Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 1, 1998
Publication Date: N/A
Interpretive Summary: White clover may be difficult to establish by sod seeding into a grass sod. Insects, slugs, and snails often damage or kill white clover seedlings after germination. Some white clover plants are cyanogenic which means they contain chemicals that are released as hydrocyanic acid when the leaves are damaged. Insects, slugs, and snails prefer to feed on plants that do not release this acid. The objective of this study was to determine if these cyanogenic white clover plants would have less insect damage and greater seedling survival when seeded in a grass sod. We found that the cyanogenic white clover improved seedling survival in a bermudagrass sod and had less insect feeding damage compared to white clover that wasn't cyanogenic. Most white clover cultivars grown in the U.S. are not cyanogenic. The incorporation of cyanogenesis into U.S. cultivars could improve white clover seedling establishment in grass sods.
Technical Abstract: Cyanogenesis in white clover, Trifolium repens L., has been shown to confer resistance to a number of leaf-feeding insects and molluscs, but most cultivars grown in the U.S., however, are acyanogenic. White clover seedlings may be damaged or completely killed by insect feeding during establishment into a grass sod. The objective of this study was to determine if white clover stand establishment in a grass sod was influenced by cyanogenesis. Two cyanogenic white clover populations, HCNpi and BLHplus, and two acyanogenic populations, `Regal' and BLHminus, were sod seeded into common bermudagrass [Cynodon dactylon (L.) Pers.] at two locations in 1994 and one location in 1995. The studies were conducted in a RCBD with four replications at Mississippi State, MS. Cotyledons, unifoliate leaves, and trifoliate leaves were rated for insect damage and leaf area lost due to insect feeding at 2, 4, and 6 wk after seeding. No differences were noted between the populations for seedling survival at 2 wk after seeding. At 4 and 6 wk after seeding, the highly cyanogenic population, HCNpi, had fewer plants with trifoliate leaves damaged and less leaf area lost due to insect feeding than either acyanogenic population. HCNpi had 88% seedling survival at 6 wk compared to only 66% for acyanogenic Regal. Cyanogenesis in white clover improved seeding survival in bermudagrass sod. The incorporation of limited levels of cyanogenesis into acyanogenic U.S. cultivars could improve seedling establishment without the animal toxicity concerns of highly cyanogenic types.