Vol. 51—1997 - NorthEastern Weed Science Society

32
R1MSULFURONITIIIFENSULFURON ACTIVITY IN NO-TILL CORN
P. A. KALNAY AND S. GLENN!
ABSTRACT
Gi t foxtail (Setariajaberi), common lambsquarters (Chenopodiumalbum), and hemp
dogbane ( 'pocynumcannabinum) control in no-till com (Zea mays) following POST applications
of a pack e mixof rimsulfuronlthifensulfuron alone or in combination with various herbicides
were studi d in Western Maryland. Experiments were designed as a randomized complete block
with 3 rep cations and a plot size of6 rows (30 inches) by 35 feet. Postemergence treatments
were appli d when giant foxtail and common lambsquarters were 2 to 4 inches high and hemp
dogbane s 6 to 20 inches high. In 1995 and 1996, giant foxtail control ranged from 82 to 85%
and 75 to 0%, respectively 8 weeks after treatment (WAT) with rimsulfuronlthifensulfuron
(0.016 and 0.0311bs IA) applied alone. Giant foxtail that was not controlled with POST
applicatio of rimsulfuronlthifensulfuron emerged after applications. Lower giant foxtail control
in 1996 co pared to 1995 was due to greater emergence of the grass after POST applications in
1996 than 995. Applications of rimsulfuronlthifensulfuron alone completely controlled
lambsqu ers (100%) 8 WAT, but hemp dogbane control was poor (27 to 33%). Tank mixtures
of primisu ron, halosulfuron, or primisulfuronlprosulfuron with 0.016 lbslA rimsulfuronl
thifensulfu on produced similar giant foxtail (65 to 82%) and lambsquarters control (100%), but
poor hem dogbane control (30 to 47%). Tank mixtures ofO.016lbslA rimsufuronlthifensulfuron
with 0.12 and 0.25 Ibs/A dicamba controlled giant foxtail (75 and 77%) and lambsquarters
(100010),b t combinations with 0.51bslA dicamba reduced giant foxtail control (63%). All
dicamba c mbinations with rimsulfuronlthifensulfuron improved hemp dogbane control compared
to rims onlthifensulfuron applied alone. Hemp dogbane control following combinations with
0.0125, O. 5, and 0.51bslA dicamba was 68,83, and 80%, respectively. Postemergence
applicatio s of rimsulfuronlthifensulfuron effectively controlled giant foxtail and lambsquarters,
but comb' ations with dicamba were required to control the perennial broadleafweed, hemp
dogbane.
1 ad. Res. Asst. and Assoc. Prof, Dept. of Agronomy, University of Maryland, College
Park, 20742.