Abstract
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.
