18 ALLIGATORWEED 



It reproduces and spreads mainly vegetatively ; seeds are not 

 known to be produced in this country. Broken-off branch frag- 

 ments root readily, and stems may elongate as much as 200 inches 

 in one season. Alligatorweed grows rooted in mud but often ex- 

 tends considerable distances over water surfaces. It is tolerant 

 of flooding and, though mainly a fresh-water plant, endures mild 

 salinity. 



IMPORTANCE 



Alligatorweed is eaten some by baldpates, gadwalls, coots, musk- 

 rats, and nutrias, and to a limited extent by hogs and cattle, but it 

 has no value that compensates appreciably for its detriment It is 

 one of the worst pest plants of the Southeast, obstructing naviga- 

 tion in canals, bayous, and lakes, destroying beds of duck foods, 

 ruining fishing areas, and causing a serious malaria hazard in 

 some localities. 



CONTROL 



During the past quarter of a century, effective control of alliga- 

 torweed has remained an unsolved problem. Various methods 

 and means tried have proved costly and unsatisfactory. Recently, 

 however, certain new herbicides have given indication of useful- 

 ness for this purpose. Sterilants such as erbon have shown prom- 

 ise in unflooded sites, and several new herbicides, both alone and 

 in combinations, have given encouraging results on alligatorweed 

 in flooded places. 



Among sites or conditions in which control is especially difficult 

 are continuously flooded waterways, growths partially buried under 

 silt, and heavily matted beds. Alligatorweed on unflooded flats or 

 on dikes can be killed somewhat more readily. Because of the 

 plant's ability to reinvade rapidly, control needs to be complete or 

 nearly so. 



Crushing, cutting, and mechanical removal of beds, as was done 

 extensively in Louisiana formerly, provided expensive and only 

 temporary opening of waterways that were clogged by alligator- 

 weed. Though subsequent use of 2,4-D for this purpose reduced 

 operational costs, it too contributed comparatively little toward 

 extermination or enduring control of the plant in extensive areas. 

 The cooperative study conducted from 1948 to 1950 by the Boyce 

 Thompson Institute, the Corps of Engineers, and Tulane Univer- 

 sity reported that 2,4-D (preferably the amine salt) applied at 8 

 pounds per acre during the season of less active growth, from July 

 tc the following spring, gave nearly complete control of beds extend- 

 ing over water in experimental pools. However, general experi- 

 ence elsewhere with 2,4-D treatment has been discouraging. Usu- 

 ally, only temporary setback has resulted. 



