Skip to main content Accessibility help
×
Home

A Bioassay Technique Detects Imazethapyr Leaching and Liming-Dependent Activity

  • Leon J. Van Wyk (a1) and Carl F. Reinhardt (a1)

Abstract

Excessive persistence of imazethapyr has been responsible for injury to corn grown after soybean. Factors implicated in corn injury reported from certain parts of the main corn-producing region in South Africa were: leaching of herbicide to deep soil layers during the season of application, followed in the next season by capillary movement to the root zone of corn, and increased bioactivity of herbicide residues following liming of fields. Bioassays were employed to determine to what extent imazethapyr leached in a soil that typically contains less than 10% total clay and 0.1% organic C in the 0- to 300-mm zone and to assess the role of pH and liming in the bioactivity of the herbicide. Undisturbed soil columns were collected in polyvinyl chloride pipe for the leaching experiment. In the greenhouse, the equivalent of 40 g ai/ha imazethapyr was applied on the column surface, followed by leaching with simulated rain of 25 or 50 mm. Leaf area measurements of the test species rapeseed showed that the herbicide was readily leached to at least 30 cm at both water regimes and that it subsequently moved upward in the soil, with evaporation as the driving force. In the other bioassay, the soil was ameliorated with different amounts of Ca(OH)2 or CaCO3 to adjust pH levels to between 5.7 and 7.1 These soil samples were each treated with imazethapyr at rates equivalent to 1.8, 3.75, 7.5, 15, and 30 g ai/ha. The growth response of the test species indicated that where Ca(OH)2 was applied, the bioactivity of imazethapyr in most instances was significantly greater than where CaCO3 was used. At all the imazethapyr rates, the activity of the herbicide increased significantly with an increase in pH from 5.6 to 6.5 where Ca(OH)2 was used, but with CaCO3, activity was significant only at 15 and 30 g ai/ha. Changes in imazethapyr adsorption and in the organic matter in the soil were not monitored, but it is suggested that the increase in herbicide activity caused by Ca(OH)2 may be due to the degradation of organic matter in the soil or to desorption of the herbicide, which would render the herbicide more available for uptake. These effects, if they do occur, are likely to be of significance for herbicide adsorption only in soil with very low organic matter content. Results indicate that imazethapyr could leach easily in coarse-textured soils low in clay and organic matter content and that the type of lime used on those soils may influence the bioactivity of the herbicide.

Copyright

Corresponding author

Corresponding author's E-mail: creinhard@postino.up.ac.za.

