Southern Anthracnose, caused by Colletotrichum trifolii, is a serious disease of red clover (Trifolium pratense) and can lead to the death of the plants. The degree of resistance is highly variable among cultivars. The objective of this study was to assess whether phenotypic selection within a cultivar improves the resistance to Southern Anthracnose. Out of each of seven cultivars with moderate to low resistance level, we selected 10 resistant genotypes. Within each cultivar, the resistant genotypes were crossed by manual pollination. The resulting F1 progeny of each cross was then evaluated in the greenhouse for resistance to C. trifolii, along with the original cultivars. Plants of the F1 progeny survived at a rate of 53 to 77 %, with a mean of 64 %. The resistance of six out of seven cultivars was significantly improved already after one cycle of selection. On average, the resistance level was increased by 28 % (with a range of 18 to 52 %) compared to the parental cultivar. The increase was highest in cultivars with a low initial resistance. The data suggest that few major genes are involved in Anthracnose resistance in the cultivars tested.
