EVALUATION OF HERBICIDES FOR WEED CONTROL

IN IRRIGATED FIELD CORN

Joel Felix and J. Ishida

Malheur Experiment Station

Oregon State University

Ontario, OR, 2008

Introduction

A large portion of the United States' corn acreage is planted to Roundup Ready® hybrids with Roundup® being the herbicide of choice for weed management. In 2007, Malheur County planted 24,900 acres of corn, which was about 42 percent of the total corn acreage in the state of Oregon (USDA NASS 2007). Laudis® (Tembotrione) is a new herbicide marketed by Bayer CropScience for annual broadleaf and grass weed control in corn. Laudis is registered for use on field, silage, and seed corn as well as sweet corn and popcorn. The introduction of Laudis provides growers with a tool to control weeds with resistance to other herbicides and weeds that are difficult to control in glyphosate-based programs. Also, a new herbicide from BASF Corporation, BAS 87102H (Kixor), was evaluated for possible stand-alone applications when applied preplant or mixed with glyphosate for improved and complete burndown of more than 80 broadleaf weeds, including those resistant to glyphosate and ALS herbicides. The objective of this study was to evaluate Laudis and BAS 78102H herbicide performance under local conditions.

Materials and Methods

A field study was established in 2008 at the Malheur Experiment Station near Ontario, Oregon, in a well-drained furrow-irrigated field previously planted to wheat. The study area was moldboard plowed, disked, and bedded on 30-inch spacing on April 15, 2008. The predominant soil was an Owyhee silt loam with 1.9 percent organic matter, a pH of 7.1, and a cation exchange capacity of 11 meq/g of soil. The study was laid out in a randomized complete block design with four replications. Individual plots were 10 ft wide (4 rows) by 25 ft long. Roundup Ready corn hybrid 'DK C52-59-RR' was planted with a John Deere model 71 flexi planter on May 6, at 7⅞-inch spacing within the row.Corn plants were fertilized on June 17 at the rate of 180, 20, and 3 lb/acre nitrogen (N), potassium (K), and zinc (Zn), respectively. The study was furrow irrigated on a calendar schedule to maintain moisture in the top 12 inches of the soil profile starting May 7. Pre-emergence (PRE) herbicide treatments were applied on May 10 and post-emergence (POST) on June 9, 2008. All herbicide treatments were applied using a CO2-pressurized backpack sprayer with a boom fitted with 6 Teejet nozzles calibrated to deliver 20 gal/acre at 40 psi and 3 mph. Plots were visually evaluated for crop phytotoxicity and weed control using 0-100 percent scale (where 0 = no crop injury or no weed control and 100 = complete crop kill or complete weed control) at 6, 24, 35, and 65 days after treatment (DAT). Treatment performance and yield data are presented in Tables 1-4. Corn ears were hand picked from the two (25 ft long) center rows on October 9, 2008. The data were subjected to analysis of variance and means separated using the least significant difference (LSD) at P = 0.05.

Results and Discussion

There was no visible corn injury attributable to any of the herbicide treatments. Visual evaluations 6 days after POST herbicide application indicated kochia control ranging from 89 to 99 percent (Table 1). Control of common lambsquarters, pigweed species, common barnyardgrass, hairy nightshade, and prickly lettuce ranged from 50 to 99 percent, 87 to 99 percent, 90 to 99 percent, 83 to 99 percent, and 95 to 99 percent, respectively, across herbicide treatments. At 24 DAT, control for kochia, common barnyardgrass, hairy nightshade, and prickly lettuce was 99 percent (Table 2). Control for common lambsquarters and pigweed species ranged between 75 and 99 percent across herbicide treatments. Kochia and prickly lettuce control remained at 99 percent for observations taken 35 DAT (Table 3). Common lambsquarters control ranged from 49 to 99 percent while that for pigweed species was 51 to 99 percent at 35 DAT. Visual control ratings for common barnyardgrass and hairy nightshade ranged from 89 to 99 percent and 95 to 99 percent, respectively. Weed control at 65 DAT was 90 percent or greater except for BAS 78102H applied PRE at 13 fl oz/acre plus glyphosate at 22 fl oz/acre that had control ranging from 49 to 99 percent across weed species (Table 4). Corn yield was similar across herbicide treatments (272 to 285 bu/acre) and lowest in the untreated control (236 bu/acre). Even though use of both Laudis and BAS 78102H in glyphosate tank mixtures did not improve corn yield, they provided an opportunity to manage hard to control weeds in total glyphosate programs and avoid selection for resistant biotypes.

