White Clover Yield and Persistence As Influenced by Cypermethrin, Benomyl, and Root-Knot Nematode

White clover (Trifolium repens L.) stands commonly decline within 2 to 3 yr after establishment, due to insects, fungi, nematodes, viruses, and other factors. This study determined the effect of application of insecticide and fungicide, and infestation of southern root-knot nematode, Meloidogyne incognita (Kofoid & White) Chitwood, alone and in all combinations, on white clover persistence, yield, and crude protein (CP) concentration. The insecticide was cypermethrin [(±)-α-cyano-3-phenoxy benzyl (±)-cis,trans- 3-(2,2- dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate] and the fungicide was benomyl [methyl l-(butylcarbamoyl)-2-benzimidazole-carbamate]. ‘Regal’ white clover was grown on a Marietta fine sandy loam (fine-loamy, siliceous, thermic Fluvaquentic Eutrochrept) for 3 yr after establishment in 1986. No effects of the treatments on yield, stand, or CP were observed in 1987. In 1988 and 1989, yields were 52 to 85% greater in cypermethrin-treated plots, 12% greater (1988 only) in benomyl-treated plots, and 6 to 17% lower in M. incognita-infested plots compared with untreated plots. The number of stolons per meter was 27 to 39% greater in cypermethrin-treated plots, 20% greater (1988 only) in benomyl-treated plots, and 12 to 20% lower in M. incognita-infested plots, compared with untreated plots. All treatments had little effect on CP concentration. Fewer Sitona hispidulus Fab-larvae were found in the cypermethrin-treated than untreated plots in 1989. White clover decline in the field was not due to any synergistic interactions between the factors evaluated in this study. When stresses such as insect, fungi, nematode, or virus are present and limit white clover growth, selection for resistance to these stresses should contribute to improved stand longevity and production of white clover. Contribution of the USDA-ARS in cooperation with the Mississippi Agric. and Forestry Exp. Stn. Journal Article no. 7565 of the Mississippi Agric. and For. Exp. Stn.