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TIMING OF DUAL
MAGNUM® AND OUTLOOK® 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, 2004
Introduction
Outlook® (dimethenamid-P)
and Dual Magnum® (s-metolachlor) are soil-active herbicides that are
labeled for postemergence application in sugar beet. They can be applied to two-leaf or larger beets. Outlook or Dual Magnum was applied at
different timings as part of a standard rate herbicide program. The objectives of this trial were to 1)
determine if weed control can be improved with Outlook or Dual Magnum in the
standard rate program, and 2) determine if the application timing of these
herbicides influences weed control or crop response.
Methods
This trial was established at the
Malheur Experiment Station under furrow irrigation on April 8, 2004. Sugar beets (Hilleshog 'PM-21') were planted
in 22-inch rows at a 2-inch seed spacing.
On April 9, the trial was corrugated and Counter 20 CR® was
applied in a 7-inch band over the row at 6 oz/1,000 ft of row. Sugar beets were thinned to 8-inch spacing
on May 10 to 13. Plots were sidedressed
on June 2 with 175 lb nitrogen (N) (urea), 30 lb potash (K2O), 35 lb
sulfates (SO4), 38 lb elemental sulfur (S), 3 lb manganese (Mn), 2
lb zinc (Zn), and 1 lb/acre boron (B).
All plots were treated with Roundup® (0.75 lb ai/acre) on
April 13 prior to sugar beet emergence.
On May 26, Temik 15G® (14 lb
prod/acre) was applied for sugar beet root maggot control. For powdery mildew control, Headline®
(12 fl oz/acre) was applied on June 25, Topsin M® (20 oz prod/acre)
plus S at 6 lb/acre, phosphate (P2O5) at 1.5 lb/acre, and
Zn at 0.2 lb/acre were applied on August 4, and Headline (12 fl oz/acre) plus S
at 6 lb/acre were applied on August 8.
All fungicide treatments were applied by air. Herbicide treatments were broadcast applied with a CO2-pressurized
backpack sprayer calibrated to deliver 20 gal/acre at 30 psi. Plots were 4 rows wide and 27 ft long and
treatments were arranged in a randomized complete block design with 4
replicates.
Outlook, Dual Magnum, and Treflan®
were applied at various timings as part of a standard rate herbicide program to
evaluate the effect of application timing on weed control and crop
response. The standard rate program
consisted of Progress® applied at 4.0, 5.4, and 6.7 oz ai/acre in
the first, second, and third applications, respectively. UpBeet® was applied at 0.25 oz
ai/acre in all three applications and Stinger® at 1.5 oz ai/acre in
the last two applications. Dual Magnum
was applied preemergence only, or in the second or third postemergence
application, or preemergence and in the second application, or in the second
and third applications. Outlook was
applied in the second or third applications.
Both Dual Magnum and Outlook were applied in combination with Treflan in
the second postemergence application.
The preemergence treatments were applied April 13. The first, second, and third postemergence
applications were made on April 26, May 3, and May 14, to cotyledon, 2- to
4-leaf, and 6- to 10-leaf beets, respectively.
Sugar beet injury was evaluated on May
10 and June 9 and weed control was evaluated on September 3. Sugar beet yields were determined by
harvesting the center two rows of each plot on October 8 and 9. Root yields were adjusted to account for a 5
percent tare. One sample of 16 beets was taken from each plot for
quality analysis. The samples were
coded and sent to Syngenta Seeds Research Station in Nyssa, Oregon, to determine beet pulp sucrose
content and purity. Sucrose content and
recoverable sucrose were estimated using empirical equations. 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 untreated control was not included in the analysis of
variance for weed control or crop response.
Results and
Discussion
The addition of Outlook or Dual Magnum
or combinations of Outlook or Dual Magnum with Treflan improved barnyardgrass
control compared to the standard postemergence treatment alone (Table 1). For all other weeds, control was similar
among treatments. There also were no
differences in sugar beet injury (Table 2) or sugar beet stand (data not shown)
among treatments. All herbicide
treatments had greater yields compared to the untreated control, but yields did
not differ among herbicide treatments.
