Published online by Cambridge University Press: 20 January 2017
The effect of weed interference on corn yield and the critical period forweed control (CPWC) were determined in Germany and Benin. Treatments withweed control starting at different crop growth stages and continuously keptweed-free until harvest represented the “weed-infested interval.” Treatmentsthat were kept weed-free from sowing until different crop growth stagesrepresented the “weed-free interval.” Michaelis–Menten, Gompertz, logisticand log–logistic models were employed to model the weed interference onyield. Cross-validation revealed that the log–logistic model fitted theweed-infested interval data equally well as the logistic and slightly betterthan the Gompertz model fitted the weed-free interval. For Benin, economiccalculations considered yield revenue and cost increase due to mechanicalweeding operations. Weeding once at the ten-leaf stage of corn resultedalready profitable in three out of four cases. One additional weedingoperation may optimize and assure profit. Economic calculations for Germanydetermined a CPWC starting earlier than the four-leaf stage, challenging thedecade-long propagated CPWC for corn. Differences between Germany and Beninare probably due to the higher yields and high costs in Germany. This studyprovides a straightforward method to implement economic data in thedetermination of the CPWC for chemical and nonchemical weed controlstrategies.