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KOCHIA CONTROL
WITH PREEMERGENCE NORTRON® IN STANDARD AND MICRO-RATE HERBICIDE
PROGRAMS IN SUGAR BEET
Corey V. Ransom, Charles A. Rice, and Joey K. Ishida
Malheur Experiment Station
Oregon State University
Ontario, OR, 2004
Introduction
The distribution of kochia resistant to
UpBeet®
(triflusulfuron) herbicide and other acetolactate synthase (ALS) inhibitors
(i.e., sulfonylureas, imidazolinones, and triazolopyrimidines) has increased in
recent years and poses a serious problem in sugar beet production, as none of
the currently registered postemergence herbicides effectively control
ALS-resistant kochia. In this trial,
Nortron®
(ethofumesate) was evaluated for preemergence control of kochia in sugar
beet. Nortron is a soil-active
herbicide used preemergence or early postemergence to control annual grasses
and broadleaf weeds.
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 (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 August 4, and Headline (12 fl oz/acre) plus S at 6 lb/acre
were applied 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.
The treatments in this trial consisted
of both standard and micro-rate postemergence weed control programs applied
with or without a preemergence application of Nortron at either 16, 24, or 32
oz ai/acre with and without postemergence UpBeet. For the micro-rate treatment without UpBeet, Nortron was also
applied preemergence at 48 oz ai/acre.
UpBeet was omitted from selected treatments to simulate ALS resistance
and to better evaluate preemergence Nortron efficacy on kochia. Nortron was applied preemergence on April
13. The standard rate program included
three applications, with the first applied to full cotyledon sugar beets on
April 26, the second to two- to four-leaf sugar beets on May 3, and the third
application to six- to eight-leaf sugar beets on May 14. Progress (ethofumesate + phenmedipham +
desmedipham) was 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
(excluding treatments where UpBeet was omitted). Stinger®
(clopyralid) was applied in the second and third applications at 1.5 oz ai/acre. The micro-rate program consisted of four
applications with the first applied to cotyledon sugar beets on April 23, the
second to cotyledon to 2-leaf sugar beets on April 30, the third application
was inadvertently delayed and was applied to 8- to 10-leaf sugar beets on May
15, and the fourth to 8- to 12-leaf sugar beets on May 20. In the micro-rate program, Progress® was applied at 1.3 oz ai/acre in
the first two applications and at 2.0 oz ai/acre in the last two
applications. All four micro-rate applications
included UpBeet at 0.08 oz ai/acre (excluding treatments where UpBeet was
omitted), Stinger at 0.5 oz ai/acre, and a methylated seed oil (MSO) at 1.5
percent v/v.
Sugar beet injury was evaluated May 10
and June 9 and weed control was evaluated 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
Postemergence herbicides were very effective this year. Kochia control was greater than 98 percent
with either the standard rate or micro-rate treatments containing UpBeet
regardless of whether preemergence Nortron was applied (Table 1). Removing UpBeet from the standard rate and
the micro-rate resulted in a respective 18 and 58 percent decrease in kochia
control on July 17. For the standard
rate treatments without UpBeet, the addition of Nortron at any rate provided
kochia control similar to the standard rate with UpBeet. For micro-rate treatments without UpBeet,
the addition of preemergence Nortron, regardless of the rate, did not control
kochia as well as the micro-rate with UpBeet.
Increasing Nortron rates increased kochia control. Pigweed control also was reduced when UpBeet
was omitted from the micro-rate. The
addition of Nortron at 16 or 24 oz ai/acre improved kochia control, but the 32-
or 48- oz ai/acre rates were required to control kochia equal to the micro-rate
with UpBeet. There were no differences
among treatments for common lambsquarters, hairy nightshade, or barnyardgrass
control. Common lambsquarters and hairy
nightshade control was 98 percent or higher while barnyardgrass control ranged
from 87 to 99 percent.
Injury on May 10 was significantly higher for standard rate
treatments with UpBeet compared to standard rate treatments without UpBeet or
compared to any of the micro-rate treatments (Table 2). Within the micro-rate treatments, the 48- oz
ai/acre rate of Nortron caused greater injury (23 vs 5-14 percent) than any of
the other micro-rate treatments with or without Nortron preemergence. On June 9, injury was similar among all
treatments. Sugar beet yields were not significantly
different among any of the standard rate treatments. Sugar beet yields were lowest with the micro-rate applied without
UpBeet. The addition of preemergence
Nortron at 32 oz ai/acre to the micro-rate without UpBeet was the only
treatment that produced yields similar to the micro-rate with UpBeet. The lower Nortron rates had lower yields and
the 48- oz ai/acre Nortron treatment also yielded less than the micro-rate with
UpBeet. The lower yield with the high
rate of Nortron may have been related to the increased sugar beet injury.
