Oakes Irrigation Research Site
Carrington Research Extension Center * North Dakota State University
P.O. Box 531, Oakes, ND 58474-0531, Voice: (701) 742-2189, FAX: (701) 742-2700, email: rgreenla@ndsuext.nodak.edu

 

CARROT WEED CONTROL STUDY

Richard Greenland


Results summary

Table 42. Weed control and crop injury

Table 43. Number of roots and yield of carrots

Table 44. Carrot root characteristics and quality

Tables of pesticides used at the Oakes Irrigation Research Site -- Trade names and common names


           Only a few herbicides are available for weed control in carrots. Treflan, Lorox, Poast and Fusilade are the most commonly used. In this study we evaluated five additional herbicides, Authority, Outlook, Dual II Magnum, Dacthal, and Valor, for their usefulness in carrot production.


MATERIALS AND METHODS


Soil:

Embden loam and Maddock sandy loam; pH=7.3; 2.1% organic matter; soil-P and soil-K were very high; soil-S was medium.

Previous crop:

2001 - potato; 2000 - pepper, onion, edible bean, field corn, sweetcorn, soybean, carrot, and cabbage; 1999 - field corn and ornamental corn.

Seedbed

Preparation:

Coulter chiseled 15 inches deep twice – once on Apr 17 and again on Apr 18. Multiweeded (field cultivated) three times; once May 16 to smooth seedbed and twice May 20 to incorporate herbicide.

Planting:

Direct seeded Bolero carrots on May 21 with a Monosem precision vacuum planter set to plant a row of barley cover crop between the carrot rows. Carrot planting pattern was 3 lines per row (2 inches between lines in the row) with rows on 18-inch centers. Planting rate was about 800,000 seeds/acre for carrot and 0.45 bu/acre for barley.

Plots:

Plots were 17 ft long by 6 ft wide with a 2-ft border between plots. There were 4 reps.

Fertilizer:

On April 18, broadcast 18 lbs N/acre and 20 lbs S/acre as 21-0-0-24. Side dressed 50 lbs N/acre as urea on July 3.

Irrigation:

Overhead sprinkler irrigation as needed.

Pest

control:

Treflan (1.5 pt/acre on May 20) and Poast + Dash (1.5 pt + 1 pt/acre on June 17) were applied to all plots. Check plots were hand weeded. See Table 42 to 44 for other weed control treatments. Sprayed Asana (8 oz/acre on July 15, July 30 and Aug 13) and Sevin (1 qt/acre on Aug 27) to control leafhopper.

Harvest:

Carrots were harvested on September 11 to17. The harvest area was 3 ft of the center two rows of each plot.


RESULTS


           Goal applied at either PRE or POST1 (carrots 1.5 inches tall) injured carrot plants and reduced carrot stand and yields. Valor injured carrot plants and reduced carrot stand and yields if applied PRE or POST1, but not when applied POST2 (carrots 3 inches tall). The best weed control and highest yields were with Lorox applied PRE and POST2, or with Dacthal applied EPOST followed by Lorox at POST2. The Lorox PRE followed by Valor POST2 treatment also produced good weed control and high yields. Authority applied POST2 did not control hairy nightshade and slightly injured carrots, resulting in lower carrot yields.


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Table 42. Weed control and crop injury for the Oakes Irrigation Research Site 2002 carrot weed control study.

Herbicide(s)

Rate

Application timing2

June 24 ratings1

July 3 ratings1

crop injury

Colq3

Hns3

Ebns3

crop injury

Colq3

Hns3

 

 

 

------------------------------------------- 0 to 10 --------------------------------------------

 

