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about plant disease incidence, sevi spatial pattern assessment system. Plant Disease 70:954-957. and spatial pattern with a system that is efficient and achieves levels of accuracy A computer software system titled Field Runner was developed to facilitate the assessment of plant not practically possible with conventional disease incidence, severity, and spatial pattern in fields. Field Runner used the stratified random sampling systems. sampling design to provide an unbiased sample and a lower percent error of the disease incidence Sampling strategy. Previously used estimates than previously used sampling designs (diagonal, "X," or "W"). The computer directed sampling techniques included "W, "X the operator to each sample site, stored the data, and provided an immediate analysis. Analyses and diagonal designs across a portion or included 1) the estimated mean and variance of disease incidence, 2) the variance-to-mean ratio, 3) all of the field (2,13) (Fig. 1 AD). an estimate of the k parameter of the negative binomial distribution, 4) an estimate of Lloyd's Usually, plants were evaluated at ran indices of mean crowding and mean patchiness, and 5) the Z-score from an ordinary runs analysis. Usuallysplants were evaluatednat a Fields could be assessed for severity of one disease or for incidence of one to several diseases intervals along these paths. Lin et al (13) simultaneously. Lettuce and alfalfa fields were sampled to test the performance of Field Runner and Basu et al (2) compared the relative under actual conditions. The incidences and aggregation indices for anthracnose and drop of accuracies of these sampling designs and lettuce and severity of alfalfa plant damage caused by alkali soil are reported. Lettuce anthracnose determined that partial-field samples and alfalfa plant damage were aggregated in foci; lettuce drop occurred randomly in the field.