In 2016-2017,the investigation of the damage degree of vegetable root-knot nematode disease in the main vegetable-producing areas in Tianjin was conducted. The Jinghai District,Xiqing District,Wuqing District,Baodi District,Yinzhou District and Beichen District in Tianjin City were investigated. The vegetable cucumber greenhouse in the district was the object of study and systematically studied the occurrence regularity of root knot nematodes in the greenhouse. The results showed that the root-knot nematode...