References

USDA National Agricultural Statistics Services. 2007. http://www.nass.usda.gov/Data_and_Statistics/County_Data_Files/Release_Schedule/index.asp Accessed December 8, 2008.


Table 1. Weed control in Roundup Ready® field corn with Laudis® and Kixor (BAS78102H) at 6 days (6/14/2008) after post-emergence herbicide application at Malheur Experiment Station, Oregon State University, Ontario, OR, 2008.

Weed control

Treatment name

Rate

Unit

Timinga

Corn injury

Kochia

Common lambsquarters

Pigweed speciesb

Common barnyardgrass

Hairy nightshade

Prickly lettuce

(%)

------------------------------------------------------- % --------------------------------------------------------

Untreated

0.0

ac

0.0

d

0.0

e

0.0

d

0.0

c

0.0

d

0.0

c

Laudis

3.0

fl oz/acre

POST

0.0

a

88.8

c

88.8

bc

97.0

ab

89.5

b

97.0

a

99.0

a

Atrazine

8

oz/acre

POST

MSOd

8

pt/100gal

POST

Ammonium Sulfate

2.5

gal/100gal

POST

Laudis

3.0

oz/acre

POST

0.0

a

92.0

bc

85.0

c

97.0

ab

94.5

ab

82.5

c

99.0

a

Atrazine

4

oz/acre

POST

MSO

8

pt/100gal

POST

Ammonium Sulfate

2.5

gal/100gal

POST

Outlook

14

oz/acre

PRE

0.0

a

92.0

bc

55.0

d

90.0

bc

99.0

a

99.0

a

99.0

a

Laudis

3.0

oz/acre

POST

MSO

8

pt/100gal

POST

Ammonium Sulfate

2.5

gal/100gal

POST

Laudis

3.0

oz/acre

POST

0.0

a

99.0

a

82.5

c

87.0

c

89.5

b

87.5

bc

94.8

b

Status

2.5

oz/acre

POST

MSO

8

pt/100gal

POST

Ammonium Sulfate

2.5

gal/100gal

POST

Roundup Powermax

22

oz/acre

POST

0.0

a

94.5

ab

94.5

ab

99.0

a

94.5

ab

92.5

ab

99.0

a

Laudis

3.0

oz/acre

POST

Ammonium Sulfate

2.5

gal/100 gal

POST

Roundup Powermax

22

oz/acre

POST

0.0

a

99.0

a

99.0

a

99.0

a

99.0

a

99.0

a

99.0

a

Ammonium Sulfate

8.2

pt/100 gal

POST

Roundup Powermax

22

oz/acre

LATEPOST

Ammonium Sulfate

2.5

gal/100 gal

LATEPOST

BAS 78102H

13

fl oz/acre

PRE

0.0

a

99.0

a

50.0

d

87.5

c

99.0

a

97.0

a

99.0

a

MSO

1.6

pt/acre

Ammonium Sulfate

2.5

gal/100gal

Roundup Powermax

22

fl oz/acre

BAS 78102H

16

fl oz/acre

PRE

0.0

a

99.0

a

99.0

a

99.0

a

99.0

a

99.0

a

99.0

a

MSO

1.6

pt/acre

Ammonium Sulfate

2.5

gal/100gal

Roundup Powermax

22

fl oz/acre

Roundup Powermax

22

fl oz/acre

POST

Non-ionic surfactant

5

gal/100gal

Ammonium Sulfate

2

pt/100gal

Prowl H2O

1.8

pt/acre

PRE

0.0

a

99.0

a

99.0

a

99.0

a

99.0

a

99.0

a

99.0

a

Outlook

14.0

oz/acre

Roundup Powermax

22

fl oz/acre

POST

Non-ionic surfactant

2

pt/100gal

Ammonium Sulfate

5

gal/100gal












































a PRE = Pre-weed emergence treatments applied May 10, 2008; POST = Post-emergence treatments applied on June 9, 2008; LATEPOST applied June 18, 2008.

b Pigweed species = red root pigweed and Powell amaranth.

cMeans within a column followed by the same letter do not significantly differ (LSD, P = 0.05).

dMSO = methylated seed oil.