This research suggests that both Dual
Magnum and Outlook can be applied in combination with standard rate herbicides
in sugar beets without significant sugar beet injury. No injury was observed with preemergence applications of Dual
Magnum in this trial. However, in other
sugar beet production regions, under extremely wet conditions, Dual Magnum has
caused sugar beet injury when applied preemergence. In 2004, weather conditions were favorable and maximized the weed
control provided by postemergence herbicide treatments. Under different environmental conditions,
Dual Magnum or Outlook may have provided increased levels of broadleaf weed
control. Besides helping control annual
weeds, both Dual Magnum and Outlook are effective in suppressing yellow
nutsedge in sugar beet.
Table 1. Weed control in sugar beet
with standard rate herbicide treatments including postemergence applications of
Outlook® and Dual Magnum®, Malheur Experiment Station, Oregon
State University, Ontario, OR, 2004.
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Weed control† |
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Treatment |
Rate |
Timing* |
Kochia |
Pigweed Spp. |
Lambs- quarters |
Hairy nghtshade |
Barnyard- grass |
|
|
oz ai/acre |
|
--------------------------------------- %-------------------------------- |
||||
|
Untreated control |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
|
Progress + UpBeet +
Dual Magnum Progress + UpBeet +
Stinger + Dual Magnum Progress + UpBeet + Stinger |
4.0 + 0.25 + 15.3 5.4 + 0.25 + 1.5 + 15.3 6.7 + 0.25 + 1.5 |
1 2 3 |
100 |
100 |
100 |
100 |
100 |
|
Progress + UpBeet Progress + UpBeet +
Stinger + Dual Magnum Progress + UpBeet + Stinger |
4.0 + 0.25 5.4 + 0.25 + 1.5 + 15.3 6.7 + 0.25 + 1.5 |
1 2 3 |
100 |
100 |
100 |
100 |
97 |
|
Progress + UpBeet Progress + UpBeet +
Stinger + Dual Magnum Progress + UpBeet +
Stinger + Dual Magnum |
4.0 + 0.25 5.4 + 0.25 + 1.5 + 15.3 6.7 + 0.25 + 1.5 + 15.3 |
1 2 3 |
100 |
100 |
100 |
100 |
100 |
|
Dual Magnum Progress + UpBeet Progress + UpBeet +
Stinger + Dual Magnum Progress + UpBeet + Stinger |
20.3 4.0 + 0.25 5.4 + 0.25 + 1.5 + 15.3 6.7 + 0.25 + 1.5 |
PRE 1 2 3 |
100 |
100 |
100 |
100 |
100 |
|
Progress + UpBeet Progress + UpBeet +
Stinger Progress + UpBeet + Stinger |
4.0 + 0.25 5.4 + 0.25 + 1.5 6.7 + 0.25 + 1.5 |
1 2 3 |
99 |
100 |
100 |
100 |
84 |
|
Dual Magnum Progress + UpBeet Progress + UpBeet +
Stinger Progress + UpBeet + Stinger |
20.3 4.0 + 0.25 5.4 + 0.25 + 1.5 6.7 + 0.25 + 1.5 |
PRE 1 2 3 |
100 |
100 |
100 |
100 |
100 |
|
Progress + UpBeet Progress + UpBeet +
Stinger Progress + UpBeet + Stinger + Dual Magnum |
4.0 + 0.25 5.4 + 0.25 + 1.5 6.7 + 0.25 + 1.5 + 15.3 |
1 2 3 |
100 |
100 |
100 |
100 |
98 |
|
Progress + UpBeet Progress + UpBeet +
Stinger + Outlook Progress + UpBeet + Stinger |
4.0 + 0.25 5.4 + 0.25 + 1.5 + 13.4 6.7 + 0.25 + 1.5 |
1 2 3 |
100 |
100 |
100 |
100 |
100 |
|
Progress + UpBeet Progress + UpBeet +
Stinger + Outlook + Treflan Progress + UpBeet + Stinger |
4.0 + 0.25 5.4 + 0.25 + 1.5 + 13.4 + 8.0 6.7 + 0.25 + 1.5 |
1 2 3 |
100 |
100 |
100 |
100 |
100 |
|
Progress + UpBeet Progress + UpBeet +
Stinger Progress + UpBeet + Stinger + Outlook |
4.0 + 0.25 5.4 + 0.25 + 1.5 6.7 + 0.25 + 1.5 + 13.4 |
1 2 3 |
100 |
100 |
100 |
100 |
98 |
|
Progress + UpBeet Progrees + UpBeet +
Stinger + Dual Magnum + Treflan Progress + UpBeet + Stinger |
4.0 + 0.25 5.4 + 0.25 + 1.5 + 15.3 + 8.0 6.7 + 0.25 + 1.5 |
1 2 3 |
100 |
100 |
100 |
100 |
98 |
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LSD (0.05) |
-- |
-- |
NS |
NS |
NS |
NS |
6 |
*Application timings were (PRE) April 13, (1) April 26 to
cotyledon beets, (2) May 3 to 2- to 4-leaf beets, and (3) May 14 to 6- to
10-leaf beets.
