Abstract
The distribution of root-knot nematodes was surveyed in tobacco fields of Japan. In 1992 and 1994, 219 populations of root-knot nematodes in tobacco fields covering the northern most area of Honshu to the Ryukyu Is. were identified on isozyme patterns of esterase and malate dehydrogenase. In this work, four Maloidogyne species, M. incognita, M. arenaria, M. hapla and M. javanica, were found. In M. arenaria, two distinct esterase phenotypes, one (A-1) and two (A-2) band types, were found. Meloidogyne incognita was widely found from southern Tohoku to the Shinetsu districts and southward to the Ryukyu Is. This species was recorded for the first time in Gifu, Nagano, Fukushima, Yamagata and Miyagi Prefs. Meloidogyne arenaria (A-2) was widely found from the Ryukyu Is. to Akita and Iwate Prefs., however, its distribution in Kyushu and the Ryukyu Is. was patchy. This species was found for the first time in Akita and Iwate Prefs. Meloidogyne arenaria (A-1) was mainly concentrated in Kyushu and the Ryukyu Is., and was found in one locality in Shikoku. Meloidogyne hapla was distributed from Shinetsu to the Kanto distinct northward to Aomori Pref. Meloidogyne javanica was found only in the Ryukyu Is. In areas where the distribution of these species overlapped, two or three species were often found in a single field.
