SIZE OF MAIZE SAMPLE NEEDED TO DETERMINE PERCENT KERNEL INFECTION BY ASPERGILLUS-FLAVUS

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 p er 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 ch anges in sample size. The changes in error mean squares and F values b etween 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 co efficients over eight experiments with actual data, we concluded that a 390-kernel sample size is not too large, and a sample size of approx imately 200 kernels should be considered a minimum. Based on other cal culations, a minimum sample size of 100 kernels is needed just to have a reasonable probability of detecting the fungus when it is present.