In areas where kochia has become resistant to UpBeet, a
preemergence application of Nortron followed by postemergence herbicides at
standard rates should provide effective control. Removing UpBeet from the spray mixture may not be advisable since
UpBeet would still be effective in controlling non-UpBeet-resistant kochia and
also helps control other weeds. The
micro-rate should not be used in areas with UpBeet resistant kochia because
even with high rates of preemergence Nortron, acceptable kochia control cannot
be achieved.
Table 1. Kochia control with preemergence Nortron® in standard and micro-rate herbicide programs, Malheur
Experiment Station, Oregon State University, Ontario, OR, 2004.
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Weed control |
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Kochia |
Pigweed‡ spp. |
Lambs- quarters |
Hairy nightshade |
Barnyard- grass |
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Treatment* |
Rate |
Timing† |
7-27 |
9-3 |
7-27 |
7-27 |
7-27 |
7-27 |
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|
oz ai/acre & % v/v |
|
----------------------------------- %--------------------------------------- |
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Untreated control |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
||
|
Standard Rate Program Progress + UpBeet Progress + UpBeet +
Stinger Progress + UpBeet + Stinger |
4.0 + 0.25 5.4 + 0.25 + 1.5 6.7 + 0.25 + 1.5 |
3 5 6 |
100 |
100 |
100 |
100 |
99 |
95 |
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Micro-Rate Program Progress + UpBeet +
Stinger + MSO Progress + UpBeet +
Stinger + MSO |
1.3 + 0.083 + 0.5 + 1.5% v/v 2.0 + 0.083 + 0.5 + 1.5% v/v |
2,4 7,8 |
98 |
98 |
97 |
100 |
100 |
97 |
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Nortron fb Standard with
Upbeet |
16.0 --- |
1 3,5,6 |
100 |
100 |
99 |
100 |
100 |
97 |
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Nortron fb Standard with UpBeet |
24.0 --- |
1 3,5,6 |
100 |
100 |
100 |
100 |
100 |
98 |
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Nortron fb Standard with UpBeet |
32.0 --- |
1 3,5,6 |
100 |
100 |
100 |
100 |
100 |
99 |
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Nortron fb Standard w/out UpBeet |
16.0 --- |
1 3,5,6 |
100 |
100 |
100 |
100 |
100 |
93 |
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Nortron fb Standard w/out UpBeet |
24.0 --- |
1 3,5,6 |
94 |
96 |
98 |
100 |
100 |
93 |
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Nortron fb Standard w/out UpBeet |
32.0 --- |
1 3,5,6 |
98 |
98 |
100 |
100 |
100 |
97 |
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Nortron fb Micro with UpBeet |
16.0 --- |
1 2,4,7,8 |
100 |
100 |
100 |
99 |
100 |
91 |
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Nortron fb Micro with UpBeet |
24.0 --- |
1 2,4,7,8 |
99 |
99 |
100 |
100 |
100 |
97 |
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Nortron fb Micro with UpBeet |
32.0 --- |
1 |
100 |
100 |
100 |
100 |
100 |
95 |
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Nortron fb Micro w/out UpBeet |
16.0 --- |
1 2,4,7,8 |
62 |
58 |
91 |
100 |
100 |
93 |
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Nortron fb Micro w/out UpBeet |
24.0 --- |
1 2,4,7,8 |
66 |
65 |
91 |
100 |
100 |
92 |
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Nortron fb Micro w/out UpBeet |
32.0 --- |
1 2,4,7,8 |
75 |
73 |
98 |
100 |
100 |
92 |
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Standard w/out UpBeet |
--- |
3,5,6 |
82 |
88 |
95 |
100 |
100 |
95 |
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Micro w/out UpBeet |
--- |
2,4,7,8 |
40 |
48 |
80 |
100 |
100 |
87 |
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Nortron fb Micro w/out UpBeet |
48.0 --- |
1 2,4,7,8 |
84 |
86 |
98 |
98 |
100 |
97 |
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LSD ( 0.05) |
-- |
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8 |
8 |
6 |
NS |
NS |
NS |
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*fb = Followed by.
†Application
timings were (1) April 13 preemergence, (2) April 23 to cotyledon beets, (3)
April 26 to full cotyledon beets, (4) April 30 to 2-leaf beets, (5) May 3 to 2-
to 4-leaf beets, (6) May 14 to 6- to 8-leaf beets, (7) May 15 to 8- to 10-leaf
beets, and (8) May 20 to 8- to 12-leaf beets.
