Vol. 51—1997 - NorthEastern Weed Science Society

81
COMPARSON OF ATRAZINEANDPROSULFURONCOMBINATIONSWITH
PREEMERGENCEHERBICIDES IN SWEETCORN
Frank J. Himmelstein, Robert J. Durgy 1
ABSTRACT
A stud was initiated for fresh market sweet corn (Zea mays
saccharata .) to determine optimum reduced rate combinations of
standard la eled herbicides and to evaluate unlabeled and
recently la eled herbicides as alternatives to the standards. A
1996 field rial conducted on the Plant Science Research Farm in
Storrs, ct valuated four preemergence herbicides applied alone
and in co 'nation with atrazine applied preemergence or
prosulfuron (Peak) applied postemergence. The study was a split
plot desig with three replications. The main plots were atrazine
applied at 1.0 lb ai/A, prosulfuron applied at 0.036 lb ai/A, and
the preeme ence herbicide (PRE) treatments applied alone. The
sub-plot t atments and applied rates were: metolachlor[(Dual II)
2 and 2.5 ai/A],dimethenamid [(Frontier) 0.94 and 1.17 lb ai/
A], alachl [(Lasso MT) 2 and 2.5 lb ai/A], and pendimethalin
[(Prowl) a 1.25 and 1.5 lb ai/A]. Sweet corn "D'Artagnan" was
planted on ~ne 12. Preemergence treatments were applied on June
13. Prosul ron was applied on July 11, when the sweet corn was
at the 8-9 leaf stage, 25-40 cm in height. Herbicides were
applied wi a CO 2 backpack sprayer delivering 20 gpa at 32 psi.
Weed contr 1 was assessed by visual ratings, and weed biomass
samples ta en from a 2.25 ft 2 quadrat from the center of each
plot. The ominant weed species were common lambsquarters
(Cheno odi m album L.), common ragweed (Ambrosia artemisiifolia
L.), redro t pigweed (Amaranthus retroflexus L.), and large
crabgrass Digitaria sanguinalis (L.) Scop.] The atrazine and
prosulfuro treatments gave greater control of redroot pigweed
and common lambs quarter compared to the PRE treatments. Common
ragweed co trol was 100% for the prosulfuron treatments. There
were no di ferences in common ragweed control between the
atrazine a d PRE treatments. Large crabgrass control was similar
among the ain treatment effects. Alachlor gave 100% control of
redroot pi eed although pigweed biomass was similar between
herbicide reatments. Pendimethalin gave greater lambsquarters
control co pared to the other herbicides. All herbicide
treatments gave similar control of large crabgrass and common
ragweed. W ed control was similar between the low and high
herbicide ates for all weed species. A single harvest of all
ears from wo 10 foot center rows indicated the sweet corn yield
from the p osulfuron plots were reduced 20% compared to the
atrazine a d PRE treatments. There were no differences in sweet
corn yield among the SUb-plot treatments or application rates.
Culls were not determined for each plot. A random sampling of
sweet corn ears indicated the yield reduction attributed to the
prosulfuro treatments was more likely due to delayed maturity
rather tha actual kernel loss. Further studies will be needed.
Extens10n Educator-Integrated Crop Management, and Res. Asst.,
respective y, University of connecticut, storrs, CT 06269