IT has been known for many years1 that close spacing of groundnuts, Arachis hypogaea L., reduces the incidence of groundnut rosette in a crop. Storey and Ryland2 pointed out that there was a reduction in the number of rosette virus-infected plants per unit area of land, as well as the reduction in percentage infection that would be expected with larger plant populations associated with close spacing3. Analyses of experiments on groundnut spacing4 have confirmed this result, but in a few experiments there were no significant differences in the numbers of infected plants per unit area at harvest5,6.