Rye (Secale cerealeL.), used as a winter cover crop, was killed by paraquat or by mowing with a bushog. In the early stages of subsequent no-till corn, abundance of armyworm,Pseudaletia unipuncta(Haworth), was lower in the mowed treatment compared with the sprayed treatment in three of five fields and did not differ in another field. Over the duration of the first armyworm generation, cumulative armyworm-days in the sprayed treatment were greater than in the mowed treatment in three of five fields and did not differ in another field. Mowing the cover crop was 40% less expensive than spraying. Competition from rye regrowth in the mowed treatment did not diminish yields. Corn silage yields were increased by mowing (P= 0.07), and the average increase in net benefit from mowing the cover crop compared with spraying was 91–113/ha. Cover crop mowing may be an economical and effective means of managing armyworm populations in no-till corn.