Table 2. Weed control in Roundup Ready® field corn with Laudis® and Kixor (BAS78102H) at 24 days (7/3/2008) after post-emergence herbicide application at Malheur Experiment Station, Oregon State University, Ontario, OR, 2008.

Weed control

Treatment name

Rate

Rate unit

Timinga

Corn

injury

Kochia

Common lambsquarters

Pigweed speciesb

Common barnyardgrass

Hairy nightshade

Prickly lettuce

(%)

------------------------------------------------------- % --------------------------------------------------------

Untreated

0.0

ac

0.0

b

0.0

e

0.0

e

0.0

b

0.0

b

0.0

b

Laudis

3.0

fl oz/acre

POST

0.0

a

99.0

a

99.0

a

99.0

a

99.0

a

99.0

a

99.0

a

Atrazine

8

oz/acre

POST

MSOd

8

pt/100gal

POST

Ammonium Sulfate

2.5

gal/100gal

POST

Laudis

3.0

oz/acre

POST

0.0

a

99.0

a

99.0

a

99.0

a

99.0

a

99.0

a

99.0

a

Atrazine

4

oz/acre

POST

MSO

8

pt/100gal

POST

Ammonium Sulfate

2.5

gal/100gal

POST

Outlook

14

oz/acre

PRE

0.0

a

99.0

a

99.0

a

99.0

a

99.0

a

99.0

a

99.0

a

Laudis

3.0

oz/acre

POST

MSO

8

pt/100gal

POST

Ammonium Sulfate

2.5

gal/100gal

POST

Laudis

3.0

oz/acre

POST

0.0

a

99.0

a

99.0

a

99.0

a

99.0

a

99.0

a

99.0

a

Status

2.5

oz/acre

POST

MSO

8

pt/100gal

POST

Ammonium Sulfate

2.5

gal/100gal

POST

Roundup Powermax

22

oz/acre

POST

0.0

a

99.0

a

95.0

b

95.0

b

99.0

a

99.0

a

99.0

a

Laudis

3.0

oz/acre

POST

Ammonium Sulfate

2.5

gal/100 gal

POST

Roundup Powermax

22

oz/acre

POST

0.0

a

99.0

a

90.0

c

90.0

c

99.0

a

99.0

a

99.0

a

Ammonium Sulfate

8.2

pt/100 gal

POST

Roundup Powermax

22

oz/acre

LATEPOST

Ammonium Sulfate

2.5

gal/100 gal

LATEPOST

BAS 78102H

13

fl oz/acre

PRE

0.0

a

99.0

a

75.0

d

75.0

d

99.0

a

99.0

a

99.0

a

MSO

1.6

pt/acre

Ammonium Sulfate

2.5

gal/100gal

Roundup Powermax

22

fl oz/acre

BAS 78102H

16

fl oz/acre

PRE

0.0

a

99.0

a

99.0

a

99.0

a

99.0

a

99.0

a

99.0

a

MSO

1.6

pt/acre

Ammonium Sulfate

2.5

gal/100gal

Roundup Powermax

22

fl oz/acre

Roundup Powermax

22

fl oz/acre

POST

Non-ionic surfactant

5

gal/100gal

Ammonium Sulfate

2

pt/100gal

Prowl H2O

1.8

pt/acre

PRE

0.0

a

99.0

a

99.0

a

99.0

a

99.0

a

99.0

a

99.0

a

Outlook

14.0

oz/acre

Roundup Powermax

22

fl oz/acre

POST

Non-ionic surfactant

2

pt/100gal

Ammonium Sulfate

5

gal/100gal












































a PRE = Pre-weed emergence treatments applied May 10, 2008; POST = Post-emergence treatments applied on June 9, 2008; LATEPOST applied June 18, 2008.

b Pigweed species = red root pigweed and Powell amaranth.

cMeans within a column followed by the same letter do not significantly differ (LSD, P = 0.05).

dMSO = methylated seed oil.


