Inoculation experiments were done to determine if Bursaphelenchus xylophilus could inhabit soil and infect Pinus thunbergii and P. densiflora seedlings by entry through roots. B. xylophilus was inoculated into the soil adjacent to a artificially induced wound in the taproot just below the soil surface. This procedure resulted in 100% mortality of pot grown seedlings, however, there was no mortality when the nematodes were inoculated into soil adjacent to unwounded taproots. Nematode inoculation to the soil at a distance 1cm from the seedlings did not induce disease in either wounded or unwounded seedlings. Low numbers of B. xylophilus were extracted from the soil around the roots of the diseased seedlings even though a large numbers of B. xylophilus inhabited the roots. When B. xylophilus was added to soil, nematodes could not be recovered after 72 hours indicating that B. xylophilus could not survive for an extened time in soil. These results suggest that the transmission of pine wilt disease through contaminated soil is negligible. Jpn. J. Nematol. 18: 1-5 (1989).

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The pine wood nematode, Bursaphelenchus xylophilus, is the causal agent of pine wilt disease of Japanese black pine, Pinus thunbergii and Japanese red pine, P. densiflora. The number of nematodes successfully carried by adult of the Japanese pine sawyer, Monochamus alternatus, from dead pine trees and the temporal pattern of nematode transmission to the pine twigs were examined. All adult beetles of Nara population carried nematodes when they emerged from the tree in which they developed; 94.7% for Mie population. Mean numbers of nematodes carried by a beetle of the Nara and Mie population were 1, 300 and 1, 203, respectively. Transmission pattern of nematodes from adult beetle to pine twigs in Nara and Mie had a peak transmission two and five weeks after adult emergence, respectively. The main factors affecting the number of nematodes transmitted were the number of nematodes carried by adult beetles and the longevity of the pine sawyer beetle. Jpn. J. Nematol. 18: 6-14 (1989).

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Control measures against the so-called “dieback” disease (pronounced discolouration of leaves) caused by Aphelenchoides fragariae were investigated. Based on preliminary dipping tests of nematode-infested leaves, methomyl (45%W.), trichlorfon (50%E.), and fenitrothion (50%E.) were selected among eight chemicals tested, for use for the dipping treatment of the nematode-infested bulbs, and the highest practical control efficacy was obtained by dipping the infested bulbs for about 30 minutes in 1/500 or 1/1, 000 solution of methomyl. No control was obtained by foliar sprays of methomyl at dilutions of 1/1, 000 performed at every 10 day intervals during the growing season. Hot water treatment of the nematode-infested bulbs at 45°C for 20-30 min. was also effective.

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Two treatments applied before planting and after harvest were found to be highly effective against the potato-rot nematode attaking garlic. The first treatment consisted of seed-dressing prior to planting using thiram-benomyl wettable powder at a dose of one percent (w/w) of seed. The garlic plants treated grew normally in the same way as that of the uninfested plants and no rotting occurred throughout the long period of growing season. The other treatment consisted of drying of harvested bulbs of garlic infested with the potato-rot nematode in the fields. The bulbs were dried in a heating storage room at 34-36°C for 12-17 days. The number of nematodes in the bulbs markedly decreased after the treatment. It was assumed that drastic desiccation of basal plates and membranous covers of garlic bulbs by heat drying did not allow the nematode to survive.

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Survival in liquid nitrogen was investigated for the infective juveniles of entomogenous nematodes Steinernema feltiae and S. glaseri, dauer juveniles of free-living nematode Caenorhabditis elegans, and adults of mycophagous nematode Aphelenchus avenae. When the frozen nematodes were quickly thawed at 35°C, the survival rate was over 90% for S. feltiae, 50% for A. avenae, 30% for C. elegans and less than 1% for S. glaseri. Glycerol was a more effective freeze protectant than dimethyl sulfoxide, however, the latter effectively protected nematodes frozen at -80°C. Irrespective of freeze protectants used, survival was always poor for the nematodes thawed slowly at room-temperature. Jpn. J. Nematol. 18: 30-35 (1989).

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The effect of culture filtrates of Rhizoctonia solani and Sclerotium rolfsii on the mortality of juvenile of Meloidogyne javanica and larval hatch was studied. Culture iltrates of these fungi demonstrated toxic effect to kill the second stage juveniles and inhibit the larval hatch to a varying degree. Jpn. J. Nematol. 18: 36-38(1989).

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Radopholus sanoin. sp. is described from Kyushu district of Japan. This species differs from the following known species with characteristically shortened posterior ovary: from Radopholus triversus by annulated tail tip, four lateral incisures; from R. litoralis by longer spear (16.5-19.8μm) and shape of head (elevated, dome-shaped); from R. laevis by size and thickness of spear, shape of head (not flattened anteriorly), annulated tail terminus and long hyaline part of tail. The nematode is associated with Miscanthus sinensis and/or Sasa sp. Jpn. J. Nematol. 18: 39-44 (1989).

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Tomato (Lycopersicon esculentum) seedlings with five leaves were inoculated with Meloidogyne incognita J2 at various inoculum levels one week after transplanting to clay pots (20cm diam.) containing different soil types (Andosol 1, Andosol 2, Red-yellow soil and Gray lowland soil). Weekly shoot growth of the seedlings and fresh weights of the above ground parts and roots after 40-day culture under outdoor conditions were measured. Chemical properties of the soils used were determined. Weekly shoot growth of tomato was more readily affected by nematode infection in the Andosols 1, 2 and Red-yellow soil than in the Gray lowland soil. Average fresh weights of the above ground parts in the nematode-free plot (six replications) were 196g, 203g, 218g and 246g for the Andosol 1, Gray lowlang soil, Red-yellow soil and Andosol 2, respectively (no significant difference) and these weights decreased with the increase in inoculum levels except for the low inoculum plots in the Red-yellow soil, in which growth stimulation by nematode infection was observed. Tolerance limits in the weight of the above ground parts (J2 number/ml soil) were 0.05, 0.1, 1.0 and 2.0 for the Andosol 1, Andosol 2, Gray lowland soil and Red-yellow soil, respectively. Fresh root weights increased with the increase in the inoculum levels in all the soils. Gall indices of tomato roots were not different among the soil types but the degree of occurrence of brownish and necrotic symptoms on roots was greater in the Gray lowland soil regardless of inoculum levels.

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