Studies On The Root-Knot Nematode Of Siraitia Grosvenorii And Its Control

The root-knot nematode damaged siraitia grosvenorii seriously in Guangxi.The ailing plant's reduction of output was 15～30%,even 50%.The pathogen was identified and the life cycle of pathogen was investigated,further more the control measures including chemic control,microbial control and botanical pesticide were studied.The objective of the study was to develop the integrated management of root-knot nematode of siraitia grosvenorii.1 Identification of pathogen and dynamic of nematode population in the fieldThe species of pathogen was identified as Meloidogyne incognita Chitwood based on morphological characters.The result of the pot inoculating test indicated that the root-knot nematode,Fusarium oxysporum,Fusarium solani,and Verticillium alboatrum can damaged the tubers of Siraitia grosvenorii together in field.When healthy Siraitia grosvenorii plants were inoculated root-knot nematode with the 3 species fungi,the period of illness would be advanced 2 to 6 days and the rate of wilt could be increased 10%to 28%.The seasonal distribution of nematode population in the filed from 0 cm to 60 cm was studied.The result indicate that the most nematodes distribute in the plough layer from 10 cm to 30 cm,which was conform with the roots' distributing of the siraitia grosvenorii in the field,and the population density of nematode reached the peak in the plough layer soil in autumn.2 Compare of the effect of chemical pesticideThe control effect of 7 chemical pesticides which had used in nematode control were conduct to potting experimen.The results indicated that the best inhibitory effect by using chemical pesticides was the Fosthiazate which concentration was 10%and the dosage was 10 g per plant,the prevention and cure effect could reach 91.85%and 85.76%after 30 days and 60 days.3 Biocontrol measure by fungi of Plurotus spTwo species inhibitory activity fungi were screened from 11 fungi by toxicity test in lab,which were Pleurotus corticatus and Plurotus salmoneostram.The corrected mortality of root-knot nematode could reach 92.2%and 91.6%when dealt with extract of those 2 fungi species 48 hours later.Mixed the residues and cultured fungi of Plurotus salmoneostram,and released in field,the amount of Siraitia grosvenorii root-knot nematode could significantly decrease 73.71%and 64.41%respectively in the fastigium of nematode.4 study ofnematocidal plantâ‘ Sapium sebiferum screened out from 15 species plants has good nematocidal effect on Siraitia grosvenorii root-knot nematode.The leaves ethanol extracts of Sapium sebiferum was used in toxicity test and potting experiment.The results shown that the corrected mortality of root-knot nematode J₂ Meloidogyne incognita.could reach 91.94%in dish.The treatment(concentration:2.5g/L,treatment time:48h), which could lead to 93.13%of corrected mortality for J2 Meloidogyne incognita,had the strongest bioactivity among all the treatments,the toxicity regression equations was y=0.4114+1.8191x and LC₅₀ was 333.01mg/L,and the treatment could inhabit 85.59%eggs hatching,the toxicity regression equations was y=2.5183+1.0602x and LC₅₀ was 219.22mg/l.The Meloidogyne incognita was treated with the ethanol extracts from leaves of Sapium sebiferum witch were diluted 100times,1000times and 10000times respectively.The results showed that the mean numbers of root-knots was 12.5±3.84,20.17±4.01,31.8±5.09,which were significantly lower than the control of 5%ethanol(62.5±5.53),the plant height of tomato increased 28.10%,21.07%and 12.23%,and the fresh mass increased33.07%,15.31%and 2.73%compared with the control,respectively.So we can see that the ethanol extract of Sapium sebiferum leaves could significantly decrease the amount of root-knot of tomato plants and effective control the damage caused by root-knot nematode,moreover,it could significantly improve the hieth and weight of tomato above ground,and significantly increase the length of tomato root in pot experiments.â‘¡Through observing the developmental progress of eggs and larvas which were treated with the ethanol extracts from leaves of Sapium sebiferum to study the affection on the embryonic and post-embryonic of nematode.The result indicated that the eggs whitch were treated with the ethanol extracts from leaves of Sapium sebiferum only 15.43%can develop to first age larva,but the 89.43%eggs of antitheses can develop to first age larva.If the young tomatoes were tread with the ethanol extracts from leaves of Sapium sebiferum,juvenile penetration can be prevented 3 days.So,the extract could inhibit the embryonic and post-embryonic of nematode.â‘¢Effects of extracts from leaves of Sapium sebiferum on the Ache activity of Meloidogyne incognita which were studied through "Ellman method".The result indicated that OD of treatment and OD of blank was 0.032 and 0.086 respectively,the two were different significantly.Effects of extracts from leaves of Sapium sebiferum on the Ach content of Meloidogyne incognita which were studied through "hydroxylamine method".The result indicated that the Ach content of the treatment and the blank was 1.6078 mmol/L and 0.2126 mmol/L respectively,the treatment was higher than the blank significantly.In this paper,we found that the ethanol extract of Sapium sebiferum leaves could inhibit the activities of Ache and increase the content of Ach in vivo of root-knot nematode.