50 



WATERLILIES 



BOTANICAL 



The two closely related species of white-flowered waterlilies, 

 Nymphaea odorata and tuberosa, occur commonly and often abun- 

 dantly in ponds and lakes of the Eastern States. Three other 

 species have less importance as weeds because their distribution 

 i? limited. Banana waterlily, N. mexicana, is a valuable duck food 

 locally along the Gulf and South Atlantic Coasts. 



IMPORTANCE 



Waterlilies, whether growing wild or planted in ponds or for- 

 mal pools, are attractive to the eye, and their seeds have some 

 usefulness as food for ducks. As long as their beds remain 

 sparse they are not likely to be objectionable, but frequently water- 

 lilies become so dense as to shade out submerged duck-food plants 

 and interfere with fishing and boating. 



CONTROL 



At present, no method of control has proved uniformly effective 

 on waterlilies in different places. Results with herbicides, includ- 

 ing various formulations of 2,4-D, or with mowing have gener- 

 ally required repeated operations in two or more years. Excellent 

 small-plot kills have been obtained with 2,4-D isopropyl ester at 

 the rate of 2 pounds acid equivalent per acre on the Lacassine 

 Refuge in Louisiana. The treatments were made in May on mixed 

 growths of waterlilies and watershield {Brasenia schreberi) with 

 the result that nearly pure stands of watershield dominated the 

 plots. 



Experiments with new herbicides are under way at several sta- 

 tions but at this time no conclusive results are available. 



