Transfer of biological soil suppressiveness against Heterodera schachtii

Heterodera schachtii-suppressive soil at a rate of either 1 or 10% (dry wt/ wt) transferred suppressiveness against the beet cyst nematode to fumigated field plots when mixed into the upper 10-cm soil layer. Soil suppressivene ss was established after 1 month of moist fallow and 77 days of Swiss chard cropping in the 10% transfer treatment and after 230 days in the 1% transf er treatment. The number of infective second-stage juveniles (52) of H. sch achtii, monitored initially at 150 degree-day intervals and later at 300 de gree-day intervals, indicated the status of suppressiveness in the differen t treatments during the cropping period. In a greenhouse experiment, amendi ng fumigated field soil with 0.1, 1.0, or 10% suppressive soil, suppressed multiplication of H. schachtii when soils were infested with an additional 5,000 J2. In a second greenhouse experiment, a fumigated sandy loam amended with 10 or 25% suppressive soil and a fumigated loam amended with 25% supp ressive soil had significantly fewer eggs per cyst than the nonamended fumi gated treatments when 1,000 52 were added.