Yield losses caused by plant parasitic nematodes graphical estimation.

Curves for graphical estimation of yield losses caused by plant parasitic nematodes were calculated on the basis of the relationship between soil nematode population density and damage to plants as described by the Seinhort's equation y = m + (1 - m) z^(P-T). By a logarithmic transformation this equation was transformed as y = m + (1 - m) 1.05^[(P/-T) + 1] and solved considering values of tolerance limit (T) and the minimum relative yield (m) from the literature. The obtained curves that can be defined "Curves of nematode-pathogenicity" allow a quick and easy evaluation of yield losses for each known crop-nematode relationship.