Table 3. Weed control in Roundup Ready® field corn with Laudis® and Kixor (BAS78102H) at 35 days (7/14/2008) after post-emergence herbicide application at Malheur Experiment Station, Oregon State University, Ontario, OR, 2008.

Weed control

Treatment name

Rate

Rate unit

Timinga

Corn

Kochia

Common lambsquarters

Pigweed speciesb

Common barnyardgrass

Hairy nightshade

Prickly lettuce

Injury (%)

------------------------------------------------------- % --------------------------------------------------------

Untreated

0.0

ac

0.0

b

0.0

f

0.0

e

0.0

d

0.0

d

0.0

b

Laudis

3.0

fl oz/acre

POST

0.0

a

99.0

a

99.0

a

99.0

a

99.0

a

99.0

a

99.0

a

Atrazine

8

oz/acre

POST

MSOd

8

pt/100gal

POST

Ammonium Sulfate

2.5

gal/100gal

POST

Laudis

3.0

oz/acre

POST

0.0

a

99.0

a

99.0

a

99.0

a

99.0

a

99.0

a

99.0

a

Atrazine

4

oz/acre

POST

MSO

8

pt/100gal

POST

Ammonium Sulfate

2.5

gal/100gal

POST

Outlook

14

oz/acre

PRE

0.0

a

99.0

a

99.0

a

99.0

a

99.0

a

99.0

a

99.0

a

Laudis

3.0

oz/acre

POST

MSO

8

pt/100gal

POST

Ammonium Sulfate

2.5

gal/100gal

POST

Laudis

3.0

oz/acre

POST

0.0

a

99.0

a

92.5

c

93.8

b

95.0

b

95.0

b

99.0

a

Status

2.5

oz/acre

POST

MSO

8

pt/100gal

POST

Ammonium Sulfate

2.5

gal/100gal

POST

Roundup Powermax

22

oz/acre

POST

0.0

a

99.0

a

92.5

c

93.8

b

95.0

b

95.0

b

99.0

a

Laudis

3.0

oz/acre

POST

Ammonium Sulfate

2.5

gal/100 gal

POST

Roundup Powermax

22

oz/acre

POST

0.0

a

99.0

a

90.0

d

91.3

c

99.0

a

90.0

c

99.0

a

Ammonium Sulfate

8.2

pt/100 gal

POST

Roundup Powermax

22

oz/acre

LATEPOST

Ammonium Sulfate

2.5

gal/100 gal

LATEPOST

BAS 78102H

13

fl oz/acre

PRE

0.0

a

99.0

a

48.8

e

51.3

d

88.8

c

90.0

c

99.0

a

MSO

1.6

pt/acre

Ammonium Sulfate

2.5

gal/100gal

Roundup Powermax

22

fl oz/acre

BAS 78102H

16

fl oz/acre

PRE

0.0

a

99.0

a

95.0

b

95.0

b

99.0

a

95.0

b

99.0

a

MSO

1.6

pt/acre

Ammonium Sulfate

2.5

gal/100gal

Roundup Powermax

22

fl oz/acre

Roundup Powermax

22

fl oz/acre

POST

Non-ionic surfactant

5

gal/100gal

Ammonium Sulfate

2

pt/100gal

Prowl H2O

1.8

pt/acre

PRE

0.0

a

99.0

a

99.0

a

99.0

a

99.0

a

99.0

a

99.0

a

Outlook

14.0

oz/acre

Roundup Powermax

22

fl oz/acre

POST

Non-ionic surfactant

2

pt/100gal

Ammonium Sulfate

5

gal/100gal












































a PRE = Pre-weed emergence treatments applied May 10, 2008; POST = Post-emergence treatments applied on June 9, 2008; LATEPOST applied June 18, 2008.

b Pigweed species = red root pigweed and Powell amaranth.

cMeans within a column followed by the same letter do not significantly differ (LSD, P = 0.05).

dMSO = methylated seed oil.


