Analysis of the effects of selected agronomic factors on the dynamics of the take-all disease of wheat in field plots

Linear models were used to investigate the effects and interactions of treatments for the control of disease in multifactorial experiments on the dynamics of the take-all disease of wheat. Analyses were based on repeated measures of disease on second successive winter wheat crops in three successive seasons. The treatments were date of sowing, presence or absence of triadimenol-containing seed treatment, autumn nitrogen and chloride applications, timing of early spring nitrogen and total spring nitrogen applications. The effects of treatments were investigated on linear and quadratic trends of disease increased and on the integral amount of disease over time. Different disease variables were used to express disease relative to the total and diseased plant populations. The effects of treatments on absolute and relative numbers of diseased roots per plant were also analysed. During three seasons when disease was never severe, the effects of the treatment were shown to be variable.