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

 

PUMPKIN WEED CONTROL STUDY

Richard Greenland


Results summary

Table 73. Herbicide treatments

Table 74. Early stand, number and yield of pumpkins, and fruit size

Table 75. Pumpkin injury, pumpkin height, and control of redroot pigweed and lambsquarters

Table 76. Control of hairy nightshade, eastern black nightshade and foxtail


          Weed control is difficult in pumpkins because few herbicides are available for pumpkin production. In this experiment we looked at several herbicides and herbicide combinations for use in pumpkins.


MATERIALS AND METHODS


Soil:

Maddock sandy loam; pH=6.9; 2.3% organic matter; soil-P and soil-K were very high; soil-S was low.

Previous crops:

2002 - field corn; 2001 - cabbage; 2000 - onion.

Seedbed

preparation:

Disked twice on April 11. Multiweeded (field cultivated) on May 22 to smooth the seedbed.

Planting:

Pumpkin seeds planted 1 ft apart in rows 8 ft apart on May 23. On June 20, thinned to an in-row spacing of one plant every 3 ft.

Plots:

Plots were 20 ft long by 8 ft (one row) wide. The study had 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 30 lbs N/acre as 32-0-0 on May 13. Fertigated 50 lbs N/acre as 28-0-0 on June 26.

Irrigation:

Overhead sprinkler irrigation as needed.

Pest control:

Weed control treatments are given in Table 73. Sprayed Asana (8 oz/acre on July 8, 17 and August 22) and Pounce (8 oz/acre on August 6 ) to control cucumber beetle.

Harvest:

Hand harvested on September 26.


RESULTS


          Authority controlled all weeds except hairy nightshade. Outlook gave good control of pigweed and foxtail, but poor control of lambsquarters and hairy nightshade. Raptor controlled pigweed, nightshade, and foxtail, but was weak on lambsquarters. It also injured the pumpkin plants except when applied with Authority. Sandea gave very good pigweed control, but poor lambsquarters, nightshade and foxtail control. Yields were lower with Sandea due to weed competition. Best yields were with the handweeded check and with treatments containing Authority. The most promising herbicides for pumpkin tested in this study were Authority in combination with either Outlook or Raptor. However, none of these three herbicides is currently labeled for pumpkin production.


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Table 73. Herbicide treatments in the Oakes Irrigation Research Site 2003 pumpkin weed control study.

Treatment number

Herbicide(s)

Rate per acre

Application timing1

1

Authority

3 oz

PRE

2

Outlook

1 pt

PRE

3

Raptor

5 oz

PRE

4

Authority + Raptor

2 oz + 4 oz

PRE

5

Outlook + Raptor

1 pt + 4 oz

PRE

6

Outlook + Authority

1 pt + 2 oz

PRE

7

Sandea

½ oz

PRE

8

Outlook + Sandea

1 pt + ½ oz

PRE

9

Sandea + NIS

½ oz

POST

10

Outlook + Sandea + NIS

1 pt + ½ oz

PRE + POST

11

Handweeded check

 

 

12

Unweeded check

 

 

1PRE treatments were applied on May 23. POST treatment was applied on June 19 with pumpkins 5 to 6 inches tall and 15 inches across and in the 3.5 leaf stage, and weeds 2 to 4 inches tall. All Treatments were applied with a CO2 backpack sprayer using AI 110-04 flat fan nozzles, 45 gpa, at 57 psi.


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Table 74. Early stand, number and yield of pumpkins, and fruit size in the Oakes Irrigation Research Site 2003 pumpkin weed control study.

Treatment

number1

Early

stand2

Number of pumpkins

Pumpkin yield

Fruit

size

marketable

total

marketable

total

 

Plants/plot

--- 1000s/acre --

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

lbs/fruit

 

1

12.5

1.4

2.0

11.7 ab3

15.7 bc

16.5 a-d

2

12.8

1.1

1.7

6.9 bcd

9.1 de

12.1 c-f

3

11.5

1.0

1.8

8.5 bc

12.8 cd

14.4 b-e

4

13.3

1.2

1.8

12.0 ab

18.2 bc

20.4 a

5

11.3

1.3

1.9

10.7 ab

15.5 bc

16.7 abc

6

13.8

1.5

2.6

14.7 a

23.8 a

20.5 a

7

13.3

0.8

1.7

3.8 cd

7.4 de

9.0 f

8

10.8

0.6

1.3

3.5 cd

8.2 de

11.6 def

9

10.3

0.5

1.3

2.2 d

6.4 e

8.1 f

10

11.8

1.4

2.0

11.2 ab

15.3 bc

15.6 b-e

11

13.2

1.7

2.2

15.5 a

20.4 ab

18.7 ab

12

11.3

1.3

1.8

6.9 bcd

8.7 de

11.3 ef

 

Probability

0.34

0.06

0.07

0.0002

<.0001

<.0001

C. V. (%)

17

44

27

44

28

22

1See Table 73 for list of treatments.

