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 was adjusted to approximately 45 cm above the plant canopy such that the 

 swath width was equal to 3.0 m. Treatments consisted of simultaneous 

 applications of combinations of gibberellic acid (Asgrow Florida 

 Company, EPA Accession No. 08728) and 2,4-D (Union Carbide Corporation 

 EPA Registration No. 264-2AA) at the following rates: 0.0, 23.5, 47.0, 

 and 94.0 g/ha gibberellic acid and 0.56, 1.12, and 2.24 kg/ha 2,4-D. An 

 additional 2,4-D treatment at a rate 4.48 kg/ha was made due to the 

 higher biomass present in the field plots compared to the small plot 

 evaluations discussed in Part 1 of this study. 



In phase two, three 0.40 ha-plots were treated by an airboat which 

 contained a tank mix spray system calibrated to deliver 934 1/ha through 

 a hand-held spray gun equipped with a Delavan Type DFA Dela-foam nozzle. 

 The application was made by a spray crew employed by the U.S. Army Corps 

 of Engineers, Jacksonville District. The crew was instructed to treat 

 each plot in the same manner in which they conduct routine control 

 operations. Treatments consisted of 0.84 kg/ha 2,4-D; 0.84 kg/ha 2,4-D 

 plus 94.0 g/ha gibberellic acid; and 2.24 kg/ha 2,4-D. These rates of 

 2,4-D and gibberellic acid were chosen based on results of the small 

 plot evaluations (Part 1) and results of phase one, above. 



All treatments were examined weekly for evidence of treatment 

 effects. At the conclusion of 24 days of phase one, the plants in the 

 plots treated with 2.24 kg/ha and 4.48 kg/ha 2,4-D appeared to exhibit 

 100 percent control, and the decision was made to complete the efficacy 

 evaluation on day 25. Phase one efficacy evaluations consisted of har- 

 vesting the plants in three random 0.33 sq m samples from each treatment 

 plot, counting the number of viable plants, removing obvious necrotic 



