Evaluation of V-10142 (Imazosulfuron) for yellow nutsedge

control in potatoes



Joel Felix and Joey Ishida

Malheur Experiment Station

Oregon State University

Ontario, OR, 2007



Introduction

Weeds are a major production problem for potato growers in eastern Oregon and other parts of the world. If not controlled in a timely manner, weeds can reduce tuber yields through direct competition with the crop for light, moisture, and nutrients, and may harbor insects and diseases that affect potatoes. Growers are always looking for newer and better herbicides to control weeds, especially in the earlier part of the growing season when newly emerged potato plants are vulnerable to competition. Products that control yellow nutsedge are especially sought by growers in eastern Oregon where the weed is widely distributed. Control of yellow nutsedge is extremely critical and a major emphasis is to use soil residual herbicides before the weeds emerge and establish to compete with the crop. If left uncontrolled, yellow nutsedge will reduce potato tuber yield and most importantly, it will produce more tubers that help to sustain its distribution in the field. There are reports that yellow nutsedge rhizomes can penetrate potato tubers and lower both yield and quality (Boldt 1976).

The varieties grown for processing in Malheur County, Oregon are mainly 'Ranger Russet', 'Shepody', and 'Russet Burbank'. Potatoes are generally planted in late March in beds formed during the previous fall. All soil-applied herbicides are sprayed and incorporated before potato emergence. The herbicide tested in this study, V-10142, is soil applied but does not require incorporation, and as such will reduce field activities.




Materials and Methods

A field study was established in a grower field planted to Russet Burbank near Adrian, Oregon. The objective was to determine the most efficient rates, timings, and phytotoxicity of V-10142 herbicide when applied to potatoes alone and in combinations with other herbicides. The study was laid out in a randomized complete block design with four replications; individual plots measured 9 ft wide by 30 ft long. The potatoes were planted in 30-inch beds on April 6 and emerged on May 7, 2007. Pre-emergence (PRE) treatments were applied on April 30 using a CO2 sprayer with a boom fitted with four EVS 8002 flat-fan nozzles. There was no incorporation of the herbicides after applications were done. All postemergence (POST) treatments included methylated seed oil (MSO) at 1 percent V/V and were applied on May 24, 2007 when potato seedling height was about 6 inches and yellow nutsedge was about 4 inches high. Evaluations for phytotoxicity and yellow nutsedge control were done at 7, 14, and 46 days after treatment (DAT). Evaluations were based on visual estimates on a 0-100 percent (0 = no crop phytotoxicity or weed control and 100 = total crop injury or excellent weed control). The data were subjected to analysis of variance and means separated using the least significant difference (LSD) at P = 0.05 percent. Potatoes received overhead irrigation to keep the soil moist and were fertilized and sprayed for insect and disease prevention using recommended production practices for the area. Potatoes were harvested at maturity from the center row, graded following USDA standards, and specific gravity was determined.





Results and Discussion

There was no evident potato injury with any of the V-10142 treatments at any of the evaluation dates (Table 1). The best yellow nutsedge control was observed when a sequential application of PRE was followed by a POST application of V-10142. Yellow nutsedge control was low when V-10142 was applied PRE at 6.4 oz/acre. Yellow nutsedge control at the time of potato canopy closure tended to be greater with sequential applications of V-10142 applied PRE and POST than with single applications of V-10142 applied PRE. Control of yellow nutsedge by sequential applications at 21 DAT ranged from 88 to 94 percent and was similar to that provided by the standard herbicide application of Eptam® plus Prowl® H2O plus Dual Magnum® at 4.5 plus 1.58 plus 1.0 pt/acre, respectively. A similar trend was observed for the evaluations at potato row closure (July 9, 2007). With the exception of the lowest rate of V-10142 applied PRE, all herbicide treatments increased the marketable potato tuber yield compared to the untreated control (Table 2). Tuber yields tended to be greater with sequential application of V-10142 PRE followed by POST than PRE alone. The herbicide V-10142 has potential to become a valuable product for yellow nutsedge control in potato.



References

Boldt, P.F. 1976. Factors influencing the selectivity of U-compounds on yellow nutsedge. M. S. Thesis, Cornell University, Ithaca, NY.






Table 1. Potato response to V-10142 herbicide and yellow nutsedge control on June 1 and 7, 2007 at the Malheur Experiment Station, Oregon State University, Ontario, OR.


Potato

Yellow nutsedge

Potato

Yellow nutsedge


---------------------- 6/1/2007 ----------------------

---------------------- 6/7/2007 ----------------------


Chlorosis

Necrosis

Growth reduction

Control

Chlorosis

Necrosis

Growth reduction

Control


Treatmenta

Rate

Timingb

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

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

1

V10142

6.4

oz/acre

PRE

0.0

0.0

0.0

50.0

0.0

0.0

0.0

50.0

2

V10142

8.5

oz/acre

PRE

0.0

0.0

0.0

77.5

0.0

0.0

0.0

78.8

3

V10142

10.7

oz/acre

PRE

0.0

0.0

0.0

70.0

0.0

0.0

0.0

72.5

4

V10142

6.4

oz/acre

PRE

0.0

0.0

0.0

86.3

0.0

0.0

0.0

78.8


V10142

6.4

oz/acre

POST










MSO

1.6

pt/acre

POST









5

V10142

8.5

oz/acre

PRE

0.0

0.0

0.0

90.0

0.0

0.0

0.0

87.5


V10142

8.5

oz/acre

POST










MSO

1.6

pt/acre

POST









6

V10142

10.7

oz/acre

PRE

0.0

0.0

0.0

95.0

0.0

0.0

0.0

90.0


V10142

10.7

oz/acre

POST










MSO

1.6

pt/acre

POST









7

V10142

6.4

oz/acre

PRE

0.0

0.0

0.0

92.5

0.0

0.0

0.0

90.0


D. Magnum

1.0

pt/acre

PRE










V10142

8.5

oz/acre

POST










MSO

1.6

pt/acre

POST









8

Matrix

1.0

oz/acre

PRE

0.0

0.0

0.0

86.3

0.0

0.0

0.0

81.3


D. Magnum

1.0

pt/acre

PRE










Matrix

1.0

oz/acre

POST










MSO

1.6

pt/acre

POST









9

D. Magnum

1.0

pt/acre

PRE

0.0

0.0

0.0

90.0

0.0

0.0

0.0

81.3


Sencor 4

0.38

pt/acre

PRE










V10142

8.5

oz/acre

POST










MSO

1.6

pt/acre

POST









10

D. Magnum

1.0

pt/acre

PRE

0.0

0.0

0.0

93.8

0.0

0.0

0.0

88.8


Sencor 4

0.38

pt/acre

PRE










Matrix

1.0

oz/acre

POST










MSO

1.6

pt/acre

POST









11

Eptam 7E

4.5

pt/acre

PRE

0.0

0.0

0.0

78.8

0.0

0.0

0.0

63.8


Prowl H2O

1.58

pt/acre

PRE










D. Magnum

1.0

pt/acre

PRE









12

untreated




0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

LSD (P = 0.05)

--

--

--

12.35

--

--

--

18.82

Standard Deviation

--

--

--

8.55

--

--

--

13.02

CV

--

--

--

11.28

--

--

--

18.13

aMSO = Methylated seed oil; D. Magnum = Dual Magnum.

bTiming PRE = Pre-emergence, POST = Post-emergence.







Table 1 continued. Potato response to V-10142 herbicide and yellow nutsedge control on June 14 and July 9, 2007 at the Malheur Experiment Station, Oregon State University, Ontario, OR.


