In the present paper, the actions of root-lesion nematodes,
Pratylenchus spp., responses to
Fusarium spp. in the soil were observed.
(1) When the colony of
Fusarium spp. was inoculated into soil infested with
P. penetrans homogeneously, the nematode distributions varied ununiformly, and nematodes accumulated within the soil block (Sample A) which existed about the fungus colony; the most extreme occurred when
F. oxysporum was inoculated. Ratio of nematodes recovered from Sample A increased 69.2% compared with 50.0% in check 144 hours after inoculation. When
F. oxysporum f.
lycopersici or
F. roseum f.
cerealis was inoculated, the accumulations of nematode in Sample A were lower than when
F. oxysporum was present.
When the colony of
Fusarium sp. was inoculated into soil infested with
P. coffeae, the nematode distributions varied similarly as in the former results, and the ratio of nematodes recovered from Sample A increased 73.0%.
(2) When the culture filtrate of
Fusarium spp. was inoculated into soil infested with
P. penetrans, the nematode distributions varied ununiformly, and the accumulations of nematode occurred in the soil block (Sample A') which existed about the culture filtrate of
F. oxysporum or
F. roseum f.
cerealis. Ratio of nematodes recovered from Sample A' increased 68.3% to
F. oxysporum and 62.0% to
F. roseum f.
cerealis 144 hours after inoculation.
(3) When the colony of
Fusarium spp. and the suspension of
P. penetrans were inoculated in each different position of sterilized soil simultaneously, the nematodes responsed to existing fungus and the actions were the most extreme when
F. oxysporum was used. Ratio of nematodes recovered from the soil block (Sample B") which existed about the colony of
F. oxysporum increased 35.7% compared with 16.3% in check 144 hours after inoculation. The actions of nematode to
F. roseum f.
cerealis were milder than those to
F. oxysporum, and the ratio of nematodes recovered from Sample B" indicated 25.8%.
When
Fusarium sp. and
P. coffeae were inoculated into sterilized soil as formerly described, the actions of nematode to
Fusarium sp, were extreme and the ratio of nematodes recovered from Sample B" increased 36.1% compared with 15.2% in check.
(4) When the culture filtrate of
Fusarium spp. and the suspension of
P. penetrans were inoculated in each different position of sterilized soil simultaneously, the actions of nematode to
Fusarium spp. showed the same tendency as when fungus colony was inoculated, but they were milder generally.
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