Lorox

1 lb

PRE

0.8

9.3

7.8

9.8

0.5

9.3

7.0

Dacthal + Lorox

8 lbs + 1.5 lb

EPOST + POST2

0.3

10.0

 7.3

10.0

0.3

10.0

 9.8

Lorox + Dacthal

1 lb + 8 lbs

PRE + EPOST

1.0

10.0

 9.8

10.0

0.8

10.0

10.0

Goal 2XL

1 pt

PRE

4.8

10.0

10.0

10.0

3.5

10.0

10.0

Goal 2XL

1 pt

POST1

4.3

10.0

10.0

10.0

3.3

10.0

10.0

Goal 2XL

2 pt

PRE

7.8

10.0

10.0

10.0

8.0

10.0

10.0

Goal 2XL

2 pt

POST1

5.3

10.0

10.0

10.0

4.8

10.0

10.0

Valor

0.5 oz

PRE

2.0

 9.8

 9.5

10.0

1.3

 9.5

 9.5

Valor

1 oz

PRE

2.8

 9.8

10.0

10.0

3.0

10.0

10.0

Lorox + Valor

1 lb + 1 oz

PRE + POST1

3.8

10.0

10.0

10.0

3.5

10.0

10.0

Lorox + Valor

1 lb + 2 oz

PRE + POST1

5.0

10.0

10.0

10.0

5.3

10.0

10.0

Lorox + Valor

1 lb + 1 oz

PRE + POST2

1.8

 9.5

 8.5

10.0

1.0

 9.3

 8.8

Lorox + Valor

1 lb + 2 oz

PRE + POST2

0.8

 9.3

 8.0

10.0

0.8

 9.3

 8.8

Lorox + Authority

1 lb + 1 oz

PRE + POST2

0.5

 9.8

 7.5

10.0

2.0

10.0

 8.0

Lorox + Authority

1 lb + 2 oz

PRE + POST2

0.8

10.0

 8.5

10.0

2.5

10.0

 9.3

Lorox + Lorox

1 lb + 1.5 lbs

PRE + POST2

1.0

 9.8

 8.8

10.0

1.3

10.0

10.0

Lorox

0.5 lb

PRE

0.0

 9.8

 7.5

10.0

0.0

 9.8

 6.8

Valor + Valor + Lorox

0.5 + 2.0 oz +1.5 lbs

PRE + POST1 + POST2

6.0

10.0

10.0

10.0

6.0

10.0

10.0

Authority

1 oz

POST2

0.0

 9.0

 4.0

 9.0

2.0

 9.5

 4.3

Authority

2 oz

POST2

0.0

 8.8

 4.5

 9.8

2.8

 9.8

 5.8

Hand weeded check

0.0

10.0

10.0

10.0

0.0

10.0

10.0

 

LSD (0.05)

1.3

0.6

1.2

0.3

1.7

0.5

1.6

Probability

<.0001

0.001

<.0001

<.0001

<.0001

0.002

<.0001

C.V. (%)

39

5

10

2

47

4

12

1Ratings are from 0 to 10: 0 = no weed control or crop injury, 10 = complete weed control or all carrots dead.

2PRE was on May 23. EPOST was on June 4 (barley 3 to 5" tall, carrot ½ to 1” tall, weeds ½” tall). POST1 was on June 14 (carrots 1.5"

  tall, weeds 1" tall). POST2 was on June 25 (carrots 3 to 4" tall, weeds (mostly hairy nightshade) 2 to 3" tall (previously treated) or 4

  to 7" tall (previously untreated). Treflan (1.5 pt/A on May 20) and Poast + Dash (1.5 pt + 1 pt/A on June 17) applied to all treatments.

3Colq is common lambsquarters; Hns is Hairy nightshade; Ebns is Eastern black nightshade.


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Table 43. Number of roots and yield of carrots in the Oakes Irrigation Research Site 2002 carrot weed control study.

Herbicide(s)

Rate

Application timing1

Number of carrot roots (by carrot dia.)

Carrot yield (by carrot diameter)

>1.5"

1 to 1.5"

US #1

total

>1.5"

1 to 1.5"

US #1

total

 

 

 

-------------- 1000s/acre --------------

----------------- tons/acre ---------------

 

Lorox

1 lb

PRE

24

  80

129

166

4.3

5.6

10.5

13.3

Dacthal + Lorox

8 lbs + 1.5 lb

EPOST + POST2

80

  59

145

198

14.9

5.5

20.6

29.7

Lorox + Dacthal

1 lb + 8 lbs

PRE + EPOST

57

  34

102

160

10.3

3.3

14.0

22.0

Goal 2XL

1 pt

PRE

51

  33

  87

126

 9.8

2.9

12.9

19.6

Goal 2XL

1 pt

POST1

65

  58

132

161

11.6

5.2

17.0

21.2

Goal 2XL

2 pt

PRE

  8

    7

  16

  33

 2.4

0.6

 3.0

 8.3

Goal 2XL

2 pt

POST1

47

  30

  83

121

 8.9

3.1

12.1

18.4

Valor

0.5 oz

PRE

64

  56

126

162

13.0

4.8

18.0

23.4

Valor

1 oz

PRE

30

  23

  56

110

 6.1

1.9

 8.1

16.3

Lorox + Valor

1 lb + 1 oz

PRE + POST1

67

  30

110

142

13.1

2.8

16.4

22.2

Lorox + Valor

1 lb + 2 oz

PRE + POST1

44

  18

  68

  96

 8.5

1.8

10.5

16.3

Lorox + Valor

1 lb + 1 oz

PRE + POST2

61

  53

123

160

10.7

5.0

16.1

20.3

Lorox + Valor

1 lb + 2 oz

PRE + POST2

70

  96

180

219

12.2

7.8

20.4

24.8

Lorox + Authority

1 lb + 1 oz

PRE + POST2

51

  85

149

189

 8.8

7.3

16.5

20.6

Lorox + Authority

1 lb + 2 oz

PRE + POST2

56

  56

115

155

10.0

4.3

14.4

18.6

Lorox + Lorox

1 lb + 1.5 lbs

PRE + POST2

59

  68

136

175

11.4

6.5

19.0

25.3

Lorox

0.5 lb

PRE

53

  79

161

198

 9.7

6.9

17.3

19.9

Valor + Valor + Lorox

0.5 + 2.0 oz + 1.5 lbs

PRE + POST1 +POST2

33

  12

  46

  73

 7.6

0.9

 8.6

15.5

Authority

1 oz

POST2

  7

  96

137

179

 0.9

4.9

 6.5

 7.5

Authority

2 oz

POST2

15

131

179

209

 2.2

8.0

11.0

12.2

Hand weeded check

90

  85

185

244

16.7

8.7

25.8

32.7

 

