MODELS:

A number of models to help predict damage resulting from nematode infestation have been developed. The "Seinhorst Model" is an example of this effort and the basis for many subsequent models that have been developed.

Nematode management in annual crops can be based on the fact that there is typically an inverse relationship between the numbers of nematodes and crop yield. A critical-point, quantitative functional relationship between nematode population density at planting and relative crop yield was established for annual crops by Seinhorst (1965) as:

where

• Y = crop loss
• M = the minimum relative yield in the presence of high nematode densities,
• T = the initial nematode density at which relative yield is reduced, or the tolerance limit,
• Z = a term for the per capita damage to plant roots, considered the proportion of the root system that remains undamaged by a single nematode; typically a value slightly less than one,
• P = the initial (preplanting) nematode density (also, Pi).

Seinhorst, J. W. 1965. The relation between nematode density and damage to plants. Nematologica 11:137-154.

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