‡Pigweed species included Powell amaranth and redroot
pigweed.
Table 2. Sugar beet
injury and yield with preemergence Nortron® in standard and micro-rate herbicide programs, 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 |
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Root yield |
Sucrose |
Extraction |
ERS§ |
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|
oz ai/acre and % v/v |
|
------- % ------- |
|
ton/acre |
------------ % ------------ |
lbs/acre |
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Untreated control |
-- |
-- |
-- |
-- |
|
6.1 |
16.6 |
93.5 |
1,958 |
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Standard Rate Program Progress + UpBeet Progress + UpBeet +
Stinger Progress + UpBeet + Stinger |
4.0 + 0.25 5.4 + 0.25 + 1.5 6.7 + 0.25 + 1.5 |
3 5 6 |
33 |
21 |
|
41.1 |
16.7 |
93.6 |
12,802 |
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Micro-Rate Program Progress + UpBeet +
Stinger + MSO Progress + UpBeet +
Stinger + MSO |
1.3 + 0.083 + 0.5 + 1.5% v/v 2.0 + 0.083 + 0.5 + 1.5% v/v |
2,4 7,8 |
9 |
9 |
|
44.3 |
16.5 |
93.0 |
13,614 |
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Nortron fb Standard with
UpBeet |
16.0 --- |
1 3,5,6 |
30 |
18 |
|
42.7 |
17.1 |
93.4 |
13,616 |
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Nortron fb Standard with UpBeet |
24.0 --- |
1 3,5,6 |
30 |
15 |
|
39.8 |
17.1 |
93.2 |
12,653 |
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Nortron fb Standard with UpBeet |
32.0 --- |
1 3,5,6 |
32 |
20 |
|
40.9 |
16.9 |
93.3 |
12,940 |
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Nortron fb Standard w/out UpBeet |
16.0 --- |
1 3,5,6 |
13 |
11 |
|
40.6 |
16.9 |
93.1 |
12,770 |
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Nortron fb Standard w/out UpBeet |
24.0 --- |
1 3,5,6 |
15 |
21 |
|
39.6 |
16.4 |
93.0 |
12,067 |
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Nortron fb Standard w/out UpBeet |
32.0 --- |
1 3,5,6 |
18 |
14 |
|
42.1 |
16.1 |
93.9 |
12,613 |
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Nortron fb Micro with UpBeet |
16.0 --- |
1 2,4,7,8 |
11 |
18 |
|
42.2 |
16.5 |
93.7 |
13,025 |
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Nortron fb Micro with UpBeet |
24.0 --- |
1 2,4,7,8 |
10 |
11 |
|
42.2 |
16.3 |
93.1 |
12,792 |
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Nortron fb Micro with UpBeet |
32.0 --- |
1 |
13 |
14 |
|
40.5 |
17.1 |
93.5 |
12,918 |
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Nortron fb Micro w/out UpBeet |
16.0 --- |
1 2,4,7,8 |
11 |
18 |
|
29.4 |
17.4 |
93.3 |
9,509 |
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Nortron fb Micro w/out UpBeet |
24.0 --- |
1 2,4,7,8 |
14 |
15 |
|
34.5 |
17.6 |
93.6 |
11,386 |
|
Nortron fb Micro w/out UpBeet |
32.0 --- |
1 2,4,7,8 |
5 |
13 |
|
38.0 |
17.3 |
93.5 |
12,300 |
|
Standard w/out UpBeet |
--- |
3,5,6 |
19 |
13 |
|
38.8 |
17.0 |
93.4 |
12,345 |
|
Micro w/out UpBeet |
--- |
2,4,7,8 |
6 |
6 |
|
29.3 |
17.7 |
93.9 |
9,786 |
|
Nortron fb Micro w/out UpBeet |
48.0 --- |
1 2,4,7,8 |
23 |
26 |
|
35.2 |
17.5 |
93.4 |
11,490 |
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LSD (0.05) |
-- |
|
8 |
13 |
|
6.1 |
0.8 |
NS |
1,937 |
*fb = Followed by
†Application
timings were (1) April 13 preemergence, (2) April 23 to cotyledon beets, (3)
April 26 to full cotyledon beets, (4) April 30 to 2-leaf beets, (5) May 3 to 2
to 4-leaf beets, (6) May 14 to 6 to 8-leaf beets, (7) May 15 to 8 to 10-leaf
beets, and (8) May 20 to 8 to 12-leaf beets.
‡Sugar beets were harvested October 8 and 9.
§ERS = estimated recoverable sucrose.
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