Field experiments were conducted in North Carolina hom 1994 through 1998 to
evaluate the effects of five weed management strategies and four corn (Zea
mays)-peanut: (Aratchis hypogaea) rotation sequences on purple nutsedge (C
yperus rotundus) population development. Effects of these weed management p
rograms on cotton (Gossypium hirsutum) and peanut production in following y
ears were also investigated. Herbicide programs included a nontreated contr
ol, a carbamothioate preplant incorporated (PPI) combination treatment util
izing vernolate in peanut and butylate in corn, an early postemergence (EPO
ST) acetolactate synthase (ALS) inhibitor combination treatment utilizing i
mazapic in peanut and halosulfuron in corn, and EPOST treatments of imazapi
c and imazethapyr in both peanut and imidazolinone-resistant corn. Crop rot
ation sequences for the 3 yr included continuous corn (CCC), peanut-corn (C
PC), peanut-corn-peanut (PCP), and continuous peanut (PPP). The imazapic an
d ALS inhibitor combination treatments both provided excellent shoot and tu
ber control, After 3 yr, imaaapic and the ALS inhibitor combination treatme
nt reduced shoot and tuber population densities to less than 10% of the non
treated control. Imazethapyr provided variable but better control than the
carbamothioate treatment; with tuber densities (measured from 0 to 15 cm so
il depth) and shoot densities increasing from 733 to 2,901 tubers/m(3) of s
on and 16 to 43 shoots/m(2), respectively, after 3 yr, Tuber densities incr
eased in the nontreated control from 626 to 9,145 tubers/m(3) of soil and f
rom 962 to SfC64 tubers/m(3) of soil in the carbamothioate treatment during
this same period. Also, shoot densities increased in the nontreated contro
l from 22 to 159 shoots/m(2) and from 8 to 92 shoots/m(2) in the carbamothi
oate treatment. There was a 31% peanut yield reduction from 1994 to 1996 wh
en peanut was continuously planted or rotated to corn for only 1 yr. Herbic
ide carryover effects were not observed in cotton during 1997.