Study On Identification And Preliminary Control Of Root-knot Nematodes On Cucurbitaceae Vegetables In Hainan Island

Root-knot nematode, the most important of the plant parasitic nematodes, responsible for billions of dollars losses annually. Root-knot nematodes have an extensive host range, covering more than 3000 host plants which belongs to 114 families. Cucurbitaceae vegetables is an important economic pillar industry in Hainan Island, The output value was more than 6 billion yuan each year. However, root-knot nematodes have become a serious problem for Cucurbitaceae vegetables cultivation. It could infect the Cucurbitaceae vegetables and cause serious loss. Survey of the 19 main vegetables plant areas and all of them have been infected by root-knot nematodes, in which the disease index over 30. Because of geographical and climatic specificity, root-knot nematode species infecting Cucurbitaceae vegetables varies from each other in Hainan Island. So far, the systematical study on root-knot nematodes parasitized on Cucurbitaceae vegetables in Hainan Island has not been reported.The disease was investigated in 18 main Cucurbitaceae vegetables planting areas and 40 samples of root-knot nematode populations were collected in Hainan Island. The samples were separated, purified, cultivated and kept in disinfected soil by potted tomato. A single root-knot nematode egg parasitizing in tomato roots was choice, and 42 purified populations were obtained, which identified preliminary through morphology.The purified culture female was isolated from root-knot nematode populations for extract isozymes by dissecting microscope. Based on the esterase and malate dehydrogenase electrophoresis phenotype reported by Esbenshade et al (1985,1990), there are four kinds of root-knot nematodes could infect Cucurbitaceae vegetables, which 1 species is not common band for the N1a,VS1-S1 model.Used the primers #1108 and #C2F3 designed by Power inl993, mtDNA amplified fragment size of the not Common bands of purified populations was analyzed. The amplified fragment obtained is 0.7Kb. And the mtDNA sequenced and compared with genes from the GenBank. The results show that, the sequence between the NO. GQ870255.1 homology up to 100% which was reported Meloidogyne enterolobii.The results as follows:29 populations have finally been identified as Meloidogyne incognita, accounting for 65.91%, which isozyme types are N1, I1 and amplified fragment length of mtDNA are 1.7kb; 4 populations have been identified as Meloidogyne javanica, accounting for 9.09%, which isozyme types are N1, J3 and amplified fragment length of mtDNA are 1.7kb; 1 populations have been identified as Meloidogyne arenaria, accounting for 2.27%, which isozyme type is N1,A2 and amplified fragment length of mtDNA are 1.1kb; 10 populations has been identified as Meloidogyne enterolobii accounting for 22.73%, which isozyme types are N1a,VS1-S1 and its amplified fragment length of mtDNA is 0.7kb. In the 42 original populations,2 populations are the complex population, which all complexes with Meloidogyne incognita and Meloidogyne enterolobii.Comparison experiment of 6 different nematicides for control Bitter Melon root-knot nematode was conduct in Dingan, Hainan. The results show that,10% Fosthiazate GR and 2.5%Methylene dithiocyanate WP were effective on controlling Bitter Melon root-knot nematodes. They can effectively suppress the number of J2 root-knot nematodes and the formation of the root node in soil.In this paper, Meloidogyne enterolobii have found distributed in 7 cities in Hainan Province, and the dispersion has gradually expanded. Meloidogyne enterolobii has become the second largest population infecting on Cucurbitaceae vegetables. So, we should take attention to when we develop disease resistant varieties and integrated control.