Synergistic effect of gibberellic acid and chlorflurenol on 2,4-D with regard to water hyacinth control

Effect of gibberellic acid and 2,4-dichlorophenoxyacetic acid on waterhyacinth, Eichhornia crassipes (Mart.) Solms /

“…(1978) Results of these experiments indicated that combinations of GA and 2,4-D at 6 to 8 g/ha and 100 g/ha, respectively, caused death of the plants within one week. The same response was noted in plants which received only 1000 g/ha 2,4-D. Pieterse and Roorda (1982) reported similar results when the 2,4-D and GA were applied simultaneously in the same solution at an extremely low volume rate of 40 1/ha.…”

“…These findings are not in agreement with results reported for the effects of GA3 and 2,4-D on waterhyacinths by Pieterse et al . (1980) and Pieterse and Roorda (1982). However, differences in experimental design and environmental controls (greenhouse versus non-greenhouse, open air situations) may account for the lack of agreement.…”

“…Pieterse et al . (1980) and Pieterse and Roorda (1982) reported a tenfold increase in the activity of 2,4-D on Eichhornia crassipes when applied in combination with GA^.…”

“…Foliar application of GA 3 at a rate of 6.0 g/ha was also shown to inhibit the formation of float-type leaves although apparently not as dramatically as when GA3 was applied to the roots (Pieterse et al . , 1980;Pieterse and Roorda, 1982 (Salisbury and Ross, 1978). The existence of naturally occurring compounds which stimulated plant growth was first demonstrated by Seubert in 1925 (Weaver, 1972).…”

“…Based on results of these two studies, it was hypothesized that (1) such a large reduction in the quantity of 2,4-D might lower the costs of control programs even though costs of GA is relatively high (Pieterse et al . , 1980) and (2) a decrease in the 2,4-D concentration would lower the risk to nearby native vegetation or crops (Pieterse and Roorda, 1982).…”