Field experiments were conducted to determine the effect of green manure as fallow on common scab of potato caused by Streptomyces turgidiscabies. Significantly fewer diseased tubers were harvested from soil incorporated with lopsided oat or woolly pod vetch compared with those from oat and continuous potato cultivation in a planter experiment. Each field experiment consisted of lopsided oat cultivated during the spring and summer prior to the potato planting. Comparisons were also made with several other treatments, including cultivation of woolly pod vetch, oat, soybean, sugar beet, and potato (‘Yukirasya’, which is resistant to potato common potato scab) and soil application of Ferosand (Fe, mainly FeSO4, to decrease the soil pH). In field experiments conducted during 1999–2000, treatment with lopsided oat followed by lopsided oat or woolly pod vetch was significantly more effective at suppressing the disease severity than oat and continuous potato cultivation (P < 0.001). An increase in the marketable tuber ratio was also more significant than for oat and continuous potato cultivation (P < 0.001). In field experiments conducted during 2000–01, lopsided oat cultivation alone and with the application of Ferosand (1.8 t/ha) or resistant potato cultivar treatment were significantly more effective at suppressing the disease severity and incidence than sugar beet cultivation (P < 0.001), even under high disease intensity in the field. However, potato yield had a tendency to reduce after lopsided oat treatment with an application of Ferosand (1.8 t/ha) compared with lopsided oat alone or the application of Ferosand at 600 kg/ha, due to low pH conditions. In field experiments conducted during 2001–02, the lowest severity and incidence of common scab of potato were observed in soil treated with lopsided oat than with other treatments (P < 0.05 and P < 0.001, respectively). These findings suggest that lopsided oat used as fallow green manure can reduce the severity of common scab and increase potato yield.

. Eiiti YAMADA2, Ken HASHIZUME2, Minoru TAKAHASHI2, Mieko KITASHIMA3, Seiji MATSUI3 and Hideki YATSU3.Parasitism of Meloidogyne incognita, M. arenaria, Pratylenchus penetrans and P. coffeae was examined on five hybrid sorghum, other four gramineous plants (guineagrass, oat, sudangrass, Italian ryegrass) and crotalaria. Of all strains and plants examined, the sorghum strain SS701 named Tuchitaro was the most effective as an antagonistic green manure plant for the control of M. incognita and M. arenaria but not of P. penetrans and P. coffeae. Jpn. J. Nematol. 30 (1/2): 18-29 (2000).

No abstract

Antagonistic effect of leguminous green manure crops on Heterodera glycines and the effect of these crops on Pratylenchus penetrans. Eiiti Yamada, Ken Hashizume and Minoru Takahashi1.The infestation of Heterodera glycines (SCN) (race 1) was observed in 14 leguminous crops tested by pot. When dividing development of infested SCN in the root, percentage of females and cysts was very low (0-1.4%) in the following crops. That is five species of clover (red clover, crimson clover, persian clover, white clover and alsike clover), alfalfa, Crotalaria spectabilis, resistant soybean (Suzuhime) derived from the Peking line, Crotalaria juncea, blue lupine and wooly-pod vetch. The nematode population in the soil after the cultivation of these crops declined greatly.Field test was carried out at Mukawa SCN (race 1) infested field (120 eggs/g dry soil). The density of SCN eggs declined to about 5 eggs after three months cultivation from May 16th of red clover, crimson clover, wooly-pod vetch and resistant soybean (Suzuhime), but they increased the density of Pratylenchus penetrans. The cyst index of susceptible soybean (Suzumaru) as aftercrop of red clover, crimson clover, wooly-pod vetch and resistant soybean (Suzuhime) was lowered. Soybean yield was 130-140 kg/10 a of dry matter after crimson clover, wooly-pod vetch and resistant soybean (Suzuhime), but 80 kg/10 a at red clover, 24 kg/10 a at wild oats (Avena strigosa), 30 kg/10 a at susceptible soybean (Suzumaru). Crimson clover, wooly-pod vetch and resistant soybean (Suzuhime) were selected as antagonistic plant of SCN.

Inoculation test was conducted to confirm the influence of Pratylenchus penetrans on the infection of adzuki bean by Phialophora gregata f. sp. adzukicola, causal agent of brown stem rot of adzuki bean, in the green house. It was considered that high densities of P. penetrans enhanced the invasion of P. gregata f. sp. adzukicola to adzuki bean and the ratio of the highest brownish node to total nodes of adzuki bean. From the result, P. penetrans was clarified as one factor which enhanced the invasion of P gregata f. sp. adzukicola to adzuki bean. Jpn. J. Nematol. 35(2), 71-77 (2005). Key words: brown stem rot of adzuki bean, fungus-nematode interaction, Phialophora gregata f.sp. adzukicola, Pratylenchus penetrans.