-------------------- Potato ----------------------

-------- Yellow nutsedge --------


------------------ 6/14/2007 -------------------

6/14/2007

7/9/2007


Chlorosis

Necrosis

Growth reduction

Control

Control


Treatmenta

Rate


Timingb

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

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

1

V10142

6.4

oz/acre

PRE

0.0

0.0

0.0

55.0

65.0

2

V10142

8.5

oz/acre

PRE

0.0

0.0

0.0

75.0

78.8

3

V10142

10.7

oz/acre

PRE

0.0

0.0

0.0

82.5

86.3

4

V10142

6.4

oz/acre

PRE

0.0

0.0

0.0

88.8

92.5


V10142

6.4

oz/acre

POST







MSO

1.6

pt/acre

POST






5

V10142

8.5

oz/acre

PRE

0.0

0.0

0.0

88.8

90.0


V10142

8.5

oz/acre

POST







MSO

1.6

pt/acre

POST






6

V10142

10.7

oz/acre

PRE

0.0

0.0

0.0

95.0

95.0


V10142

10.7

oz/acre

POST







MSO

1.6

pt/acre

POST






7

V10142

6.4

oz/acre

PRE

0.0

0.0

0.0

95.0

95.0


D. Magnum

1.0

pt/acre

PRE







V10142

8.5

oz/acre

POST







MSO

1.6

pt/acre

POST






8

Matrix

1.0

oz/acre

PRE

0.0

0.0

0.0

87.5

88.8


D. Magnum

1.0

pt/acre

PRE







Matrix

1.0

oz/acre

POST







MSO

1.6

pt/acre

POST






9

D. Magnum

1.0

pt/acre

PRE

0.0

0.0

0.0

93.8

95.0


Sencor 4

0.38

pt/acre

PRE







V10142

8.5

oz/acre

POST







MSO

1.6

pt/acre

POST






10

D. Magnum

1.0

pt/acre

PRE

0.0

0.0

0.0

95.0

95.0


Sencor 4

0.38

pt/acre

PRE







Matrix

1.0

oz/acre

POST







MSO

1.6

pt/acre

POST






11

Eptam 7E

4.5

pt/acre

PRE

0.0

0.0

0.0

95.0

95.0


Prowl H2O

1.58

pt/acre

PRE







D. Magnum

1.0

pt/acre

PRE






12

untreated




0.0

0.0

0.0

0.0

0.0

LSD (P =.05)

--

--

--

10.57

8.81

CV

--

--

--

9.23

7.5

aMSO = Methylated seed oil; D. Magnum = Dual Magnum.

bTiming PRE = Pre-emergence, POST = Post-emergence.








Table 2. Potato tuber yield in response to V-10142 herbicide application to control yellow nutsedge at the Malheur Experiment Station, Oregon State University, Ontario, OR, 2007.


<4oz

4-6oz

6-12oz

>12oz

Marketable

twos

cull



CWT/acre

CWT/acre

CWT/acre

CWT/acre

CWT/acre

CWT/acre

CWT/acre

Specific gravity


---------------------------------------- Potato Tuber Yield ----------------------------------------

g/cm-3


Treatmenta

Rate


Timingb









1

V10142

6.4

oz/acre

PRE

56

54

204

152

411

50

3

1.0738

2

V10142

8.5

oz/acre

PRE

41

57

202

146

406

55

10

1.0698

3

V10142

10.7

oz/acre

PRE

76

65

198

133

396

83

28

1.0715

4

V10142

6.4

oz/acre

PRE

56

62

270

117

409

56

2

1.0785


V10142

6.4

oz/acre

POST










MSOa

1.6

pt/acre

POST









5

V10142

8.5

oz/acre

PRE

68

72

217

147

436

79

13

1.0748


V10142

8.5

oz/acre

POST










MSO

1.6

pt/acre

POST









6

V10142

10.7

oz/acre

PRE

52

75

256

153

483

80

20

1.0828


V10142

10.7

oz/acre

POST










MSO

1.6

pt/acre

POST









7

V10142

6.4

oz/acre

PRE

65

82

261

127

470

48

4

1.0780


Dual Magnum

1.0

pt/acre

PRE










V10142

8.5

oz/acre

POST










MSO

1.6

pt/acre

POST









8

Matrix

1.0

oz/acre

PRE

69

69

255

191

515

82

29

1.0780


Dual Magnum

1.0

pt/acre

PRE










Matrix

1.0

oz/acre

POST










MSO

1.6

pt/acre

POST









9

Dual Magnum

1.0

pt/acre

PRE

56

67

231

180

478

47

9

1.0770


Sencor 4

0.38

pt/acre

PRE










V10142

8.5

oz/acre

POST










MSO

1.6

pt/acre

POST









10

Dual Magnum

1.0

pt/acre

PRE

66

71

270

180

522

45

18

1.0775


Sencor 4

0.38

pt/acre

PRE










Matrix

1.0

oz/acre

POST










MSO

1.6

pt/acre

POST









11

Eptam 7E

4.5

pt/acre

PRE

54

96

247

116

459

76

9

1.0813


Prowl H2O

1.58

pt/acre

PRE










Dual Magnum

1.0

pt/acre

PRE









12

untreated




55

87

206

106

400

28

2

1.0848

LSD (P = 0.05)

NS

24.4

57.2

45.4

79.7

41.3

21.5

NS

CV

34.43

23.61

16.87

21.57

12.3

46.96

120.79

0.77

aMSO = Methylated seed oil. bTiming PRE = Pre-emergence, POST = Post-emergence.