DIFFERENTIAL SUMMER SURVIVAL OF WHITE CLOVER STOLONS - GERMPLASM AND FUNGICIDE EFFECTS

White clover (Trifolium repens L.) stands in the southeastern USA survive during summer drought predominantly through persistence of stolons. The decay and death of stolons during the hot, humid summer may be partially due to fungal diseases. This study determined the effect of summer fungicide applications on stolen survival of 'Regal' and 'Louisiana S-1' white clover compared with drought-tolerant Brown Loam Syn. No. 2 germplasm (BLSyn). The three white clover entries were grown in the held on a Catalpa silty clay (fine, montmorillonitic, thermic Fluvaquentic Hapludoll) at Mississippi State, MS, in three separate l-yr studies. During summer stolen dormancy, plots of each entry were either untreated or sprayed biweekly with benomyl [methyl 1-(butylcarbamoyl)-2-benzimidazole-carbamate]. In 2 of 3 yr, BLSyn had 23 to 63% greater ground cover, 33 to 55% greater stolen density, and 30 to 47% greater relative live stolen length following the summer drought than Louisiana S-l. In all 3 yr, BLSyn had greater relative live stolen length (7-18%) following the summer drought than Regal. Plots treated with benomyl had 14 to 52% greater stolen density (in 2 of 3 yr), 14 to 40% greater stolen growing point density, and 9 to 27% greater relative live stolen length than untreated plots. Benomyl treatment gave less of an increase in relative Live stolen length of BLSyn than in the two cultivars. These results suggest that fungal pathogenesis may reduce white clover stolen survival during summer dormancy, and that greater fungal disease resistance could be part of the mechanism of improved summer survival in BLSyn white clover.