References

Hide All
Anonymous. 1991. Technical information report on imazethapyr. Princeton, NJ: American Cynamid. Agricultural Research Division. 29 p.
Ashton, F. M. and Monaco, T. J. 1991. Weed Science: Principles and Practices. 3rd ed. New York: J. Wiley. 466 p.
Basham, G. W., Lavy, T. L., Oliver, L. R., and Scott, H. H. 1987. Imazaquin persistence in three Arkansas soils. Weed Sci. 35: 576582.
Beckie, H. J. and McKercher, R. B. 1990. Mobility of two sulfonylurea herbicides in soil. J. Agric. Food Chem. 38: 310315.
Buys, A. J. 1988. FSSA Fertilizer handbook. 2nd ed. Pretoria, South Africa: Fertilizer Association of South Africa. 331 p.
Enfield, C. G. and Yates, S. R. 1990. Organic chemical transport to groundwater. In Cheng, H. H., ed. Pesticides in the Soil Environment: Processes, Impact, and Modeling. Number 2. SSSA Book Series. Madison, WI: Soil Science Society of America Inc. pp. 271302.
Gan, J., Weimer, M. R., Koskinen, W. C., Buhler, D. D., Wyse, D. L., and Becker, R. L. 1994. Sorption and desorption of imazethapyr and 5-hydroxyimazethapyr in Minnesota soils. Weed Sci. 42: 9297.
Goetz, A. J., Wehtje, G., Walker, R. H., and Hajek, B. 1986. Soil solution and mobility characterization of imazaquin. Weed Sci. 34: 788793.
Goetz, A. J., Lavy, T. L., and Gbur, E. E. 1990. Degradation and field persistence of imazethapyr. Weed Sci. 38: 421428.
Günther, P., Rahman, A., and Pestemer, W. 1989. Quantitative bioassays for determining residues and availability to plants of sulphonylurea herbicides. Weed Res. 29: 141146.
Henning, J.A.G. and von M. Harmse, H. J. 1993. The effect of soil characteristics and rainfall on the presence and seasonal fluctuations of water tables in aeolian sand of the north-western Orange Free State. S. Afr. J. Plant Soil 10: 105109.
Henning, J.A.G. and Stoffberg, D. J. 1992. Effect of internal forces, associated with water tables, on consolidation of tillaged sand from the north-western Free State. Appl. Plant Sci. 6:47.
Koskinen, W. C. and Harper, S. S. 1990. The retention process: mechanisms. In Cheng, H. H., ed. Pesticides in the Soil Environment: Processes, Impact, and Modeling. Number 2. SSSA Book Series. Madison, WI: Soil Science Society of America. pp. 5178.
Loux, M. M. and Reese, K. D. 1993. Effect of soil type and pH on persistence and carryover of imidazolinone herbicides. Weed Technol. 7: 452458.
Loux, M. M., Liebl, R. A., and Slife, F. W. 1989. Adsorption of imazaquin and imazethapyr on soils, sediments and selected adsorbents. Weed Sci. 37: 712718.
Mangels, G. 1991. Behavior of the imidazolinone herbicides in soil—a review of the literature. In Shaner, D. L. and O'Connor, S. L., eds. The Imidazolinone Herbicides. New York: CRC Press. pp. 191209.
Nitsch, J. P. 1972. Phytotrons: past achievements and future needs. In Rees, A. R., Cockshull, K. E., Hand, D. W., and Hurd, R. G., eds. Crop Processes in Controlled Environments. London: Academic Press. pp. 3355.
O'Dell, J. D., Wolt, J. D., and Jardine, P. M. 1992. Transport of imazethapyr in undisturbed soil columns. Soil Sci. Soc. Am. J. 56: 17111715.
Oppong, F. K. and Sagar, R. 1992. The activity and mobility of triasulfuron in soil as influenced by organic matter, duration, amount and frequency of rain. Weed Res. 32: 157165.
Renner, K. A., Meggitt, W. F., and Penner, D. 1988. Effect of soil pH on imazaquin and imazethapyr adsorption to soil and phytotoxicity to corn (Zea mays). Weed Sci. 36: 7883.
Riley, D. and Eagle, D. 1990. Herbicides in soil and water. In Hance, R. J. and Holly, K., eds. Weed Control Handbook: Principles. 8th ed. London: Blackwell Scientific. pp. 243259.
Santlemann, P. W. 1977. Herbicide bioassay. In Truelove, B., ed. Research Methods in Weed Science. 2nd ed. Auburn, AL: Southern Weed Science Society. pp. 7987.
Sigua, G. C., Isensee, A. R., and Sadeghi, A. M. 1993. Influence of rainfall intensity and crop residue on leaching of atrazine through intact no-till soil columns. Soil Sci. 156: 225232.
Stougaard, R. N., Shea, P. J., and Martin, A. R. 1990. Effect of soil type and pH on adsorption, mobility and efficacy of imazaquin and imazethapyr. Weed Sci. 38: 6773.
Streibig, J. C. 1988. Herbicide bioassay. Weed Res. 28: 479484.
Walsh, J. D., Defelice, M. S., and Sims, B. D. 1993. Soybean (Glycine max) herbicide carryover to grain and fiber crops. Weed Technol. 7: 625632.

Keywords

A Bioassay Technique Detects Imazethapyr Leaching and Liming-Dependent Activity

  • Leon J. Van Wyk (a1) and Carl F. Reinhardt (a1)

Metrics

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed