2.病害的综合防治(1)消除田间病残组织,减少菌源:美国参农已充分认识到清除田间病残组织的重要性,注意于秋季清除田间枯死的茎叶,以减少来年叶斑病的初侵染来源,同时也采取严格措施,减少人为传病的可能性。但由于受人力的限制,及时摘除田间早期病叶难以办到。(2)轮作防病:威斯康星州地广,农场占地面积一般都比较大,但一般参农只种植20英亩左右的西洋参,完全有条件轮作,种过西洋参的土地至少在十年内不再种植。这对减轻多种根部病害的危害,是非常有效的。(3)改良田间生态条件,减轻病害:为便于机械化操作,参棚高而间距大,有利于通风排湿。且普遍总行高垄栽培,有利排水,对减轻病害有一定作用。另外,据称调节土壤PH 值至弱酸性(PH 5.5—6.5),对减轻锈腐病有明显效果。(4)土壤消毒处理:美国土地虽多,但考虑到建造参田费工、费时、赞成本,也有人建议通过土壤 2. Comprehensive prevention and control of diseases (1) Elimination of field sick tissues and reduction of bacterial sources: The United States has made full cognition of the importance of removing sick tissues in the field and paid attention to clearing dead leaves and stems in the field in autumn so as to reduce the following year’s leaf spot The source of the initial infection, but also to take strict measures to reduce the possibility of human transmission disease. However, due to the limitation of manpower, it is difficult to timely remove the early diseased leaves in the field. (2) Crop Rotation Prevention: In Wisconsin, the area of ​​the farm is generally large. However, only about 20 acres of American ginseng is planted for agriculture, and the rotation of the cultivated American ginseng is no more than ten years at least . This is very effective in reducing the hazards of various root diseases. (3) to improve the ecological conditions in the field, reduce disease: In order to facilitate the mechanized operation, ginseng studio and high spacing, is conducive to ventilation and drainage. And the general head ridge cultivation, favorable drainage, to reduce disease have a certain effect. In addition, alleged regulation of soil PH value to weak acid (PH 5.5-6.5), to reduce the rust rot has a significant effect. (4) soil disinfection: Although the United States has many land, but taking into account the construction of field labor, time-consuming, in favor of this proposal, it was also suggested that soil