Size of Maize Sample Needed to Determine Percent Kernel Infection by Aspergillus flavus . Gene E. Scott, USDA-ARS and Mississippi Agricultural and Forestry Experiment Station, Mississippi State 39762. Natale Zummo, USDA-ARS and Mississippi Agricultural and Forestry Experiment Station, Mississippi State 39762. Plant Dis. 79:861-864. Accepted for publication 18 April 1995. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1995. DOI: 10.1094/PD-79-0861.

Aspergillus flavus usually infects a low percentage of maize kernels, but it is a very important pathogen because it produces aflatoxin. The object of this study was to determine the needed kernel sample size per plot in replicated trials to ascertain the percentage of infection by A. flavus at a reasonable level of precision. We compared 65-, 130-, 195-, and 390-kernel sample sizes. Two experiments were simulated to determine which statistical attribute(s) was the most sensitive to changes in sample size. The changes in error mean squares and F values between 65- and 390-kernel samples were of a magnitude greater than six, which was larger than for the other statistical attributes. Based on averages of error mean squares, F values, and Spearman correlation coefficients over eight experiments with actual data, we concluded that a 390-kernel sample size is not too large, and a sample size of approximately 200 kernels should be considered a minimum. Based on other calculations, a minimum sample size of 100 kernels is needed just to have a reasonable probability of detecting the fungus when it is present.