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 63. Carrot weed control treatment application data

Table 64. Carrot root characteristics as effected by herbicides

Table 65. Crop injury by herbicides

Table 66. Hairy nightshade, eastern black nightshade, and redroot pigweed control

Table 67. Number of roots and yield of carrots



          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 several new herbicides and herbicide combinations for use in carrots.

 

MATERIALS AND METHODS


Soil:

Maddock sandy loam; pH=6.9; 2.1% organic matter; soil-P and soil-K were very high; soil-S was low.

Previous crop:

2002 - potato; 2001 - cabbage, carrot, edible bean, field corn, onion, potato, soybean, sugar beet, sweetcorn and wheat; 2000 - field corn.

Seedbed

Preparation:

Chisel plowed once on April 24. Disked on April 24. Multiweeded (field cultivated) three times; once May 8 to smooth seedbed and twice May 16 to incorporate herbicide.

Planting:

Direct seeded Bolero carrots on May 16 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 9, broadcast 11 lbs N/acre and 52 lbs P205 as 11-52-0, 30 lbs K2O as 0-0-60 and 18 lbs N/acre and 20 lbs S/acre as 21-0-0-24. Side dressed 40 lbs N/acre as 32-0-0 on May 13. Fertigated 50 lbs N/acre as 28-0-0 on June 26. Applied 30 lbs N/acre as urea on July 16.

Irrigation:

Overhead sprinkler irrigation as needed.

Pest

control:

Treflan (1.5 pt/acre on May 16) and Poast + Dash (1.5 pt + 1 pt/acre on June 17) were applied to all plots. Check plots were hand weeded. See Table 65 for other weed control treatments. Sprayed Asana (8 oz/acre on July 17, July 30, August 8 and August 22) to control leafhopper.

Harvest:

Carrots were harvested September 12 to September 16. The harvest area was a 3 ft section of the center two rows of each plot.

 

RESULTS


          Weed pressure was low this year and weed control was good to excellent for all treatments except for Balance Pro which did not control hairy nightshade. Callisto severely injured carrots when applied PRE, but only slightly injured carrots when applied at POST2 when carrots were three inches tall. Balance Pro injured carrots severely, moderately, or very slightly when applied PRE, POST1, or POST2, respectively. Authority and Valor also slightly injured carrots. Most treatments gave yields equal with the check. Callisto applied PRE and all Balance Pro treatments gave lower yields. Valor reduced carrot stand when applied PRE, but carrots were bigger so yield was not reduced.


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Table 63. Carrot weed control treatment application data at the Oakes Irrigation Research Site in 2003.

Application

timing

Date

Time

Barley

height

Carrot

height

Carrot

growth stage

Weed

height

Weed

growth stage

PRE

May 20

11:00 am

0

0

0

0

0

POST1

June 16

9:35 am

7"

3"

2 lf

1 to 4”

3 to 8 lf

POST2

June 23

3:00 pm

8" (dying)

4.5"

3.5 lf

1 to 6"

4 to 10 lf

Treatments were applied with a CO2 backpack sprayer using AI 110-04 flat fan nozzles, 45 gpa, at 57 psi. Weed ratings were taken on June 27, August 1 and September 5.

Treflan (1.5 pt/A on May 16) and Poast + Dash (1.5 pt + 1 pt/A on June 17) applied to entire study.


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Table 64. Carrot root characteristics for the Oakes Irrigation Research Site 2003 carrot weed control study.

Treatment

 number1

Average

root length

Average

root size

Multiple

root

US #1

yield

Uniformity

Overall

score

 

inches

oz/root

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

1 to 5

1 to 10

 

1

6.0

2.5 f2

22

71

2.4

6.4

2

6.5

3.6 cde

22

74

2.5

6.5

3

6.6

5.7 a

19

79

2.3

6.3

4

7.4

4.3 bc

21

76

2.5

6.5

5

6.5

4.8 ab

31

66

2.4

6.4

6

6.5

3.0 def

24

71

2.5

6.5

7

6.6

3.4 c-f

18

81

2.5

6.6

8

6.6

3.9 bcd

31

65

2.4

6.4

9

6.1

2.7 ef

21

73

2.4

6.4

10

6.3

3.3 c-f

25

70

2.5

6.5

11

6.0

3.2 c-f

30

68

2.5

6.5

12

6.5

2.5 ef

23

71

2.4

6.4

13

6.3

3.3 c-f

13

84

2.4

6.4

15

6.8

3.1 def

25

70

2.5

6.5

16

6.1

3.0 def

24

72

2.3

6.3

17

6.3

3.3 c-f

29

65

2.3

6.3

18

6.3

3.0 def

24

73

2.5

6.5

 

Probability

0.08

<.0001

0.6

0.43

0.68

0.45

C.V. (%)

8

23

41

14

9

3

1See Table 65 for weed control treatments.

2Values in this column followed by the same letter are not significantly different at the 0.05 level. No significant differences between values in columns without letters.


