Observation of Root-knot Nematodes in the Root Gall Formed on Oriental Melon

Oriental melon, Cucumis melo L. cv. Geumssaragieuncheon, grafted on Shintozoa (Cucurbit maxima ${\times}$ Cu. moschata) was planted in a greenhouse infested with Meloidogyne arenaria and root galls were examined five months after planting. A gram of root gall was volumed at ca. 10 cm3 and contained in an average of 363 females (170 developing and 193 matured females), 2,120 secondstage juveniles (J2), and 13,074 eggs. In addition, there was 56 J2 per $cm^3$ soil around the infested plant. An oriental melon had an average of 134.6 g of root gall (70% of total root weight) per 0.72 $m^2$ area. In a conservative estimation, an oriental melon plant could accommodate ca. 1.2 ${\times}$ $10^7$ eggs and J2 per 0.72 $m^2$. The eggs contained in root tissues could be an important inoculum source to the next crop and the fate of these eggs are well worth further investigation.