Sicklepod (Cassia obtusifolia) and Coffee Senna (Cassia occidentalis): Geographic Distribution, Germination, and Emergence

The distribution of sicklepod (Cassia obtusifoliaL.) and coffee senna (Cassia occidentalisL.) in the United States is similar and both species are increasing as problems within their range. Sicklepod is a problem in 11 southern states and increasing in 12 while coffee senna is a problem in 7 states and increasing in 8 states. Both species germinated over a wide range of temperature. Germination characteristics were similar in the range of 15 to 36 C. Germination of coffee senna was drastically reduced at 39 C byRhizopussp. Seedling growth was similar for both species and was maximum from 30 to 36 C. Both species have a hard seedcoat. Abrasion for 5, 10, or 15 s, puncturing with a needle, and sulfuric acid were all effective in initiating germination. Both species emerged from a soil depth of 12.5 cm; however, emergence of sicklepod was more rapid than coffee senna with 63% of the sicklepod seedlings emerging from 2.5 cm after only 3 days.