Size and Shape of Plots for Estimating Yield Losses from Cereal Foliage Diseases

Abstract

Data from uniformity trials on healthy and diseased wheat and oat crops showed that the coefficient of variation for yield decreased as plot size increased and became nearer to square in shape. Infection with Septoria leaf blotch of oats and powdery mildew of wheat did not appear to affect yield variability. Plots larger than rod row size (where 16 ft of the centre row of 3 rows is harvested) are recommended to detect differences of 1 o per cent in yield between two treatments.

Epidemic spreading in random rectangular networks

“…The immediate consequence of this lack of mobility is the fact that the shape of the plot or field in which the plants are distributed may significantly affect disease dynamics. In fact, there is both empirical and theoretical evidence that supports this hypothesis [22][23][24][25][26][27][28][29][30]. In general, it has been suggested that square plots and fields favored higher spreading of plant diseases than elongated ones of the same area [22][23][24][25].…”

“…In those cases, the size and shape of the plots is controlled typically to estimate crop yields. Thus, they are typically of almost perfect square or rectangular shapes (see for instance [24]). The second scenario is when crops are cultivated in country fields.…”

“…In fact, there is both empirical and theoretical evidence that supports this hypothesis [22][23][24][25][26][27][28][29][30]. In general, it has been suggested that square plots and fields favored higher spreading of plant diseases than elongated ones of the same area [22][23][24][25]. We should make here some remarks about the shape of plots in different scenarios.…”

Measuring and Modeling Crop Losses at the Field Level

“…If this is not possible, (16)(17)(18)(19)(20)(21)(22) has made especially important contributions to the science of crop loss assessment. In an elegant and pioneering series of papers in the 1970s, James and co-workers (16)(17)(18)(19)(20)(21)(22) showed that crop loss assessment and modeling are, indeed, of scientific merit. Methods for measuring and quantifying disease intensity in single plants and fields (23,24,42) and for determining and predicting crop losses are improving.…”

“…Preliminary (16). First, the experiments should be conducted in more than one experiments should be conducted to determine sample sizes needed location, and preferably in areas where the crop is normally grown to produce results with a certain level of precision (19). Often there and the disease is important.…”