Reproduction of four populations of Meloidogyne incognita on ten oat varieties was examined in a greenhouse. Eggmass numbers produced on oat roots inoculated with 500 J2 were counted. Eggmasses of all nematode populations were present on all oat varieties but“Tachiibuki”had the lowest number (1.8 - 11.8 eggmasses / root system). Summersown cultivation of four early forage oat varieties sown in September and a fallow treatment were examined in a field infested with M. incognita and M. arenaria. The final / initial population density of J2 (Pf / Pi) in December for varieties “Haeibuki”,“Super Hayate Hayabusa”, “Tachiakane”,“Tachiibuki”and the fallow were 36.5, 34.7, 23.9, 1.9 and 0.2, respectively. Yield of succeeding sweet potato planted in May of the next year and harvested in September was highest in the plot that was previously cropped with the variety “Tachiibuki”, and in the “Tachiakane” plot which also received a nematicide treatment (1.5% a.i. fosthiazate, 20 kg / 10 a) before planting. Sweet potato storage roots from the “Haeibuki”, “Super Hayate Hayabusa” and fallow plots were significantly damaged by root-knot nematode with similar low yields. Damage to storage roots caused by the nematode was significantly reduced by the preceding “Tachiibuki” cropping to an extent similar to the nematicide treatment.

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Verticillium lecanii is a potentially useful biological control agent (BCA) for soybean cyst nematode (SCN), Heterodera glycines. The objective of this study was to screen hybrid strains of V. lecanii, derived from protoplast fusion, for effective control agents of SCN, and to investigate whether the protoplast fusion technique is an effective tool for development of nematode control agents. Three parental strains (Vertalec®, Mycotal®, and B-2) and their 162 hybrid strains were screened in greenhouse pot tests. Some of these hybrid strains suppressed damage on soybean plants and reduced the density of SCN in the soil. In particular, one hybrid strain, AaF42, was observed to reduce the nematode egg density by 93.2% as compared with the control. Furthermore, this strain significantly reduced the cyst and egg density as compared with the parental strains. In conclusion, some of the hybrid strains exhibited enhanced biocontrol efficacy by protoplast fusion. Therefore, the protoplast fusion technique may be a potentially valuable tool for developing nematode-antagonistic fungi as BCA.

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The relationship between damage to burdock caused by Pratylenchus penetrans after rotary harrow cultivation (20-30 cm depth) and trencher cultivation (1 m depth) was studied. In the past, burdock fields were rotary cultivated prior to planting and these fields were associated with severe P. penetrans damage symptoms of brown or black spots on the root that fused to form black mottles (common name, “Black Symptom”). Currently, rotary cultivation is followed by trencher cultivation before planting which mixes topsoil having the highest P. penetrans densities with deeper soil having much lower nematode densities. Trencher cultivation is associated with less P. penetrans damage than rotary cultivation and has symptoms of small brown spots on the root (common name, “Sesame Symptom”) thought to be due to reduced nematode densities that result from mixing high nematode density soil with low density soil. The relationship between P. penetrans density and burdock damage was examined in trencher cultivation. All roots that had a rootlesion index and root-deformity index of 2 or less (0 to 4, 0 = 0%, 4 = 100% damage) were considered to be marketable burdock roots. The nematode density of the tolerable injury level threshold was defined as the nematode density that corresponded to 80% of the burdock roots being marketable. The tolerable injury level threshold was based on the number of nematodes extracted by the Baermann funnel technique from 25 g of wet surface soil (0-20 cm depth) for 48 hrs. This value was 6.1 P. penetrans / 25 g soil before trencher plowing, and 3.2 P. penetrans / 25 g soil after trencher plowing.

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Reproduction of Pratylenchus coffeae on 25 sweet potato cultivars was examined in greenhouse and field plot tests. In the greenhouse test P. coffeae reproduced on 21 cultivars with Pf/Pi values of 1.2-26.9. In the field plot test all cultivars had final population densities higher than the initial densities. The P. coffeae reproduction rate on each cultivar had little correspondence with the level of resistance determined in a breeding procedure based on storage root damage. Of all cultivars tested, Elegant Summer showed the lowest reproduction rate in both tests.

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[in Japanese]

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[in Japanese]

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Erratum to“A new distribution record of Steinernema abbasi Elawad, Ahmad and Reid, 1997 (Rhabditida: Steinernematidae) in Japan with a note on its pathogenicity against the turnip moth larvae, Agrotis segetum (Lepidoptera: Noctuidae)”
Jpn. J. Nematol. 37 (2), 51-60 (2007)

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