Molecular Identification And Control Test Of Root-knot Nematodes In Main Rice Producing Areas Of China

Root knot nematode is one of the main diseases of rice and vegetables in China.Root knot nematodes(Meloidogyne spp.)are widely distributed in China.In this study,(I)1309 paddy soil samples from 53 cities(districts /counties)of 17 provinces(municipalities)were collected for biological detection to determine the occurrence of root knot nematodes.(2)Molecular identification of positive samples in the biological detection was carried out to identify the species.(3)6 nematicides or compound were tested for their efficiency to control the root-knot nematode in the rice nursery.The results showed that:1.316 soil samples had root-knot nematodes,and the positive incidence was 24.14%.Except for Shandong province,soil samples from other 16 provinces all can cause root knots in either rice or tomato roots.Among them,the detection rate of soil samples from Guangxi was the highest,reaching at56.67%;the detection rate of soil samples from Fujian was 53.08%;the detection rates of soil samples from Guangdong,Hunan and Zhejiang were41.67%,42.73% and 45.00%,respectively;the detection rates of soil samples from Hainan and Anhui were 22.22% and 23.33,respectively;the detection rates of soil samples from Chongqing,Guizhou,Jiangxi,Hubei and Yunnan were between 10%-20%;the detection rates of soil samples from Shanghai,Jiangsu,Henan and Sichuan were all lower than 10%.2.Among the 316 positive soil samples in the bioassay,253 samples were successfully extracted DNA,while 173 soil samples were detected by at least one tested root-knot nematode.Six species of root knot nematodes were identified in the 173 soil samples,they were:Meloidogyne graminicola,M.hapla,M.incognita,M.enterolobii,M.javanica and M.arenaria,the detection rates were respectively of 89.02%,41.62%,4.05%,4.05%,10.40% and 30.06%.M.graminicola was the dominant species in the detected samples.Among them,two species were detected in Sichuan Province,Guizhou Province,Hubei Province and Jiangxi Province;three species were detected in Chongqing,Guangdong Province,Anhui Province,Shanghai city and Jiangsu Province;four species were detected in Henan Province,Guangxi Autonomous Region and Hainan Province;five provinces were detected in Zhejiang Province and Hunan Province;six species were detected in Yunnan Province and Fujian Province.3.Among the six treatments,the mixture of avermectin and thiazophos had the best control effect on rice root knot nematode,with the control effect of 85.37%.Only andaxing herbicide had the control effect on rice root knot nematode,with the control effect of 54.71%.The mixture of avermectin,thiazophos and self-made avermectin and thiazophos could affect the seedling emergence rate.The emergence rate of the mixed granule with herbicide was lower than that of the blank control.It was also found that abamectin thiazoline compound granules,which had no herbicidal components,also had inhibitory effect on weeds,and the weed control effect was 55.99%.