Geographical distribution of Heterodera trifolii in eastern Japan

Abstract

The geographical distribution of the clover cyst nematode Heterodera trifolii in eastern Japan on white clover (Trifolium repens) and greenhouse carnation (Dianthus caryophyllus) was surveyed in 2012. A total of 195 and eight soil samples were collected from the rhizospheres of white clover and greenhouse carnation in eastern Japan, respectively. Second-stage juveniles (J2s) of cyst nematodes were detected in 57 of the 195 samples of white clover (29.2%) and five of the eight samples of greenhouse carnation (62.5%) by the Baermann funnel method. The cyst nematodes were identified by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis of the internal transcribed spacer (ITS) region of the nuclear ribosomal RNA (rRNA) gene by using digestion patterns of AluI, MseI, and RsaI. Consequently, H. trifolii was detected from 56 of the 195 samples of white clover (28.7%) and five of the eight samples of greenhouse carnation (62.5%). Our results showed that H. trifolii is widely distributed in eastern Japan and can be potentially a serious threat to carnation production.