tomentosa seedling is one of the major diseases, Quarantine object. In recent years, due to the imperfect quarantine system, the introduction of seedlings at any place has rapidly spread the disease. According to the investigation of 618 mu of Populus tomentosa nursery in five units of our county state-owned and social-commune teams, 539 mu of root-knot disease has occurred, accounting for 87.2% of the total area. Its incidence, the diseased plant rate of less than 1% 199 acres, 1-5% of 280 acres, 6-10% of 30 acres, 10% above 30 acres, the individual block incidence rate of 15% or more. strict