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Table 65. Crop injury by herbicides in the Oakes Irrigation Research Site 2003 carrot weed control study.

Treatment

Number

Herbicide(s)

Application

Rate

Application

timing1

Crop Injury

Jun 27

Aug 1

Sept 5

 

------------------ 0 to 102 ----------------

 

1

Lorox

1 lb

PRE

0.5 ab3

0.3 ab

1.0 abc

2

Balance Pro

1 oz

PRE

5.5 h

4.8 d

4.8 e

3

Balance Pro

1.5 oz

PRE

7.5 i

7.0 e

4.5 e

4

Valor

0.5 oz

PRE

2.5 def

1.8 bcd

0.5 ab

5

Valor

1 oz

PRE

3.0 ef

2.5 cd

2.0 bcd

6

Lorox + Lorox

1 lb + 1.5 lbs

PRE + POST2

0.5 ab

0.0 a

1.3 abc

7

Lorox + Valor

0.5 lb + 2 oz

PRE + POST2

2.3 de

1.8 bcd

1.3 abc

8

Valor + Lorox

0.5 oz + 1.5 lbs

PRE + POST2

1.8 cd

1.0 abc

0.5 ab

9

Lorox + Balance Pro

1 lb + 1 oz

PRE + POST2

1.0 abc

1.3 a-d

1.5 abc

10

Lorox + Valor

1 lb + 1 oz

PRE + POST2

2.3 de

1.3 a-d

1.3 abc

11

Lorox + Valor

1 lb + 2 oz

PRE + POST2

1.8 cd

1.5 a-d

0.0 a

12

Lorox + Authority

1 lb + 1 oz

PRE + POST2

3.0 ef

0.3 ab

1.3 abc

13

Lorox + Authority

1 lb + 2 oz

PRE + POST2

3.5 fg

1.8 bcd

0.5 ab

14

Callisto + Lorox

6 oz + 1.5 lb

PRE + POST2

10.0 j

9.0 f

9.5 f

15

Lorox + Callisto

1 lb + 3 oz

PRE + POST2

1.5 bcd

2.3 cd

0.8 abc

16

Balance Pro

1 oz

POST1

3.5 fg

2.3 cd

3.3 de

17

Balance Pro

1.5 oz

POST1

4.3 g

2.5 cd

2.3 cd

18

Hand weeded check

 

 

0.0 a

0.0 a

0.5 ab

 

Probability

<.0001

<.0001

<.0001

C.V. (%)

27

52

59

1See Table 63 for explanation of application timings.

2Ratings are from 0 to 10: 0 = no weed control or crop injury, 10 = complete weed control or all carrots dead.

3Values in the same column followed by the same letter are not significantly different at the 0.05 level.


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Table 66. Hairy nightshade, eastern black nightshade, and redroot pigweed control by herbicides in the Oakes Irrigation Research Site 2003 carrot weed control study.

Treatment

number1

Hairy Nightshade

Eastern Black Nightshade

Redroot Pigweed

Jun 27

Aug 1

Sept 5

Jun 27

Aug 1

Sept 5

Jun 27

Aug 1

Sept 5

 

------------------------------------------------------------ 0 to 102 -----------------------------------------------------------

 