2Stand before thinning. Maximum value possible was 17. Pumpkins were later thinned to one plant every 3 ft (6 plants/plot).

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 columns without letters.


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Table 75. Pumpkin injury, pumpkin height, and control of redroot pigweed and lambsquarters by herbicides in the Oakes Irrigation Research Site 2003 pumpkin weed control study.

Treatment

number1

Pumpkin injury

Pumpkin height

Pigweed control

Lambsquarters control

June 19

July 16

Aug 1

June 19

June 19

July 16

Aug 1

June 19

July 16

Aug 1

 

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

inches

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

 

1

2.5

0.0

1.3

6.3

9.8

8.8

8.8

9.8

9.5

9.0

2

0.3

0.8

0.8

6.0

10.0

10.0

10.0

4.8

4.0

4.0

3

4.0

0.8

1.3

3.5

10.0

9.5

8.8

8.8

7.8

7.0

4

1.0

0.0

0.5

5.8

10.0

9.8

9.8

9.3

8.8

8.0

5

3.3

0.0

0.5

4.5

10.0

9.5

9.3

8.0

6.5

6.8

6

1.3

0.0

0.0

5.8

10.0

9.5

9.5

9.3

9.0

8.0

7

0.0

1.8

2.8

6.5

10.0

10.0

10.0

6.8

5.5

4.5

8

0.3

1.0

0.8

5.8

10.0

10.0

10.0

5.8

5.3

4.0

9

0.3

1.8

2.5

6.5

8.3

10.0

10.0

6.3

5.8

5.8

10

0.5

0.3

0.5

6.5

10.0

10.0

9.5

6.3

5.3

4.8

11

0.8

0.0

0.3

6.3

7.8

10.0

10.0

5.0

10.0

10.0

12

0.0

1.0

1.0

6.8

8.0

8.3

8.5

5.8

4.8

4.8

 

Probability

<.0001

0.011

0.003

<.0001

<.0001

0.001

0.0012

<.0001

<.0001

<.0001

LSD(0.05)

1.3

1.2

1.3

1.0

0.5

0.8

0.8

1.9

1.9

1.5

C.V. (%)

80

133

91

12

4

6

6

19

19

17

1See Table 73 for list of treatments.

2Ratings from 0 to 10 with 0 = no pumpkin injury, no weed control; 10 = complete death of pumpkin or weed completely controlled.


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Table 76. Control of hairy nightshade, eastern black nightshade and foxtail by herbicides in the Oakes Irrigation Research Site 2003 pumpkin weed control study.

Treatment

number1

Hairy nightshade control

Eastern black nightshade control

Foxtail control

June 19

July 16

Aug 1

June 19

July 16

Aug 1

June 19

July 16

Aug 1

 

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

 

1

9.0

7.3

5.5

10.0

9.8

9.8

9.3

9.0

8.0

2

8.5

7.5

5.8

10.0

10.0

10.0

9.8

10.0

8.8

3

10.0

10.0

9.5

10.0

10.0

9.8

10.0

8.8

8.0

4

10.0

10.0

8.8

10.0

9.8

9.5

10.0

8.8

8.8

5

10.0

9.5

8.5

10.0

9.8

9.5

10.0

9.8

10.0

6

9.8

8.5

7.8

10.0

10.0

9.5

10.0

9.5

9.3

7

4.8

3.3

3.3

7.5

7.5

7.0

9.8

9.3

8.5

8

8.5

5.5

4.5

10.0

9.8

9.8

9.8

9.5

8.5

9

6.0

4.5

3.3

7.8

7.3

7.0

8.0

8.0

6.3

10

8.8

6.5

5.3

10.0

9.8

9.0

10.0

9.8

9.0

11

5.8

10.0

10.0

7.8

10.0

10.0

9.5

10.0

10.0

12

6.3

6.0

4.8

7.5

8.3

8.0

8.8

6.8

6.8

 

Probability

<.0001

<.0001

<.0001

<.0001

0.0001

0.0004

0.011

0.014

0.0003

LSD (0.05)

1.6

2.2

1.9

1.2

1.3

1.5

1.1

1.7

1.5

C.V. (%)

13

20

21

9

10

12

8

13

12

1See Table 73 for list of treatments.

2Ratings from 0 to 10 with 0 = no pumpkin injury, no weed control; 10 = complete death of pumpkin or weed completely controlled.


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