In 61 abolished ginseng fields examined in 1986, the average plant missing was 49.2%, root rusting, 34.4%, and root rot, 3.3%, Plant missing was not different among the ages of ginseng fields; however, rate of root rusting was high in 3- and
4-year-old
ginseng fields, and rate of root rot was high in 5- and 6-year-old ginseng fields, suggesting that root rusting and root rot were relatively more important factors related to the abolishement of ginseng filed in younger and older ginseng fields
in
1986,
respectively, Out of 61 ginseng fields, 18 were infested with more than 50% alternaria blights, and out of 19 fields with root rot, 2 were caused by Sclerotinia sp 5 by potato rot nematode, and the causal agents were not identified in 12 fields.
With
increase of the ridge height, root rusting was significantly decreased, and plant missing rate was significantly lower in fields with straw mulching than those without mulching. The physico-chemical characteristics of the fields with more than
50%
root
rusting, the contents of NO3, P2O5 and Ca were higher than those of good fields with less than 40% root rusting and plant missing. The population of Erwinia sp. Was significantly correlaed with plant missing
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