1

9.3 abc3

6.5 b

6.8 d-g

9.8 ab

7.8 c

7.5 cd

10.0

9.0 abc

9.3 abc

2

8.3 cd

4.5 c

4.0 h

10.0 a

9.3 ab

9.3 ab

10.0

8.3 c

7.8 de

3

9.5 ab

6.0 bc

5.8 fgh

10.0 a

9.8 a

9.3 ab

10.0

8.8 bc

7.8 de

4

10.0 a

9.0 a

9.5 ab

10.0 a

10.0 a

10.0 a

10.0

9.0 abc

8.5 cd

5

10.0 a

9.8 a

9.8 ab

10.0 a

10.0 a

9.8 a

10.0

9.0 abc

8.8 bcd

6

9.3 abc

9.0 a

8.5 a-d

10.0 a

10.0 a

10.0 a

10.0

9.8 ab

9.5 abc

7

9.8 a

10.0 a

10.0 a

10.0 a

10.0 a

10.0 a

10.0

10.0 a

10.0 a

8

10.0 a

9.8 a

10.0 a

10.0 a

10.0 a

10.0 a

10.0

10.0 a

9.8 ab

9

8.3 cd

6.5 b

6.0 fg

10.0 a

9.8 a

9.5 a

10.0

10.0 a

9.5 abc

10

9.8 a

9.8 a

10.0 a

10.0 a

10.0 a

10.0 a

10.0

9.8 ab

9.5 abc

11

9.8 a

10.0 a

9.8 ab

9.8 ab

10.0 a

10.0 a

10.0

10.0 a

9.9 ab

12

9.3 abc

6.3 b

6.5 efg

10.0 a

9.5 a

9.8 a

10.0

10.0 a

9.8 ab

13

10.0 a

9.0 a

8.0 b-e

10.0 a

10.0 a

10.0 a

10.0

10.0 a

10.0 a

14

10.0 a

10.0 a

9.0 abc

10.0 a

10.0 a

9.5 a

10.0

8.8 bc

7.0 e

15

8.3 cd

10.0 a

10.0 a

10.0 a

10.0 a

10.0 a

10.0

9.0 abc

8.5 cd

16

8.0 d

5.0 bc

5.0 gh

9.8 ab

8.0 bc

7.8 bd

10.0

9.3 abc

8.8 bcd

17

7.8 de

5.5 bc

5.0 gh

10.0 a

9.3 ab

8.8 abc

10.0

9.0 abc

8.8 bcd

18

6.5 f

10.0 a

10.0 a

8.8 c

10.0 a

10.0 a

10.0

10.0 a

10.0 a

 

Probability

<.0001

<.0001

<.0001

<.0001

<.0001

0.0012

0.005

<.0001

C.V. (%)

9

14

17

4

9

12

0

8

9

1See Table 65 for weed control treatments.

2Ratings are from 0 to 10: 0 = no weed control or crop injury, 10 = complete weed control or all carrots dead.

3Values in the same column followed by the same letter are not significantly different at the 0.05 level. No significant differences between values in column without letters.


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Table 67. Number of roots and yield of carrots in the Oakes Irrigation Research Site 2003 carrot weed control study.

Treatment

number1

Number of carrot roots (by carrot dia.)

Carrot yield (by carrot diameter)

>1.5"

1 to 1.5"

0.5 to 1"

US #1

total

>1.5"

1 to 1.5"

0.5 to 1"

US #1

total

 

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

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

 

1

56 b-e2

113 ab

110 a

278 ab

375 a

9.5 b-e

8.7 a-f

3.6 a

21.8 ab

31.4 ab

2

30 ef

  58 ef

  15 jk

103 fg

143 de

5.6 ef

5.6 fgh

0.5 ghi

11.7 d

16.0 de

3

35 def

  22 fg

  11 jk

  68 g

  91 e

7.8 cde

1.9 ij

0.4 hi

10.1 d

13.6 e

4

71 a-d

  68 de

  33 f-j

172 de

215 cd

14.6 abc

7.0 c-h

1.4 d-h

23.0 ab

30.4 abc

5

97 a

  59 ef

  16 ijk

172 de

236 c

18.7 a

5.9 fgh

0.5 ghi

25.0 ab

37.4 a

6

76 abc

120 ab

  79 a-d

275 ab

385 a

13.6 a-d

9.0 a-e

2.5 bc

25.0 ab

35.5 ab

7

86 ab

123 ab

  59 d-h

269 ab

332 ab

14.9 ab

10.9 a

2.2 bcd

27.9 a

34.6 ab

8

80 abc

  70 cde

  47 d-i

197 cde

280 bc

15.6 ab

6.6 d-h

1.5 c-g

23.7 ab

36.0 ab

9

69 a-e

108 abc

  64 b-f

241 abc

361 a

10.7 b-e

7.7 b-g

2.0 b-e

20.4 bc

28.2 bc

10

74 a-d

117 ab

  62 c-g

253 abc

338 ab

13.3 a-d

9.5 a-d

2.3 bcd

25.1 ab

35.9 ab

11

75 a-d

131 a

  41 e-j

247 abc

332 ab

12.6 a-e

10.7 ab

1.4 c-h

24.6 ab

36.6 ab

12

62 a-e

138 a

  96 ab

295 a

391 a

10.6 b-e

10.0 abc

2.9 ab

23.5 ab

33.1 ab

13

87 ab

126 a

  69 b-e

282 a

365 a

15.8 ab

10.4 ab

2.4 bcd

28.5 a

34.4 ab

14

  0 f

    0 g

    0 k

    0 h

    0 f

0.0 f

0.0 j

0.0 i

0.0 e

0.0 f

15

76 abc

103 a-d

  64 b-f

243 abc

357 ab

13.8 a-d

8.0 a-g

2.1 bcd

23.9 ab

34.0 ab

16

44 cde

  69 de

  31 g-k

144 ef

220 cd

7.3 de

5.2 gh

1.0 e-i

13.5 cd

19.3 de

17

54 b-e

  58 ef

  28 h-k

140 ef

230 c

9.7 b-e

4.4 hi

0.7 f-i

14.8 cd

22.4 cd

18

82 abc

128 a

  93 abc

304 a

385 a

14.9 ab

10.8 a

2.8 ab

28.5 a

38.6 a

 

Probability

0.002

<.0001

<.0001

<.0001

<.0001

0.0006

<.0001

<.0001

<.0001

<.0001

C.V. (%)

43

30

43

22

20

42

30

44

24

21

1See Table 65 for weed control treatments.

2Values in the same column followed by the same letter are not significantly different at the 0.05 level.


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