Malheur Experiment Station

Information for Sustainable Agriculture

TIMING OF OUTLOOK^® AND 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

Outlook (dimethenamid-P) and Dual Magnum (s-metolachlor) are soil-active herbicides that are labeled for postemergence application in sugar beet. Outlook can be applied to two-leaf or larger beets and Dual Magnum may be applied to one-leaf or larger beets. Outlook or Dual Magnum were applied as part of a standard rate program in the second or third postemergence application or as a lay-by application. The objectives of this trial were 1) to determine if weed control can be improved with Outlook or Dual Magnum in the standard rate program, and 2) to 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 4, 2003. Sugar beets (Hilleshog 'PM-21') were planted in 22-inch rows at a 2-inch seed spacing. On April 3, kochia, pigweed, and common lambsquarters seed was spread over the entire experimental area to promote an even weed distribution. After planting, 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 13 and 14. Plots were sidedressed on June 3 with 176 lb nitrogen (urea), 96 lb phosphate, 100 lb potash, 38 lb sulfates, 62 lb elemental sulfur, 2 lb zinc, and 1 lb/acre boron. All plots were treated with Roundup (0.75 lb ai/acre) prior to sugar beet emergence on April 11. On May 16, Temik 15G (14 lb/acre) was applied for sugar beet root maggot control. For powdery mildew control, Headline (12 fl oz/acre) was applied on June 17 and again on July 2 with Super Six liquid sulfur (16 pt/acre), Topsin M (0.5 lb/acre) was applied on August 4. 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 four rows wide and 27 ft long and treatments were arranged in a randomized complete block design with four replicates.

Soil-active herbicides 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 with the selected herbicides. The standard rate program consisted of Progress (ethofumesate + desmedipham + phenmedipham) applied at 4.0, 5.4, and 6.7 oz ai/acre in applications one, two, and three, respectively. UpBeet (triflusulfuron) was applied at 0.25 oz ai/acre in all three applications and Stinger (clopyralid) at 1.5 oz ai/acre in the last two applications. Soil-active herbicides included Outlook, Dual Magnum, and Treflan (trifluralin). Outlook was applied at 12.0 oz ai/acre when applied in the second or third application or as a lay-by following the last cultivation. When split across the first and second applications, Outlook was applied at 10.5 and 5.2 oz ai/acre, respectively. Treflan at 6 oz ai/acre was applied with Outlook as a lay-by. Dual Magnum was applied at 20.8 oz ai/acre in the second or third application or as a lay-by. The first, second, third, and lay-by applications were made on April 23, April 30, May 16, and May 21, to cotyledon, 2-leaf, 10-leaf, and 12-leaf beets, respectively.

Sugar beet injury and weed control were evaluated throughout the season. Sugar beet yields were determined by harvesting the center two rows of each plot on October 6 and 7. 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 Hilleshog Mono-Hy 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

Outlook or Dual Magnum, when added to the standard rate program whether applied in the second or third application or as a lay-by application, did not improve broadleaf weed control compared to the standard rate treatment without any soil-active herbicides (Table 1). All treatments resulted in 97 percent or greater control of broadleaf weed species. Treatments including Outlook or Dual Magnum, regardless of when they were applied, controlled barnyardgrass significantly better than the standard rate treatment without a soil-active herbicide application. Barnyardgrass control was greater with Outlook compared to Dual Magnum when applied in the third standard rate application. Control of barnyardgrass with Outlook was similar whether applied in the second, third, or lay-by applications. Control of barnyardgrass with Dual Magnum was greater when applied in the second application than when applied in the third or lay-by applications.

Sugar beet injury on May 5 was greater with treatments where Outlook or Dual Magnum were applied in the second application compared to the standard treatment alone (Table 2). Injury on May 5, which was only 4 days after the third standard rate application, was similar between treatments with Outlook or Dual Magnum in the third application and the standard treatment without Outlook or Dual Magnum. There were no differences in sugar beet injury among treatments on June 2 (17 days after treatment). Sugar beet root yields associated with herbicide treatments ranged from 47.7 to 49.5 tons/acre and were significantly greater than the untreated control (Table 2). Estimated recoverable sucrose yields were similar among herbicide treatments and were greater than the untreated control.

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, 2003.

