Portal de Periódicos da CAPES

Application of Herbicides to Cut Stumps of a Woody Tropical Weed

1949; University of Chicago Press; Volume: 111; Issue: 2 Linguagem: Inglês

10.1086/335586

1940-1205

John G. Torrey, Kenneth V. Thimann,

Allelopathy and phytotoxic interactions

1. The effectiveness of several herbicides when applied in high concentration by painting on the cut stumps of aroma or marabu (Dichrostachys nutans) has been determined. 2. A 20% aqueous emulsion of the butyl ester of 2,4-dichlorophenoxyacetic acid (2,4-D), applied twice, was the most effective of the preparations tried in repressing new shoot growth. Higher or lower concentrations of this emulsion, the butyl ester of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), and concentrated sodium arsenite solutions were all less effective. 3. The addition of gas oil to the 2,4-D ester greatly retarded the latter's effectiveness, and there was evidence of inhibition of its transport in the stump. 4. Extraction and bio-assay of the 2,4-D in portions of treated plants showed no evidence of its entry into the roots, within 21/2 weeks, though it was detected in stems. 5. Removal of the tops of the plants causes a decrease in starch content of the roots, but over a period of several weeks the starch content may rise again, possibly as a result of contributions from other plants on the same root system. 6. Defoliation by treatment with 2,4-D also brings about great reduction in starch content, but unhindered development of leafy shoots increases it. It is suggested, therefore, that repeated defoliation may be necessary for killing the underground parts of the plant.