Skip to main content Accessibility help

Effects of Herbicide Application Timing on Johnsongrass (Sorghum halepense) and Pitted Morningglory (Ipomoea lacunosa) Control

  • David R. Shaw (a1), Sunil Ratnayake (a1) and Clyde A. Smith (a1)


Field experiments were conducted to evaluate the influence of application timing of imazethapyr and fluazifop-P on rhizome johnsongrass and pitted morningglory control in soybean. Herbicides were applied at three timings keyed to johnsongrass heights of 15, 30, and 60 cm and 3-, 6-, and 9-leaf pitted morningglory. Evaluations 6 wk after the final treatment indicated imazethapyr controlled both species best when applied at the 15-cm johnsongrass growth stage. Increasing imazethapyr rate did not increase control of pitted morningglory, but did increase johnsongrass control at the 15-cm application timing. However, at the 30-cm johnsongrass application timing, increasing the rate from 0.07 to 0.10 kg ha-1 improved control of both species. Johnsongrass control with imazethapyr was no more than 64% when applications were delayed to 30-cm or larger johnsongrass. Fluazifop-P controlled johnsongrass well at all timings.



Hide All
1. Baldwin, F. L., and Frans, R. E. 1972. Soybean and weed response to dinoseb and chloroxuron applied topically. Weed Sci. 20:511514.
2. Banks, P. A., and Tripp, T. N. 1983. Control of johnsongrass (Sorghum halepense) in soybeans (Glycine max) with foliar applied herbicides. Weed Sci. 31:626633.
3. Barker, M. A., Thompson, L. Jr., and Godley, F. M. 1984. Control of annual morningglories (Ipomoea spp.) in soybeans (Glycine max). Weed Sci. 32:813818.
4. Bryson, C. T. 1987. Effects of rainfall on foliar herbicides applied to rhizome johnsongrass. Weed Sci. 35:115119.
5. Dale, J. E. 1981. Control of johnsongrass (Sorghum halepense) and volunteer corn (Zea mays) in soybeans. Weed Sci. 29:708711.
6. Driver, J., and Frans, R. 1982. Selective postemergence control of johnsongrass in soybeans and cotton. Proc. South. Weed Sci. Soc. 35:27.
7. Elmore, C. D. 1986. Weed survey–Southern States. Res. Rep. South. Weed Sci. Soc. 39:136.
8. Horowitz, M. 1972. Early development of johnsongrass. Weed Sci. 20:271273.
9. Howe, O. W. III and Oliver, L. R. 1987. Influence of soybean (Glycine max) row spacing on pitted morningglory (Ipomoea lacunosa) interference. Weed Sci. 35:185193.
10. King, C. A., and Oliver, L. R. 1989. Timing of postemergence imazethapyr (Pursuit) applications. Proc. South. Weed Sci. Soc. 42:58.
11. McClelland, M. R., Oliver, L. R., Mathis, W. D., and Frans, R. E. 1978. Responses of six morningglory (Ipomoea) species to bentazon. Weed Sci. 26:459466.
12. Micheal, S. D., Williams, W. W., and Martin, J. R. 1987. Johnsongrass (Sorghum halepense) control and soil moisture relationships in no-tillage doublecropped soybeans (Glycine max). Weed Sci. 35:108114.
13. McWhorter, C. G., and Anderson, J. M. 1981. The technical and economic effects of johnsongrass (Sorghum halepense) control in soybeans (Glycine max). Weed Sci. 29:245253.
14. Muzyk, K. R., Dobson, J. B., O'Neil, J. B., Walls, F. R., Youmans, C. D., and Van Winkle, D. 1987. Pursuit: soybean efficacy traits in the Atlantic Coast Region. Proc. South. Weed Sci. Soc. 40:45.
15. Rogers, R. L., and Crawford, S. H. 1980. Weed control in soybeans with acifluorfen (Blazer). Proc. South. Weed Sci. Soc. 33:50.
16. Williams, C. S., and Hayes, R. M. 1984. Johnsongrass (Sorghum halepense) competition in soybeans (Glycine max). Weed Sci. 32:498501.
17. Vidrine, P. R., Reynolds, D. B., and Griffin, J. L. 1988. Performance of imazethapyr in soybeans. Proc. South. Weed Sci. Soc. 40:40.


Effects of Herbicide Application Timing on Johnsongrass (Sorghum halepense) and Pitted Morningglory (Ipomoea lacunosa) Control

  • David R. Shaw (a1), Sunil Ratnayake (a1) and Clyde A. Smith (a1)


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