Weed control^†

Kochia Pigweed
spp.^‡
Lambs-
quarters
Hairy
nightshade
Barnyard-
grass

Treatment
Rate Timing* 8-5 8-5 8-5 8-5 6-16

oz ai/acre
--------------------------------------- % ---------------------------------------

Untreated control
-- -- -- -- -- -- --

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
97 98 100 100 81

Progress + UpBeet
Progress + UpBeet + Stinger +
Outlook
Progress + UpBeet + Stinger
4.0 + 0.25
5.4 + 0.25 + 1.5
12.0
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 +
12.0
1
2
3
98 92 100 100 99

Progress + UpBeet
Progress + UpBeet + Stinger +
Outlook
Progress + UpBeet + Stinger +
Outlook
4.0 + 0.25
5.4 + 0.25 + 1.5 +
10.5
6.7 + 0.5 + 1.5 +
5.2
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 + 0.5 + 1.5
12.0
1
2
3
4
98 98 100 100 96

Progress + UpBeet
Progress + UpBeet + Stinger
Progress + UpBeet + Stinger
Outlook + Treflan
4.0 + 0.25
5.4 + 0.25 + 1.5
6.7 + 0.25 + 1.5
12.0 + 6.0
1
2
3
4
98 99 100 100 99

Progress + UpBeet
Progress + UpBeet + Stinger +
Dual Magnum
Progress + UpBeet + Stinger
4.0 + 0.25
5.4 + 0.25 + 1.5 +
20.8
6.7 + 0.25 + 1.5
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 +
20.8
1
2
3
99 96 100 100 90

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
20.8
1
2
3
4
100 96 100 100 93

LSD (0.05)
-- -- NS NS NS NS 5

*Application timings were (1) April 23 to cotyledon beets, (2) April 30 to 2-leaf beets, (3) May 16 to 10-leaf beets, (4) May 21 lay-by to 12-leaf beets. ^†The untreated control was not included in the weed control analysis. ^‡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, 2003.

Sugar beet

Injury^†
Yield^‡

Treatment
Rate Timing* 5-5 6-2
Root
yield
Sucrose Extraction ERS

oz ai/acre
------ % ------
ton/acre ---------- % ---------- lbs/acre

Untreated control
-- -- -- --
26.2 16.7 92.7 8,095

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
17 14
48.2 15.6 92.6 13,896

Progress + UpBeet
Progress + UpBeet + Stinger +
Outlook
Progress + UpBeet + Stinger
4.0 + 0.25
5.4 + 0.25 + 1.5
12.0
6.7 + 0.25 + 1.5
1
2
3
22 19
49.5 15.7 92.9 14,407

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 +
12.0
1
2
3
18 25
47.7 15.6 92.7 13,773

Progress + UpBeet
Progress + UpBeet + Stinger +
Outlook
Progress + UpBeet + Stinger +
Outlook
4.0 + 0.25
5.4 + 0.25 + 1.5 +
10.5
6.7 + 0.5 + 1.5 +
5.2
1
2
3
20 22
49.8 15.9 92.5 14,601

Progress + UpBeet
Progress + UpBeet + Stinger
Progress + UpBeet + Stinger Outlook
4.0 + 0.25
5.4 + 0.25 + 1.5
6.7 + 0.5 + 1.5
12.0
1
2
3
4
20 21
48.2 16.1 92.6 14,350

Progress + UpBeet
Progress + UpBeet + Stinger
Progress + UpBeet + Stinger
Outlook + Treflan
4.0 + 0.25
5.4 + 0.25 + 1.5
6.7 + 0.25 + 1.5
12.0 + 6.0
1
2
3
4
15 21
48.4 16.4 92.7 14,699

Progress + UpBeet
Progress + UpBeet + Stinger +
Dual Magnum
Progress + UpBeet + Stinger
4.0 + 0.25
5.4 + 0.25 + 1.5 +
20.8
6.7 + 0.25 + 1.5
1
2
3
22 22
49.1 15.9 92.3 14,424

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 +
20.8
1
2
3
17 21
48.3 15.8 92.2 14,070

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
20.8
1
2
3
4
15 17
49.0 16.4 92.7 14,934

LSD (0.05)

5 NS
4.1 NS NS 1,491

*Application timings were (1) April 23 to cotyledon beets, (2) April 30 to 2-leaf beets, (3) May 16 to 10-leaf beets, (4) May 21 lay-by to 12-leaf beets.
^†The untreated control was not included in the sugar beet injury analysis.
^‡Sugar beets were harvested on October 6-7, 2003.

