Studies On Distribution And Effect Factors Of Dominance Soil Nematodes In Shanghai And Relation Of Fusarium Oxysporum F.sp Niveum

To survey soil dominant nematodes species and distribution of watermelon root in Shanghai, and investigate the relation between plant nematodes and Fusarium oxysporum f.sp niveum.Investigation shows: One of plant parasitic nematodes, 6 species belonging to 5 genera were found. They were Filenchus, Psilenchus hilarulus, Meloidogyne incognita, Tetylenchus and Helicotylenchus. One of fungal feeding nematodes was only found Aphelenchus avenae. The other was Rhabdididae nematodes and else. Among them, Aphelenchus distributed 5 soil type, sharing to investigate 38.1% that the total kind order, accounting for 4.7% of investigate total amount; Filenchus six soil type all distributed, sharing to investigate 33.3% that the total kind order, accounting for 1.1% of investigate total amount; Psilenchus and Meloidogyne incognita were distributed in green purple mire and yellow mire, accounting for 9.5% and 14.2% of investigating total kind respectively, accounting for 1.8% and 0.7% of investigating total amount. Rhabdididae and other nematodes were distributed all collection spot and accounted for 91.6% of investigating total amount.The nematode high peak period was in every year April to July. The first peak was focused on April and May. The second was centralized June and July. The different rotate can effectual control nematode quantity. In this trial corn-watermelon and melon-tree and melon-vegetables rotates can control nematodes quantity at certainty degree, and effectual prevent the occurrence of the nematode high peak period. See from the soil type, From analysis of the soil humidity, the high humidity restrain nematodes amount, but the lower humidity such as 5% can be advantageous to the growth of the nematode.Making use of inhibition of different fungicides and nematicides against Fusarium oxysporum f.sp niveum mycelial growth and nematodes, toxicity determination of single and mixture fungicides in controlling Fusarium oxysporum and nematodes had been done. The calcium cyanamide and avermectin were the best among three nematicides, effective concentration(EC₅₀) of them were 1.1473 and 6.6416μg/ml, respectively. The prochloraz and carbendazim and thiophanate-methyl were fungicides, effective concentration(EC₅₀) of them to inhibit the growth hypha were 10.9898,17.6795 and 62.9859μg/ml, respectively. Avermectin-carbendazim were screened to mixed at different ratio. Comparing with their CTC which were calculated by Yun-peisun formula. The result showed 1/1 mixed ratio was the best. The CTC of it to Fusarium oxysporum f.sp niveum was 172.74 and to nematodes was 109.86. The CTCs of them were above 100 and had synergia to some extent.Soil nematodes and Fusarium oxysporum f.sp niveum was a positive correlativity. From farmland experiment, result showed: the defensiveness effect of mixture was better than single. In two kinds of processing, the medicine soil processing was compare to irrigation to be a good. The defensiveness effect of medicine soil processing to nematodes was 28.9%,52.6%,58.9%, respectively. But irrigation was10.5%,24.2%,39.5%, respectively. The same result as integrated prevent. There was no evidence diversity between using nematicide and CK in zoology control. From field experiment in Shanghai, it showed the calcium cyanamide- carbendazim-phoxim and cyanamide-phoxim processing had a effect controlling. The reduction ratio of nematodes amout was over 80%.