Differential red clover germplasm response to defoliation and fungicide application

A primary limitation to the use of red clover (Trifolium pratense L,) in the temperate zones is poor persistence. The objective of this research was to evaluate the effects of defoliation and fungicide application on the yield and persistence responses of twelve diverse red clover germplasms. Treatments consisted of reduced defoliation with the application of the systemic fungicide, propiconazole (RDF), reduced defoliation (RD) and a full-season defoliation control. Dry-matter yields were recorded for 3 years and stand density was determined during the third harvest year and again 2 years later. By the third harvest season, stand densities were 52% and 13.5% greater for treatments RDF and RD than the control. After 5 years, stand density on these two treatments was on average 68% greater than the control. RDF plots outyielded RD plots for the second and third harvest years, but both had lower forage yields than the control. Germplasm by treatment interactions were significant for stand density and yield by the third year. RD treatments outyielded the control by the third year for only two germplasms, the experimental lines FL-MTC and FL6-EF. The treatments affected yield and persistence and enabled the identification of significant differences in germplasm response.