Data were arcsine transformed to stabilize variances and pairwise comparisons using t-test were used to separate the means in the analysis of variance of incidence, based on a sample of 10 plants per field, in ecozones by country. Data were arcsine transformed to stabilize variances, but results are presented as re-transformed means. Treatment and transformation of data and statistical analysis generally followed the method used by Cardwell et al. (1997).