Sclerotinia trifoliorum Erikss. on white clover ( Trifolium repens L.)

Herbage dry‐matter yields of sown plots of white clover were greatly reduced by a natural infection of clover rot ( Sclerotinia trifoliorum ), the extent of the reduction being related to the level of infection. Examination of seasonal yield patterns suggested that although the plants apparently recovered from the disease it re‐exerted its influence later in the season. No effects on seed yield could be detected but effects on the development of inflorescences and the proportion of ripe heads surviving to harvest were noted. Marked differences between varietal types existed for some of the characters examined.