Reduction of potato scab, Verticillium wilt, and nematodes by soymeal and meat and bone meal in two Ontario potato fields.

Soymeal (SM) and meat and bone meal (MBM) were incorporated into soil to a depth of 15 cm at a rate of 37 t/ha at two commercial potato (Solatium tuberosum) fields in Ontario in the spring of 1996. The incidence of verticillium wilt and potato scab, the population of plant parasitic nematodes, and the soil chemistry and microbiology were monitored in three subsequent crops of potatoes in 1996-1998. Verticillium dahliae microsclerotia (MS) were buried in the soil immediately after incorporation of the amendments, both in the field and in a concurrent laboratory assay using soil from the field placed in test tubes, and the viability of the MS was determined 4 weeks later. Both treatments reduced the incidence of verticillium wilt, potato scab, and the nematode population to near zero levels in 1996. Reduced disease levels were still evident in the 1997 crop, but by 1998, disease levels were equal to or higher than those in the control treatments. Nematode numbers remained below control levels for the 3 year...