Biorational approaches to managing Datura stramonium

Field experiments were conducted from 1995 to 1997 to rest approaches to ma naging atrazine-resistant Datura stramonium. Eight weed management programs in a Zea mays and Glycine max rotation were evaluated for their effects on the dynamics of atrazine-resistant and -susceptible D. stramonium populati ons. Overall D, stramonium density and relative abundance of resistant (R) biotypes were greatly reduced in no-till Secale cereale L. (rye) cover crop management, programs without triazine compared to conventional-tillage sys tems with the application of triazine herbicides. The negative effects of n o-till on D, stramonium were greater under a G. max-Z. mays-G. max (SCS) ro tation than under a Z. mays-G. max-Z. mays (CSC) rotation. A cropping syste m involving more G. max phases under no-till reduced both the resistant and susceptible D. stramonium populations. Results from this study support the use of soil management, crop rotation, and negative cross-resistant herbic ides to manage atrazine-resistant biotypes.