24 

 COCKLEBUR 



BOTANICAL 



A recent classification of the cocklebur genus, Xanthium, places 

 all of the common broadleaf forms under the one species X. stru- 

 marium, but some botanists still recognize numerous species. 

 These coarse annuals grow in a wide variety of sites including 

 fields, roadsides, and different types of waste places, but they be- 

 come especially abundant on exposed floodplains of impoundments 

 subject to drawdown. The prickly burs bear two seeds. 



IMPORTANCE 



Rank growths of the plants on flood plains and impoundment 

 margins often occupy space that would support duck-food plants. 

 Also seedlings in the cotyledon stage are reported toxic to live- 

 stock. In their favor is the fact that seeds of cockleburs are eaten 

 tc a limited extent by mourning doves. 



CONTROL 



Cockleburs can be killed readily by herbicides. Formulations 

 of 2,4-D are effective at the rate of 1/2 pound acid equivalent per 

 acre. Recent tests at the Tennessee National Waterfowl Refuge 

 have indicated that silvex gives satisfactory results at 14 pound 

 per acre. Also, complete flooding for 12 to 15 days has been 

 found to kill cockleburs. 



