28 HIBISCUS 



and have attractive flowers, but there is little else to recommend 

 them. Their seeds are seldom eaten by ducks or other v^^ildlife, 

 and locally the plants are serious weeds in waterfowl and muskrat 

 habitat. 



CONTROL 

 Experiments on eradication of this weed in Delaware and Mary- 

 land have shown that effective control can be obtained by mod- 

 erately light dosages of 2,4-D, by underwater cutting, or by 

 drowning. Valuable duck-food plants have become established in 

 test plots where hibiscus was eliminated. Reinfestation should 

 be prevented by avoiding, if possible, continuous drawdown dur- 

 ing the growing season. Where protracted lowering of levels is 

 unavoidable, temporary reflooding of the area will drown the 

 seedlings. 



HERSrCIDES 



Tests on H. moscheutos have indicated that 2,4-D (about 6 1/2 

 pounds per acre, 0.5% concentration, and 160 gallons per acre) 

 gives about 95% control if applied during full-flowering or early- 

 fruiting stages. Also, treatments with a mixture of 2,4-D at 

 4 pounds and TCA at 50 pounds per acre have given consistently 

 good control. Results have been nearly the same on H. militaris. 



DROWNING 



Mature plants of H. militaris and H. lasiocarpos at Isom Lake, 

 Tenn., were drowned by a permanent 3-foot rise in water level. 

 Similar results have been obtained in TVA impoundments. In 

 the Thousand-Acre Marsh near Delaware City, Del., H. moscheutos 

 was nearly eliminated by an increase in water level varying from 

 15 to 30 inches and lasting about a year. 



Seedlings can be controlled readily by drowning. In Delaware 

 it was found that hibiscus seedlings can be drowned without de- 

 stroying seedlings of desirable species such as smartweeds and 

 Walters wild millet. 



cuniNG 



Small-scale tests on cutting of hibiscus by sickles in Delaware 

 and Maryland have shown that if the cut bases are submerged 

 continuously, one mowing can give a high degree of control. In 

 other situations, two cuttings may eliminate 95% or more of the 

 plants. The two cuttings may be timed 1 to II/2 months apart, 

 or the second cutting may even occur in the following year and 

 still be nearly equally effective. 



REFERENCE 

 1954. The Marshes of Delaware, Their Improvement and Preservation (p. 35). 

 John H. Steenis and Others, Delaware Board of Game and Fish Comm. 



