RESIDUAL WEED CONTROL IN PEANUT WITH CADRE, STRONGARM, VALOR,

1
RESIDUAL WEED CONTROL IN PEANUT WITH CADRE,
STRONGARM, VALOR, AND SPARTAN A MULTISTATE AND
MULTIYEAR SUMMARY
T.L. Grey, D.C. Bridges, E.F. Eastin, E.P.
Prostko, and W.K. Vencill - Univ. Georgia W.C.
Johnson, Jr.- USDA-ARS B.J. Brecke, G.E.
MacDonald, and J.A. Tredaway - Univ. Florida J.W.
Everest and G.R. Wehtje - Auburn Univ. J.W.
Wilcut - North Carolina State Univ.
Introduction Peanut development and maturity
require a long growing season and thus, the
residual activity of herbicides applied early
season may not provide effective season-long weed
control if no additional herbicides are applied.
Therefore, residual weed control is an important
part of peanut production. This is illustrated by
the fact that paraquat is often tank-mixed with
Basagran EPOT, but it is rarely used alone, that
is in the absence of other weed control
treatments because of the lack of residual
control. During the 1980's and 1990's, the
development and introduction of PPI, PRE, and
POST herbicides emphasized the control of
broadleaf, nutsedge, and grass species. Lack of
extended residual activity, variation in weed
control spectrum, rotational restrictions, and
cost are factors in herbicide selection. Until
recently, these factors have limited the
domination of any one particular herbicide in the
Southeastern United States peanut
market. Reviews of the herbicide options for
peanut weed control were conducted and published
in 1994 and 1995. However, since then the
residual herbicides available for peanut weed
control have changed Cadre (imazapic) was
registered in 1996 for POST application
Strongarm (diclosulam) was registered for PPI and
PRE application in 2000 Valor (flumioxazin) was
registered for PRE application in 2001 and
Spartan (sulfentrazone) is currently under
registration review. This review was conducted
to summarize current and future weed control
options for peanut producers, extension, and the
agchem industry. Weed control data from research
conducted from 1990-2000 by The University of
Georgia, University of Florida, and Auburn
University were compiled, reviewed, summarized,
and presented here. Materials Methods In
2001, Georgia scientists compiled data from over
100 experiments to conduct this review. The
review includes 23 treatments using PPI, PRE,
EPOST, and POST treatments of Cadre, Strongarm,
Valor, Spartan, and a standard, paraquat
Basagran (Table 1). Paraquat and paraquat-tank
mixtures were applied to 110 of the 1998 Georgia
peanut crop (unpublished data). Therefore,
paraquat Basagran was chosen as the standard
treatment. Twelve regionally important weeds
were selected based on a county extension survey
conducted in Georgia. Weed control was averaged
across tests and years to report average weed
control, standard deviation, and number of tests
for each of the 12 weeds when each herbicide was
applied alone and in combination with paraquat
Basagran.
Results Discussion All weed control ratings
reflect mid-season weed control (July) except for
Florida beggarweed, which are from late-season
ratings (September). For weed control results by
species when herbicides were applied alone refer
to Table 1. Sicklepod, Florida beggarweed, and
purple and yellow nutsedge are considered primary
common and troublesome weeds in southeastern
peanut fields. Sicklepod control with Cadre
alone was good fair with paraquat Basagran
and, poor with other herbicides alone. Florida
beggarweed control was good-excellent with Valor
fair-good with Strongarm fair with Cadre and
Spartan and poor-fair with paraquat Basagran.
Purple nutsedge control was excellent with Cadre
poor-fair with Spartan and poor with other
herbicides applied alone. Yellow nutsedge
control was excellent with Cadre and Spartan
good with Strongarm and poor with Valor and
paraquat Basagran. Control of other species
varied by treatment when herbicides were applied
alone. When herbicides were applied in
combination with paraquat Basagran, weed
control generally improved (Table
2). Conclusions The following is noteworthy
only Cadre controlled sicklepod only Valor
controlled Florida beggarweed greater than 90
Cadre controlled purple and yellow nutsedge
greater than 90 Spartan controlled yellow
nutsedge greater than 84 all herbicides gave
good-excellent morningglory control Strongarm
provided nearly 90 bristly starbur control at
all rates and application timings. Tables 3 and 4
show proposed weed response recommendations for
these herbicides. Acknowledgements The
authors appreciate the support of their
respective institutions and BASF, Dow
AgroScience, FMC, Syngenta, and Valent for their
support of this research.
Table 3.Weed Control Summary Applied Alone
Table 4. Weed Control Summary With paraquat
Basagran
Excellent gt89 Good 79-91 Fair 69-81 Poor
lt69. Cadre 1.44 oz/ac POST Strongarm 0.45 oz/ac
PPI Valor 3.0 oz/ac PRE Spartan 8.0 oz/ac
PRE paraquat Basagran, variable.