Nonrandom Patterns of Bacterial Brown Spot in Snap Bean Row Segments

Graphs of the proportion of diseased leaflets per plant (disease incidence values) versus plant position along the row suggested two types of nonrandom variability in disease: an extreme jaggedness superimposed on a slow, undulating change in disease. Arcsine square root-transformed disease incidence values were analyzed for spatial nonrandomness using three techniques: runs analysis, autocorrelation analysis, and autoregressive integrated moving average (ARIMA) modeling. All three techniques detected the slow, undulating change in disease incidence values; however, only ARIMA modeling detected the jaggedness and could quantify both patterns