Malheur Experiment Station
|
Information for Sustainable Agriculture
|
DUAL MAGNUM® APPLICATIONS FOR WEED CONTROL IN SUGAR BEET
Corey V. Ransom, Charles A. Rice, and Joey K. Ishida
Malheur Experiment Station
Oregon State University
Ontario, OR, 2003
Introduction
Dual Magnum (s-metolachlor) was labeled in the
spring of 2003 for pre-plant incorporated (PPI), preemergence (PRE),
and postemergence (POST) applications to sugar beet. Presently, because
of injury from PPI and PRE applications to sugar beet this past season
in the Red River Valley of North Dakota and Minnesota, the future label
status of these application methods is uncertain. The objective of this
trial was to evaluate weed control and crop response with PPI, PRE, and
POST Dual Magnum applications in sugar beet.
Methods
This trial was conducted in a furrow-irrigated
field near Nampa, Idaho. Dual Magnum was applied PPI, PRE, or POST to
two-leaf beets at 1.27 or 1.59 lb ai/acre. Nortron (ethofumesate) was
applied PPI and PRE at 1.6 lb ai/acre for comparison. Herbicide
treatments were broadcast-applied with a CO2-pressurized
backpack sprayer calibrated to deliver 20 gal/acre at 30 psi. Plots
were four rows wide and 27 ft long and treatments were arranged in a
randomized complete block design with four replicates. PPI, PRE, and
POST treatments were applied on April 17, April 29, and May 23,
respectively. PPI treatments were incorporated immediately after
application with an Alloway field cultivator equipped with s-tines and
rolling baskets. Sugar beets were planted following incorporation. The
timing of the PRE applications was not ideal as approximately 20
percent of the sugar beets had already begun to emerge. A standard rate
herbicide program consisting of three POST applications of Progress
(ethofumesate + desmedipham + phenmedipham), UpBeet (triflusulfuron),
and Stinger (clopyralid) was broadcast over the entire experimental
area independent of Dual Magnum and Nortron applications. Sugar beet
injury and weed control were evaluated throughout the season. Sugar
beet stand populations/20 ft of row were recorded on May 23 following
PPI and PRE applications. Data were analyzed using analysis of variance
procedures and means were separated using protected LSD at the 95
percent confidence interval (P = 0.05). The trial was not harvested.
Results and Discussion
Sugar beet stand populations on May 23 ranged
from 32 to 36 plants/20 ft of row and were not different among
treatments (Table 1). Sugar beet injury on May 23 was greatest with the
PRE treatments. This injury was most likely enhanced because the PRE
treatments were applied late and approximately 20 percent of the beets
were beginning to emerge, allowing for direct herbicide contact. Sugar
beet injury with Nortron was less than with Dual Magnum applied at 1.59
lb ai/acre on May 23 and June 13 and when applied at 1.27 lb ai/acre on
June 13. Injury was not different between the PPI treatments and the
standard rate program alone. There were no differences in weed control
among the PPI treatments (Table 1). The PRE treatments gave similar
control of all evaluated weed species. Redroot pigweed control was less
with POST Dual Magnum applications than with PPI or PRE treatments of
Dual Magnum or Nortron. POST applications of Dual Magnum were applied
after many of the weeds had emerged and therefore they were
considerably less effective. POST Dual Magnum at either application
rate did not improve control of the evaluated weeds when compared to
the standard rate alone. Control of kochia, hairy nightshade, and
common lambsquarters were similar with Dual Magnum applied POST at 1.59
lb ai/acre and with all PRE treatments. However, when Dual Magnum was
applied POST at 1.27 lb ai/acre, control of these weeds was less than
with the PRE treatments. Similar control of kochia, hairy nightshade,
and common lambsquarters was achieved with all PPI and PRE treatments.
Table 1. Weed control and crop response with Dual
Magnum applications in sugar beet, Malheur Experiment Station, Oregon
State University, Ontario, OR, 2003.
|
|
|
Sugar beet |
|
Weed control§ |
|
|
|
Stand |
|
Injury ‡ |
|
Redroot pigweed |
Kochia |
Hairy nightshade |
C. Lambs- quarters |
Treatment* |
Rate |
Timing† |
5-23 |
|
5-23 |
6-13 |
|
8-14 |
8-14 |
8-14 |
8-14 |
|
lb ai/acre |
|
No./20 ft |
|
----------- % ----------- |
|
------------------------------- % ------------------------------- |
Standard rate w/out soil-active |
-- |
-- |
36 |
|
12 |
1 |
|
41 |
87 b |
91 c |
61 |
|
|
|
|
|
|
|
|
|
|
|
|
Nortron |
1.6 |
PPI |
34 |
|
18 |
16 |
|
76 |
95 ab |
98 ab |
95 |
|
|
|
|
|
|
|
|
|
|
|
|
Dual Magnum |
1.27 |
PPI |
33 |
|
15 |
14 |
|
86 |
100 a |
89 a |
99 |
|
|
|
|
|
|
|
|
|
|
|
|
Dual Magnum |
1.59 |
PPI |
32 |
|
19 |
16 |
|
82 |
94 ab |
93 a |
99 |
|
|
|
|
|
|
|
|
|
|
|
|
Nortron |
1.6 |
PRE |
36 |
|
30 |
12 |
|
85 |
100 a |
100 ab |
98 |
|
|
|
|
|
|
|
|
|
|
|
|
Dual Magnum |
1.27 |
PRE |
32 |
|
38 |
23 |
|
93 |
100 a |
100 a |
96 |
|
|
|
|
|
|
|
|
|
|
|
|
Dual Magnum |
1.59 |
PRE |
33 |
|
44 |
21 |
|
97 |
100 a |
100 a |
99 |
|
|
|
|
|
|
|
|
|
|
|
|
Dual Magnum |
1.27 |
POST |
36 |
|
11 |
5 |
|
25 |
75 b |
80 c |
63 |
|
|
|
|
|
|
|
|
|
|
|
|
Dual Magnum |
1.59 |
POST |
36 |
|
13 |
14 |
|
28 |
93 ab |
88 bc |
74 |
|
|
|
|
|
|
|
|
|
|
|
|
LSD (0.05) |
-- |
-- |
NS |
|
8 |
8 |
|
17 |
-- |
-- |
25 |
*A standard rate herbicide program was blanketed
over the entire plot area independent of Dual Magnum and Nortron
applications. †PPI applications were made on April 17, PRE on April 29, and POST on May 23, 2003.
‡PRE treatments were applied when
approximately 20 percent of the sugar beets had just emerged and most
likely increased injury with these treatments. POST treatments had not
yet been applied at the May 23 evaluation.
§In columns where letter
designations appear the ANOVA was performed on arcsine square root
percent transformed data. Mean separations were applied to
non-transformed data. Values with the same letter designations are
similar (P = 0.05).
MES
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For
additional information about the Malheur Agricultural Experiment
Station, please send an e-mail request to:
Dr. Clinton C. Shock
Clinton.Shock@oregonstate.edu
Malheur Agricultural Experiment
Station
595 Onion Avenue
Ontario, OR 97914
(541) 889-2174
FAX (541) 889-7831
Last updated
Wednesday July 7, 2004 .
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