| Root-knot nematodes(RKN),Meloidogyne spp.,are important plant pathogenic nematodes.Their hosts are very wide,can parasite more than 5500 plant species.Meanwhile,RKN are responsible for global agricultural losses amounting to an estimated 1 billion dollars annually.Recently,both the greenhouse acreage and cropping index are increasing,for these the plant disease caused by RKN also increasing severely,especially in vegetable production.Chemical nematicides are commonly used to control the RKN disease that threatens the food and environmental safeties.It is the highlight time to reduce the use of chemical nematicides in controlling RKN disease.In order to solve this problem,the present study tried to explore technologies of reducing the dose of chemical nematicides to control the vegetable root-knot nematode disease.And we got some conclusions:1.RKN underwent several generations in Wuhan greenhouse annually,and overlapping generations of RKN was observed.In addition,the RKN generation duration was closely related to the soil temperature.When the average temperature of soil was more than 24?,the RKN generation duration was 30 days approximately,and it would be extended in corresponding when the soil average temperature was less than 24?.2.Different amount of RKN initial population density resulted in diverse effects of RKN infection on cucumber growth.With the increase of RKN initial population density,the root weight and the number of root knot were both increased,whereas the height,fresh weight and root length were all decreased.When the initial inoculation density of RKN reached 8 second-stage juveniles(J2)per 100 mL soil,the growth of cucumber would be affected significantly.In this study,we found that the increase of RKN initial population density(Pi)led to the increase of the final RKN population density(Pf)in soil after 60 days,but the trend decreased gradually with the increase of Pi.However,the relationship between Pi and reproduction rate fitted to a negative potential function and the maximum reproduction rate of RKN on cucumber was 455.3.In the study,the efficacies of mixed applications of Purpureocillium lilacinum and low-dosage nematicides to control RKN disease were evaluated in the laboratory and field conditions.Mycelium extension and spore germination of P.lilcacinum was not impaired after mixing with low-dosage Fosthiazate(100 ?g/mL).Then the lethal rates of RKN J2 were compared after being treated with P.lilacinum,Fosthiazate and both of them,respectively.The results showed that mixed-application of P.lilacinum and low-dose Fosthiazate exhibited significant higher lethality rate of RKN than they were used alone.After mixing with P.lilacinum granule,the application amount of nematicides Avermectin and Fosthiazate was reduced by 25%and 50%without impairing their efficacy of RKN control,respectively.These results suggested that mixed-application of nematicides and the biocontrol fungus P.lilacinum could be an efficient approach to reduce the amount of chemical nematicides to control RKN.On the other hand,low-dose netamicides could be used to sthrengthen the stability and efficacy of P.lilacinum to control RKN.In summary,this study shows an efficient alternative strategy to control nematode with less chemical namaticides.4.This research has proposed a type of P.lilacinum seed coatings(SC)and found that there was no significant effect on wheat and pea seed germination and their seedling growth.In the pot experiment,the P.lilacinum SC could control the cucumber root knot nematode disease effectively,with the efficacy being 37%.In addition,we also found in the pot experiment that the P.lilacinum SC could increase the plant height,fresh weight and root length as well as the yield of pea significantly,and reduce the pea root knot index with the control efficacy of being about 60%. |
PDF Full Text Request