LSD (0.05)

30

47

65

76

5.6

3.9

7.5

9.0

Probability

<.0001

<.0001

<.0001

<.0001

<.0001

0.0007

<.0001

<.0001

C.V. (%)

43

59

39

34

43

59

38

33


1PRE was on May 23. EPOST was on June 4 (barley 3 to 5" tall, carrot ½ to 1” tall, weeds ½” tall). POST1 was on June 14 (carrots 1.5"

  tall, weeds 1" tall). POST2 was on June 25 (carrots 3 to 4" tall, weeds (mostly hairy nightshade) 2 to 3" tall (previously treated) or 4

  to 7" tall (previously untreated). Treflan (1.5 pt/A on May 20) and Poast + Dash (1.5 pt + 1 pt/A on June 17) applied to all treatments.


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Table 44. Carrot root characteristics and quality for the Oakes Irrigation Research Site 2002 carrot weed control study.

Herbicide(s)

Rate

Application timing1

Average root length

Average root size

Multiple root yield

US #1 yield

Overall score

 

 

 

inches

oz/root

tons/acre

%

1 to 10

 

Lorox

1 lb

PRE

5.7 de

2.8 def

1.7 d-g

83 ab

6.6 a

Dacthal + Lorox

8 lbs + 1.5 lb

EPOST + POST2

6.9 a-d

4.8 abc

5.8 a

69 b-e

5.0 abc

Lorox + Dacthal

1 lb + 8 lbs

PRE + EPOST

6.3 bcd

4.4 bc

5.5 ab

63 def

4.0 bcd

Goal 2XL

1 pt

PRE

6.9 a-d

4.8 ab

4.6 a-e

67 b-e

6.4 a

Goal 2XL

1 pt

POST1

6.7 a-d

4.4 bc

2.2 b-g

80 abc

6.3 ab

Goal 2XL

2 pt

PRE

7.2 abc

6.3 a

4.2 a-e

40 g

1.5 e

Goal 2XL

2 pt

POST1

6.8 a-d

4.6 bc

4.1 a-e

68 b-e

6.5 a

Valor

0.5 oz

PRE

6.7 a-d

4.5 bc

3.1 a-g

78 a-d

6.6 a

Valor

1 oz

PRE

6.7 a-d

4.9 ab

5.3 abc

50 fg

2.5 de

Lorox + Valor

1 lb + 1 oz

PRE + POST1

7.6 a

5.1 ab

3.5 a-g

74 a-d

5.3 abc

Lorox + Valor

1 lb + 2 oz

PRE + POST1

7.1 abc

4.9 ab

4.4 a-e

63 c-f

5.0 abc

Lorox + Valor

1 lb + 1 oz

PRE + POST2

6.2 cd

4.4 bcd

1.9 c-g

78 a-d

4.8 a-d

Lorox + Valor

1 lb + 2 oz

PRE + POST2

6.4 a-d

4.0 bcd

3.0 a-g

82 ab

7.0 a

Lorox + Authority

1 lb + 1 oz

PRE + POST2

6.1 cd

3.6 b-e

1.2 efg

81 ab

6.3 ab

Lorox + Authority

1 lb + 2 oz

PRE + POST2

6.5 a-d

4.5 bc

2.5 a-g

78 a-d

5.9 ab

Lorox + Lorox

1 lb + 1.5 lbs

PRE + POST2

7.0 abc

4.6 bc

3.6 a-f

74 a-d

5.6 ab

Lorox

0.5 lb

PRE

5.7 de

3.2 cde

1.2 efg

86 a

6.0 ab

Valor + Valor + Lorox

0.5 + 2.0 oz + 1.5 lbs

PRE + POST1 + POST2

7.5 ab

6.3 a

5.7 a

53 efg

3.1 cde

Authority

1 oz

POST2

4.2 f

1.5 f

0.1 g

87 a

4.9 abc

Authority

2 oz

POST2

4.8 ef

2.0 ef

0.6 fg

90 a

7.0 a

Hand weeded check

6.6 a-d

4.6 bc

4.8 a-d

77 a-d

6.1 ab

 

LSD (0.05)

1.2

1.6

3.5

17

2.3

Probability

<.0001

<.0001

0.02

<.0001

0.0001

C.V. (%)

13

26

74

16

30


1PRE was on May 23. EPOST was on June 4 (barley 3 to 5" tall, carrot ½ to 1” tall, weeds ½” tall). POST1 was on June 14 (carrots 1.5"

  tall, weeds 1" tall). POST2 was on June 25 (carrots 3 to 4" tall, weeds (mostly hairy nightshade) 2 to 3" tall (previously treated) or 4

  to 7" tall (previously untreated). Treflan (1.5 pt/A on May 20) and Poast + Dash (1.5 pt + 1 pt/A on June 17) applied to all treatments.


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