42 

 roots prior to weighing. Initial fresh weights were obtained on a 

 Mettler balance and recorded to the nearest 0.0 g. During the first five 

 series of treatment replications, 45 individual plants were sampled for 

 determination of the percent dry weight which was used for calculation 

 of initial dry weights. The percent dry weight was consistent (4.72 

 percent) and always within reported values (Penfound and Earle, 1948; 

 Bock, 1966; Westlake, 1963; Knipling et al . , 1970). 



Treatments were conducted in a completely randomized block design. 

 Treatments consisted of the simultaneous application of various com- 

 binations of gibberellic acid (GA,, Eastman Co.) and 2,4-D (Union Carbide 

 Corporation) at the following rates 0.0, 23.5, 47.0, 94.0, and 188 g/ha 

 GA 3 and 0.0, 0.28, 0.56, and 1.12 kg/ha 2,4-D. During each 

 series of treatments, an additional treatment was made at a rate of 2.24 

 kg/ha 2,4-D to simulate routine operational field application rates. 

 Each treatment rate was replicated three times per treatment series and 

 all treatment series were replicated at least twice as separate trials 

 (blocks). One additional treatment series in which the 2,4-D con- 

 centration was held constant and GAo concentration was varied between 0.0 

 to 188 g/ha was also included in the analysis. Treatment volumes 

 were approximately 934 1/ha. All applications were made with a hand- 

 held sprayer from a height of 30 cm. 



Each treatment series was observed at least twice weekly for evidence 

 of treatment effects and to adjust the water level in the barrels. 

 Plants were harvested after 14 to 17 days. Efficacy evaluations con- 

 sisted of counting the number of viable plants as determined by the 

 presence of a living rneristem (Seale and Allison, 1946), removing necrotic 



