Detection, Virulence Differentiation And Control Of Root-knot Nematodes On Vegetables

Root-knot nematodes (Meloidogyne spp.) are group of plant parasitic nematodes that are economically important. Five root-knot nematode species, M. incognita, M. javanica, M. arenaria, M. haplaand M. enterolobii, can cause great loss of agricultural crops in China. This study mainly focus on morphological and molecular detection of Meloidogyne spp. on vegetables from southeast China, virulence differentiation of M. incognita populations and comparision of the validity and persistence of common nematicides.The main results as follows:Eighteen root-knot nematode samples from vegetables and/or weeds in Zhejiang, Fujian and Yunnan provinces were identified based on morphological and molecular methods using combined Multiplex PCR with SCAR-PCR. Mixed infection of M. incognita and M. javanica were observed occurring in Taizhou, Hangzhou and Yongjia, Zhejiang province wherein M.incognita is recorded as abundant species. On the other hand, M. incognita was found affecting mostly in carrot crops in Zhangzhou, Fujian province while M. incognita, M. javanica, M. enterolobiiand M. haplawere detected in one sample from Yuanmou, Yunnan province.Pathogenicity test were done accordingly to3M. incognita populations of Zhejiang province (Hangzhou, Yongjia and Xiaoshan) againts4resistant tomato cultivars namely’ChunzhanNo7’,’ChunzhanNo8’,’XiankeNo1’ and ’XianchongjueNo1’. It was indicated that:’ChunzhanNo7’,’ChunzhanNo8’ and ’XiankeNo1’ showed low resistance to Hangzhou population, while’XianchongjueNo1’observed to be highly resistant.’ChunzhanNo7’ and ’ChunzhanNo8’ showed highly resistant to Xiaoshan population, while ’XiankeNo1’ and ’XianchongjueNo1’ showed low resistance while ’ChunzhanNo7’,’ChunzhanNo8’ and ’XianchongjueNo1’ showed highly resistant to Yongjia population, while’XiankeNo1’showed only low resistance.Using gradient inoculation test of M. incognita on tomato cultivar’Zhefen205’, it was observed that plant height, fresh weight and dry weight decreases with the increase of inoculums (8000J2inoculum per plant) showing a large drop of biological indicators, severe damaged, fresh weight reduced by69.8%, dry weight reduced by66.8%. Moreover, the number of eggs in single egg-mass and reproduction coefficient all decreases with the increase of inoculums. With1000J2inoculum,531eggs in single egg-mass were recorded, reproduction coefficient is14.8%, which were significantly higher than other treatments. While with8000J2inoculum, the number of eggs in single egg-mass and reproduction coefficient are306and8.5%, respectively.The validity and persistence of7nematicides namely Dazomet, Fosthiazate, Abamectin, Ethoprophos, Hongtuyun, NingdunNo.1and Yishengyuan to cucumber root-knot nematodes were tested twice in the greenhouse from2013-2014.In addition, a field resistant test was made using Gynura bicoloragainstcucumber root-knot nematodes. The results revealed that Dazomet and Fosthiazate showed stable efficacy and long validity in control of cucumber root-knot nematodes. In2013, the control effect of Dazomet and Fosthiazate reaches75.1%and72.6%, while Abamectin, Ethoprophos and Hongtuyun were20.4%,42.8%and45.2%respectively. In2014, the control effect of Dazomet and Fosthiazate were66.3%and53.2, while Abamectin, Ethoprophos, Hongtuyun, Ningdun1and Yishengyuan were21.5%,25.1%,13.3%,33.8%and19.4%, respectively. While test of Gynura bicolorshowed obvious field resistance to cucumber root-knot nematodes, and thus considered a potential resistant resource.