Severe occurrence of root-knot disease of Lablab sp. was found in Fujian Province, China.The galls on roots of Lablab sp. tend to be large containing hundreds of females. Egg masses were deposited within the gall. Based on morphological characteristics and regions of rRNA ITS sequences, the root-knot nematode on Lablab sp. identified as Meloidogyne incognita. This is the first report that Lablab sp. was infested by root-knot nematode and it was the new record host for M. incognita. The results of inoculation showed that second-stage juveniles of root-knot nematode usually penetrated the root-tip of Lablab sp., but also penetrated the other sites of roots. Egg masses produced by matured females were entirely embedded in the root. After hatching inside the root, secondary infections of the second juveniles may take place in the root-knot. The root-knot induecd by root-knot nematodes developed rapidly to large galls. The male could be found only in decaying root at late growth stage of root-knot. The shortest life cycle was completed in 24 days at an ambient temperatures of 24-36 X,. Common occurrence of root-knot disease of Alternanthera philoxeroides was also found in the field of Lablab sp. The root-knot nematode on A. philoxeroides was identified as M. incognit base on morphological characteristics. The field investigation and cross-inoculation experiments showed that the root knot nematode of A. philoxeroides was the primary source of root-knot nematode disease of Lablab sp. in the field.%在福建省发现豆科新品种多年生藤本豆(Lablab sp.)发生严重的根结线虫病,根部可产生巨大根结,根结内组织内可埋生数以百计的雌虫,卵囊产于根结内.通过形态特征及rDNA-ITS区序列扩增比对,藤本豆根结线虫鉴定为南方根结线虫(Meloidogyne incognita).多年生藤本豆受根结线虫为害为首次记述,也是南方根结线虫新寄主.接种实验结果表明,2龄幼虫主要侵染藤本豆根尖,也可侵染根其他部位,雌虫与卵囊埋生于根结内,卵可直接孵化并在根内直接侵染发育,根结大小发展快,根结坚硬,表面组织不易腐解,雄虫只能在后期根结腐败组织处发现.在环境温度(24～36℃),生活史最短为24d.田间重要杂草空心莲子草(Alternanthera philoxeroides)根结线虫病发生普遍,形态特征鉴定为南方根结线虫,田间调查及交叉接种实验表明其可能为田间藤本豆根结线虫病的主要侵染来源.
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