Vol. 51—1997 - NorthEastern Weed Science Society

56
EDUCEDRATE PREEMERGENCEHERBICIDE COMBINATIONSWITH
ISOXAFLUTOLEOR PENDIMETHALININ FIELD CORN
Frank J. Himmelstein, Robert J. Durgy 1
ABSTRACT
I oxaflutole (Balance) and pendimethalin (Prowl) are
effect've weed control options in field corn (Zea mays L.). Two
1996 f'eld trials conducted in Lebanon, CT evaluated seven
preeme gence herbicides applied alone and in combination with
isoxaf utole or pendimethalin. The studies were split plot
design with three replications. The main plots were isoxaflutole
applie at 1.5 oz ai/A, pendimethalin applied at 1.5 lb ai/A, and
the pr emergence herbicide (PRE) treatments applied alone. The
sub-pI t treatments and applied rates were: thiafluamide +
metrib zin [(Axiom) 0.32 and 0.64 lb ai/A], flumetsulam +
clopyr lid [(Broadstrike Plus) 0.125 and 0.25 lb ai/A],
metola hlor [(Dual II) 1 and 2 lb ai/A], dimethenamid [(Frontier)
0.47 a d 0.94 lb ai/A], acetochlor [(Harness) 0.88 and 1.75 lb
ai/A], alachlor [(Lasso MT) 1 and 2 lb ai/A], and acetochlor +
safene [(Surpass) 0.9 and 1.8 lb ai/A]. Herbicides were applied
with a CO 2 backpack sprayer delivering 20 gpa at 32 psi. Weed
contro was assessed by visual ratings, and weed biomass samples
taken rom a 2.25 ft 2 quadrat from the center of each plot.
Common lambsquarters (Chenopodium album L.) was the dominant weed
at the Savin Farm site. Isoxaflutole and pendimethalin treatments
gave e cellent common lambsquarters control as indicated by weed
rating and weed biomass samples taken 38 and 78 OAT,
respec ively. Common lambsquarters biomass was reduced 100% with
the is xaflutole and pendimethalin treatments, and 70% for the
PRE tr atments compared to the check. Velvetleaf (Abutilon
theo h asti Medik.) control was lower for the PRE treatments
compar d to the isoxaflutole and pendimethalin treatments. Common
ragwee (Ambrosia artemisiifolia L.) proliferated in several
pendim thalin treatments. Isoxaflutole treatments resulted in
100% c romon ragweed control. All treatments gave effective
redroo pigweed (Amaranthus retroflexus L.) control. Redroot
pigwee , common lambsquarters, and velvetleaf were the dominant
weeds t the Grabber Farm site. Weed ratings taken 39 OAT
indica ed both the isoxaflutole and pendimethalin treatments gave
greate control (95-100%) of all three weed species compared to
the PR treatments. The PRE treatments gave 29%, 81% and 92%
contro of velvetleaf, common lambsquarters, and redroot pigweed,
respec ively. Weed biomass samples taken 76 OAT indicated there
were n differences in redroot pigweed biomass between the main
treatm nt effects. Velvetleaf and common lambsquarters biomass
was gr ater for the PRE treatments compared to the isoxaflutole
and pe dimethalin treatments. Where triazine resistant weeds are
presen , both isoxaflutole and pendimethalin will provide
effect ve redroot pigweed, common lambsquarters and velvetleaf
contro • Isoxaflutole will provide effective ragweed control.
Extens~on Educator-Integrated Crop Management, and Res. Asst.,
respec ively, University of Connecticut, Storrs, CT 06269