土壤中烟草疫霉的分离与量化测定

从温室盆栽接种试验土和烟田土中分别取样，在室温下晾干，研碎并通过１ｍｍ直径的网筛，用选择性培养基土壤稀释平板法和叶片诱饵法分离烟草疫霉菌株；用土壤稀释平板法测定了云南主要烟区土样的烟草疫霉密度。结果看出，连作烟田的病菌密度高于轮作田，低凹烟田高于山地烟田。叶片诱饵法试验表明，以烟茎切片的诱集效果最好，其次是烟叶和马铃薯叶，番茄叶和辣椒叶的诱发效果相似，花生叶诱集不到烟草疫霉。

Isolation and quantification of soil born Phytophthora parasitica var. nicotianae in tobacco

Samples were collected from soil of inoculation test in greenhouse and natural soil of tobacco field air dried andpassed to 1mm sieve. Phytophthora Parasitica var. nicotianae in the soil was isolated on selective medium with soildilution planting and leaf disks bait methods. Strains of P. Parasitica var. nicotianae can be obtained rapidly withabove methods. Detection and quantification of P. Parasitica var. nicotianae in tobacco field of several regions ofYunnan Province have been done also with soil dilution planting. The result showed that density of the fungus in continous cropping field of tobacco is higher than that of the fungus in the rotation crop field, and the density of the fungus in low land is higher than that of in the highland. Bait experiment on P. parasitica var. nicotianae with different plant leaf disks indicated that bait efficiency of the tobacco stem is the best, leaf disks of tobacco and potato aresecondary, leaf disks of tomato and pepper are similar in bait efficiency. Peanut can not be infected by P. parasiticavar. nicotianae.