Germination and Emergence Characteristics of Common Beggar’s-Tick (Bidens alba)

Common beggar’s-tick is an annual weed commonly found in citrus groves in Florida. A series of laboratory and greenhouse experiments were conducted to determine the germination response of common beggar’s-tick to various environmental factors that influence seed survival, germination, and dormancy. The results suggest that common beggar’stick germinated over a wide range of temperatures (15 to 40 C) and in both alternating light and dark and dark conditions. New seeds (collected in 2010) germinated better than the old seeds (collected in 2007) at 15/10 C; however, at temperatures above 35 C, the old seeds germinated better. The highest germination was 95% at 25 to 30 C with old seeds compared to 78 to 86% at 20 to 30 C with new seeds. Germination of common beggar’s-tick was inhibited at osmotic potential above 20.6 MPa and salt concentrations of 320 mM. Highest germination in common beggar’s-tick was found under neutral conditions (pH 7); germination decreased sharply under increasing acidity and alkalinity. Emergence decreased as depth of sowing increased, with greatest germination (89 to 91%) occurring when sown at the surface (0 cm) regardless of seed age. No germination was observed when seeds were buried at 10 cm. Results of this study suggest that favorable temperature and soil pH, and adequate moisture in Florida ensures the germination and continued presence of common beggar’s-tick. Nomenclature: Common beggar’s-tick, Bidens alba (L.) D.C.