Jr. Watts et al., SICKLEPOD (SENNA-OBTUSIFOLIA) CONTROL IN SOYBEAN (GLYCINE-MAX) WITH SINGLE AND SEQUENTIAL HERBICIDE APPLICATIONS, Weed technology, 11(1), 1997, pp. 157-163
Field studies were conducted in 1991 to 1993 to determine the effects
of PRE and POST herbicides alone and in factorial combinations on sick
lepod control, weed biomass, and soybean seed yields. Herbicides evalu
ated were metribuzin PRE, metribuzin + chlorimuron PRE, imazaquin PRE
and POST, chlorimuron POST, and AC 263,222 POST. POST herbicides alone
provided better sicklepod control than PRE herbicides alone. However,
sequential (SEQ) treatments [PRE followed by (fb) POST] provided bett
er sicklepod control than single herbicide treatments. Metribuzin and
metribuzin + chlorimuron alone or used in a SEQ program provided simil
ar PRE control of sicklepod, and both controlled sicklepod better than
imazaquin in 1991 and 1992. Chlorimuron alone or in a SEQ program pro
vided better POST control than AC 263,222 or imazaquin alone when soil
moisture levels at planting favored weed seed germination. When soil
moisture levels at planting were unfavorable for weed seed germination
, the residual activity of imazaquin provided the best season-long con
trol. SEQ herbicide applications allowed soybean to attain higher seed
yields than single (PRE or POST) herbicide treatments all 3 yr. Howev
er, only metribuzin fb chlorimuron in 1991 and 1992 and imazaquin fb i
mazaquin and imazaquin fb chlorimuron in 1993 allowed soybean to achie
ve seed yields similar to weed-free soybean. Soybean seed yields were
greater with POST than with PRE herbicides 2 of 3 yr, but no single he
rbicide treatment provided soybean seed yields similar to weed-free so
ybean.