Table 4. Weed control in Roundup Ready® field corn with Laudis® and Kixor (BAS78102H) at 65 days (8/14/2008) after post-emergence herbicide application and corn yield at Malheur Experiment Station, Oregon State University, Ontario, OR, 2008.

Weed control

Treatment name

Rate

Rate Unit

Timinga

Corn

Kochia

Common lambsquarters

Pigweed speciesb

Common barnyardgrass

Hairy nightshade

Prickly lettuce

Corn Yield

Injury (%)

------------------------------------------------------ % --------------------------------------------------

Bu/Acre

Untreated

0.0

ac

0.0

b

0.0

e

0.0

e

0.0

d

0.0

d

0.0

b

235.8

b

Laudis

3.0

fl oz/acre

POST

0.0

a

99.0

a

99.0

a

99.0

a

99.0

a

99.0

a

99.0

a

282.9

a

Atrazine

8

oz/acre

POST

MSO

8

pt/100gal

POST

Ammonium Sulfate

2.5

gal/100gal

POST

Laudis

3.0

oz/acre

POST

0.0

a

99.0

a

99.0

a

99.0

a

99.0

a

99.0

a

99.0

a

280.3

a

Atrazine

4

oz/acre

POST

MSO

8

pt/100gal

POST

Ammonium Sulfate

2.5

gal/100gal

POST

Outlook

14

oz/acre

PRE

0.0

a

99.0

a

99.0

a

99.0

a

99.0

a

99.0

a

99.0

a

284.9

a

Laudis

3.0

oz/acre

POST

MSO

8

pt/100gal

POST

Ammonium Sulfate

2.5

gal/100gal

POST

Laudis

3.0

oz/acre

POST

0.0

a

99.0

a

90.0

c

90.0

c

90.0

b

90.0

c

99.0

a

271.9

a

Status

2.5

oz/acre

POST

MSO

8

pt/100gal

POST

Ammonium Sulfate

2.5

gal/100gal

POST

Roundup Powermax

22

oz/acre

POST

0.0

a

99.0

a

90.0

c

90.0

c

90.0

b

90.0

c

99.0

a

272.9

a

Laudis

3.0

oz/acre

POST

Ammonium Sulfate

2.5

gal/100 gal

POST

Roundup Powermax

22

oz/acre

POST

0.0

a

99.0

a

90.0

c

91.3

c

99.0

a

90.0

c

99.0

a

272.9

a

Ammonium Sulfate

8.2

pt/100 gal

POST

Roundup Powermax

22

oz/acre

LATEPOST

Ammonium Sulfate

2.5

gal/100 gal

LATEPOST

BAS 78102H

13

fl oz/acre

PRE

0.0

a

99.0

a

48.8

d

51.3

d

88.8

c

90.0

c

99.0

a

270.6

a

MSO

1.6

pt/acre

Ammonium Sulfate

2.5

gal/100gal

Roundup Powermax

22

fl oz/acre

BAS 78102H

16

fl oz/acre

PRE

0.0

a

99.0

a

93.8

b

93.8

b

99.0

a

95.0

b

99.0

a

273.8

a

MSO

1.6

pt/acre

Ammonium Sulfate

2.5

gal/100gal

Roundup Powermax

22

fl oz/acre

Roundup Powermax

22

fl oz/acre

POST

Non-ionic surfactant

5

gal/100gal

Ammonium Sulfate

2

pt/100gal

Prowl H2O

1.8

pt/acre

PRE

0.0

a

99.0

a

99.0

a

99.0

a

99.0

a

99.0

a

99.0

a

285.3

a

Outlook

14.0

oz/acre

Roundup Powermax

22

fl oz/acre

POST

Non-ionic surfactant

2

pt/100gal

Ammonium Sulfate

5

gal/100gal



































a PRE = Pre-weed emergence treatments applied May 10, 2008; POST = Post-emergence treatments applied on June 9, 2008; LATEPOST applied June 18, 2008.

b Pigweed species = red root pigweed and Powell amaranth.

cMeans within a column followed by the same letter do not significantly differ (LSD, P = 0.05).

dMSO = methylated seed oil.