沖縄の主要作物の植物寄生性線虫

Abstract

Plant-parasitic nematodes were surveyed covering Okinawa-hontô, Kumejima, Minami'daitojima, Miyakojima and Ishigakijima where annual mean temperatures are 22-23°C. Table 1 shows the genera of plant-parasitic nematodes found in Okinawa region. The genera obtained from soils around roots of the sugar-cane, the sweet-potato, the pineapple and the banana plants are listed in Table 2, 3, 4 and 5, respectively.Of 69 sugar-cane fields surveyed, 86 percent or more appeared to be infested with stunt nematodes. Tylenchorhynchus martini and a species of Tylenchorhynchus (T.sp.(Ryukyu-A)), which bears clavate tail tip and no transverse striation on lip region, are widely dtsributed in Okinawa region. T. nudus was found in Ishigakijima and another stunt nematode (T. sp. (Ryukyu-B)) was obtained in Idjima near Okinawa-honto. Helicotylenchus, Pratylenchus, Meloidogyne and Hoplolaimus were found in 81, 58, 55 and 22 percent of the sugar-cane fields surveyed, respectively. Pratylenchus coffeae, P. zeae and Helicotylenchus dihystera are common in this region and P. brachyurus was found in Minami'daitojima.Helicotylenchus and Tylenchorhynchus were the most frequently encountered genera in the sweet-potato fields in Okinawa. Meloidogyne, Pratylenchus and Rotylenchulus were found, too. Some nematodes isolated from sweet-potato soils were identified as Pratylenchus coffeae and Tylenchorhynchus sp. (Ryukyu-A).Meloidogyne, Tylenchorhynchus, Pratylenchus and Helicotylenchus found were major nematodes in the soy-bean fields. Meloidogyne, Tylenchorhynchus, Helicotylenchus and Pratylenchus were extracted from tobacco soils. Besides root-knot namatodes, Helicotylenchus, Pratylenchus, Tylenchorhynchus, Rotylenchulus and Paratylenchus occurred in some vegetable fields. Helicotylenchus is the most common genus in the pineapple fields. Pratylenchus zeae was isolated from soils around roots of the pineapple plant and from uncultivated one nearby. From almost all banana soils surveyed, Helicotylenchus and Tylenchorhynchus, including T. nudus and T. sp. (Ryukyu-A), were found. Pratylenchus coffeae was isolated from banana soils in several times. Meloidogyne appeared to infect this plant, too. Tylenchulus, Helicotylenchus, Paratylenchus, Tylenchorhynchus and Criconemoides were obtained from soils around citrus roots; Meloidogyne, Helicotylenchus and Aphelenchus, were from those around papaya roots; Meloidogyne, Paratylenchus, Hernicriconemoides, and Helicotylenchus, were from those around tea roots. In Ishigakijima, Pratylenchus coffeae was found from bamboo soil. The white-tips of rice-plants caused by Aphelenchoides were seen in Okinawa-hontô and specimens of the genus Hirschmanniella were ascertained from roots of the paddy-rice.