Seasonal variation in the horizontal spatial pattern CF the root-knot nematode, Meloidogyne incognita and application of the negative binomial and taylor's power law models in developing sampling schemes

The horizontal spatial pattern of Meloidogyne incognita in an brinjal field was highly aggregated and could usually be described by the negative binomial distribution model. The spatial pattern was affected by the growth and cultural practices. It tended to become more random as the crop matured but reverted back to scattered patches following post-harvest ploughing in summer. The parameters of the negative binomial as well as of the Taylor's power law models were not solely species specific but also varied with the increase in sampled area and the season. The mean population density and the degree of aggregation determined the desired sampling intensity for precise estimates. The least number of cores was required about a fortnight before the final harvest. Sampling after dividing the field into a grid could give more precise estimates of the mean population density than the random sampling of the entire field.