†Weed control
was evaluated October 8 and 9. Pigweed
species included Powell amaranth and redroot pigweed.
Table 2. Sugar beet
injury and yield with standard rate herbicide treatments including
postemergence applications of Outlook®
and Dual Magnum®, Malheur Experiment
Station, Oregon State University, Ontario, OR, 2004.
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Sugar beet |
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Injury |
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Yield† |
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Treatment |
Rate |
Timing* |
5-10 |
6-9 |
|
Root yield |
Sucrose |
Extraction |
ERS |
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|
oz ai/acre |
|
------ % ----- |
|
ton/acre |
---------- % ---------- |
lbs/acre |
||
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Untreated control |
-- |
-- |
-- |
-- |
|
11.9 |
17.4 |
93.4 |
3,901 |
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Progress + UpBeet + Dual Magnum Progress + UpBeet +
Stinger + Dual Magnum Progress + UpBeet + Stinger |
4.0 + 0.25 + 15.3 5.4 + 0.25 + 1.5 + 15.3 6.7 + 0.25 + 1.5 |
1 2 3 |
24 |
9 |
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46.0 |
17.5 |
93.6 |
15,019 |
|
Progress + UpBeet Progress + UpBeet +
Stinger + Dual Magnum Progress + UpBeet + Stinger |
4.0 + 0.25 5.4 + 0.25 + 1.5 + 15.3 6.7 + 0.25 + 1.5 |
1 2 3 |
27 |
13 |
|
43.0 |
16.8 |
93.4 |
13,594 |
|
Progress + UpBeet Progress + UpBeet +
Stinger + Dual Magnum Progress + UpBeet +
Stinger + Dual Magnum |
4.0 + 0.25 5.4 + 0.25 + 1.5 + 15.3 6.7 + 0.25 + 1.5 + 15.3 |
1 2 3 |
21 |
20 |
|
44.1 |
17.0 |
93.4 |
14,053 |
|
Dual Magnum Progress + UpBeet Progress + UpBeet +
Stinger + Dual Magnum Progress + UpBeet + Stinger |
20.3 4.0 + 0.25 5.4 + 0.25 + 1.5 + 15.3 6.7 + 0.25 + 1.5 |
PRE 1 2 3 |
35 |
20 |
|
41.8 |
17.3 |
93.7 |
13,506 |
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Progress + UpBeet Progress + UpBeet +
Stinger Progress + UpBeet + Stinger |
4.0 + 0.25 5.4 + 0.25 + 1.5 6.7 + 0.25 + 1.5 |
1 2 3 |
25 |
11 |
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44.3 |
17.8 |
93.7 |
14,717 |
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Dual Magnum Progress + UpBeet Progress + UpBeet +
Stinger Progress + UpBeet + Stinger |
20.3 4.0 + 0.25 5.4 + 0.25 + 1.5 6.7 + 0.25 + 1.5 |
PRE 1 2 3 |
31 |
16 |
|
42.1 |
17.2 |
93.4 |
13,552 |
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Progress + UpBeet Progress + UpBeet +
Stinger Progress + UpBeet + Stinger + Dual Magnum |
4.0 + 0.25 5.4 + 0.25 + 1.5 6.7 + 0.25 + 1.5 + 15.3 |
1 2 3 |
27 |
13 |
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44.4 |
17.1 |
93.4 |
14,191 |
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Progress + UpBeet Progress + UpBeet +
Stinger + Outlook Progress + UpBeet + Stinger |
4.0 + 0.25 5.4 + 0.25 + 1.5 + 13.4 6.7 + 0.25 + 1.5 |
1 2 3 |
30 |
24 |
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