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

White clover (Trifolium repens L.) stands in the southeastern USA surv ive during summer drought predominantly through persistence of stolons . The decay and death of stolons during the hot, humid summer may be p artially due to fungal diseases. This study determined the effect of s ummer fungicide applications on stolen survival of 'Regal' and 'Louisi ana S-1' white clover compared with drought-tolerant Brown Loam Syn. N o. 2 germplasm (BLSyn). The three white clover entries were grown in t he held on a Catalpa silty clay (fine, montmorillonitic, thermic Fluva quentic Hapludoll) at Mississippi State, MS, in three separate l-yr st udies. 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 Louisian a S-l. In all 3 yr, BLSyn had greater relative live stolen length (7-1 8%) following the summer drought than Regal. Plots treated with benomy l had 14 to 52% greater stolen density (in 2 of 3 yr), 14 to 40% great er stolen growing point density, and 9 to 27% greater relative live st olen length than untreated plots. Benomyl treatment gave less of an in crease in relative Live stolen length of BLSyn than in the two cultiva rs. These results suggest that fungal pathogenesis may reduce white cl over stolen survival during summer dormancy, and that greater fungal d isease resistance could be part of the mechanism of improved summer su rvival in BLSyn white clover.