MES Publications, MES Notice of events, Vegetation,Malheur County, Leslie Gulch,Succor Creek,Owyhee River,Local wildlife,Strawberry Mountain, Eagle Caps

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

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Ontario, OR 97914

(541) 889-2174

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Last updated Wednesday July 7, 2004 .

			Weed control^†
			Kochia	Pigweed spp.^‡	Lambs- quarters	Hairy nightshade	Barnyard- grass
Treatment	Rate	Timing*	8-5	8-5	8-5	8-5	6-16
	oz ai/acre		--------------------------------------- % ---------------------------------------
Untreated control	--	--	--	--	--	--	--

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	97	98	100	100	81

Progress + UpBeet Progress + UpBeet + Stinger + Outlook Progress + UpBeet + Stinger	4.0 + 0.25 5.4 + 0.25 + 1.5 12.0 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 + 12.0	1 2 3	98	92	100	100	99

Progress + UpBeet Progress + UpBeet + Stinger + Outlook Progress + UpBeet + Stinger + Outlook	4.0 + 0.25 5.4 + 0.25 + 1.5 + 10.5 6.7 + 0.5 + 1.5 + 5.2	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 + 0.5 + 1.5 12.0	1 2 3 4	98	98	100	100	96

Progress + UpBeet Progress + UpBeet + Stinger Progress + UpBeet + Stinger Outlook + Treflan	4.0 + 0.25 5.4 + 0.25 + 1.5 6.7 + 0.25 + 1.5 12.0 + 6.0	1 2 3 4	98	99	100	100	99

Progress + UpBeet Progress + UpBeet + Stinger + Dual Magnum Progress + UpBeet + Stinger	4.0 + 0.25 5.4 + 0.25 + 1.5 + 20.8 6.7 + 0.25 + 1.5	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 + 20.8	1 2 3	99	96	100	100	90

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 20.8	1 2 3 4	100	96	100	100	93

LSD (0.05)	--	--	NS	NS	NS	NS	5

			Sugar beet
			Injury^†		Yield^‡
Treatment	Rate	Timing*	5-5	6-2	Root yield	Sucrose	Extraction	ERS
	oz ai/acre		------ % ------		ton/acre	---------- % ----------		lbs/acre
Untreated control	--	--	--	--	26.2	16.7	92.7	8,095

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	17	14	48.2	15.6	92.6	13,896

Progress + UpBeet Progress + UpBeet + Stinger + Outlook Progress + UpBeet + Stinger	4.0 + 0.25 5.4 + 0.25 + 1.5 12.0 6.7 + 0.25 + 1.5	1 2 3	22	19	49.5	15.7	92.9	14,407

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 + 12.0	1 2 3	18	25	47.7	15.6	92.7	13,773

Progress + UpBeet Progress + UpBeet + Stinger + Outlook Progress + UpBeet + Stinger + Outlook	4.0 + 0.25 5.4 + 0.25 + 1.5 + 10.5 6.7 + 0.5 + 1.5 + 5.2	1 2 3	20	22	49.8	15.9	92.5	14,601

Progress + UpBeet Progress + UpBeet + Stinger Progress + UpBeet + Stinger Outlook	4.0 + 0.25 5.4 + 0.25 + 1.5 6.7 + 0.5 + 1.5 12.0	1 2 3 4	20	21	48.2	16.1	92.6	14,350

Progress + UpBeet Progress + UpBeet + Stinger Progress + UpBeet + Stinger Outlook + Treflan	4.0 + 0.25 5.4 + 0.25 + 1.5 6.7 + 0.25 + 1.5 12.0 + 6.0	1 2 3 4	15	21	48.4	16.4	92.7	14,699

Progress + UpBeet Progress + UpBeet + Stinger + Dual Magnum Progress + UpBeet + Stinger	4.0 + 0.25 5.4 + 0.25 + 1.5 + 20.8 6.7 + 0.25 + 1.5	1 2 3	22	22	49.1	15.9	92.3	14,424

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 + 20.8	1 2 3	17	21	48.3	15.8	92.2	14,070

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 20.8	1 2 3 4	15	17	49.0	16.4	92.7	14,934

LSD (0.05)			5	NS	4.1	NS	NS	1,491

TIMING OF OUTLOOK® AND DUAL MAGNUM® APPLICATIONS FOR WEED CONTROL IN SUGAR BEET