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 60. Herbicide treatments

Table 61. Pumpkin injury and control of redroot pigweed and lambsquarters by herbicides

Table 62. Control of hairy nightshade, eastern black nightshade and foxtail by herbicides

Table 63. Early stand, number and yield of pumpkins, and fruit size


           Weed control is difficult in pumpkins because few herbicides are available for pumpkin production. A new herbicide, Sandea, recently came on the market for use in pumpkins. We tested this herbicide and looked at several other herbicides and herbicide combinations for use in pumpkins.


MATERIALS AND METHODS


Soil:

Maddock sandy loam, Embden sandy loam, and Hecla sandy loam; pH=6.2; 2.6% organic matter; soil-P was very high, soil-K was high; soil-S was low.

Previous crops:

2003 - field corn; 2002 - cabbage; 2001 - pumpkin.

Seedbed

preparation:

Disked on April 13 and on May 26. Multiweeded (field cultivated) on May 26 to smooth the seedbed and on May 27 to incorporate fertilizer.

Planting:

‘New Rocket’ pumpkin seeds were planted 1 ft apart in rows 8 ft apart on May 27. On July 5 thinned to an in-row spacing of one plant every 3 ft.

Plots:

Plots were 17 ft long by 8 ft (one row) wide. The study had 4 reps.

Fertilizer:

On April 15 broadcast 20 lbs N/acre and 24 lbs S/acre as 20-0-0-24. Applied 50 lbs N/acre on May 27 as 28-0-0. Applied 50 lbs N/acre on July 16 as urea.

Irrigation:

Underground drip irrigation as needed.

Pest

control:

Weed control treatments are given in Table 60. No cucumber beetle control needed.

Harvest:

Hand harvested on September 20 to September 22.


RESULTS


           Outlook injured pumpkins early but the injury soon disappeared. The July 22 injury ratings (Table 61) reflect the reduced growth of pumpkins caused by weed competition (see Tables 61 and 62), which was most severe with the Sandea PRE treatment because it didn’t control hairy nightshade. Authority gave good to excellent control of all weeds except hairy nightshade. Outlook gave good control of pigweed but poor control of lambsquarters and hairy nightshade. Raptor controlled pigweed and gave good control of nightshade and fair to good control of lambsquarters. Sandea gave excellent pigweed control, but poor nightshade control. It controlled lambsquarters when applied PRE but not when applied POST. Yields were lower with Sandea and Outlook treatments due to weed competition. Best yields were with the hand weeded check and with treatments containing Authority (Table 63). 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 60. Herbicide treatments in the Oakes Irrigation Research Site 2004 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

Hand weeded check

12

Unweeded check

1PRE treatments were applied on May 27. POST treatments were applied on June 23 with pumpkins 3 to 5 inches tall and 10 to 15 inches across. Weeds were 1 to 3 inches tall. All treatments were applied with a CO2 pressurized backpack sprayer using AI 110-04 flat fan

nozzles, 45 gpa, at 57 psi.


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Table 61. Pumpkin injury and control of redroot pigweed and lambsquarters by herbicides in the Oakes Irrigation Research Site 2004 pumpkin weed control study.

Treatment

number1

Pumpkin injury

Redroot pigweed control

Lambsquarters control

June 18

July 22

June 18

July 22

June 18

July 22

 

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

 

1

3.3

0.5

9.0

7.5

10.0

10.0

2

4.3

2.8

9.8

9.3

7.0

4.0

3

0.5

0.8

10.0

10.0

7.5

7.0

4

2.0

0.0

9.8

8.8

10.0

9.5

5

4.0

0.5

10.0

10.0

9.3

7.3

6

3.0

0.3

9.5

9.0

10.0

9.8

7

2.3

6.5

10.0

10.0

10.0

10.0

8

3.5

3.5

10.0

10.0

9.8

9.8

9

0.0

3.5

4.8

9.5

6.5

3.5

10

3.8

2.8

10.0

10.0

6.8

2.8

11

0.0

0.0

9.0

9.8

8.8

10.0

12

0.0

6.5

6.0

7.5

5.5

2.5

 

Probability

<0.0001

<0.0001

<0.0001

0.0001

<0.0001

<0.0001

LSD(0.05)

1.0

1.3

1.0

1.2

1.3

1.5

C.V. (%)

32

39

7

9

11

14

1See Table 60 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 62. Control of hairy nightshade, eastern black nightshade and foxtail by herbicides in the Oakes Irrigation Research Site 2004 pumpkin weed control study.

Treatment

number1

Hairy nightshade control

Eastern black nightshade control

Foxtail control

June 18

July 22

June 18

July 22

June 18

July 22

 

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

 

1

7.3

5.3

10.0

10.0

8.5

8.3

2

8.5

6.0

9.8

10.0

10.0

10.0

3

8.0

8.0

9.3

10.0

7.3

5.8

4

6.8

5.8

10.0

10.0

8.3

7.3

5

8.8

7.8

10.0

10.0

10.0

9.8

6

9.3

6.8

10.0

10.0

10.0

10.0

7

3.0

0.3

9.3

9.5

9.0

8.0

8

6.8

2.0

9.5

10.0

9.8

10.0

9

6.0

5.0

9.3

10.0

8.5

8.8

10

7.8

6.3

9.5

10.0

10.0

10.0

11

8.5

9.8

10.0

10.0

9.5

10.0

12

4.3

5.3

9.8

9.8

7.8

7.5

 

Probability

<0.0001

<0.0001

0.02

0.55

<0.0001

<0.0001

LSD (0.05)

1.8

1.5

0.6

1.1

1.4

C.V. (%)

18

19

4

3

9

11

1See Table 60 for list of treatments.

2Ratings from 0 to 10 with 0 = no weed control; 10 = weed completely controlled.


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Table 63. Early stand, number and yield of pumpkins, and fruit size in the Oakes Irrigation Research Site 2004 pumpkin weed control study.

Treatment

number1

Early

stand2

Number of pumpkins

Pumpkin yield

Fruit

size

Overall

score

marketable

total

marketable

total

 

1000s/acre

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

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

lbs/fruit

1 to 10

 

1

4.0 c3

2.0 b

3.6 ab

14.9 bc

21.2 c

15.3 ab

7.5 ab

2

4.6 bc

0.8 d

2.4 cde

3.7 de

6.9 ef

9.6 c

6.8 c

3

4.1 c

2.1 b

3.2 bc

15.1 b

20.3 c

13.8 b

7.6 a

4

4.7 abc

2.1 b

3.2 abc

16.4 b

21.5 bc

15.4 ab

7.5 ab

5

5.4 a

1.9 b

2.6 cd

15.9 b

17.5 cd

17.6 a

7.5 ab

6

4.4 bc

2.3 b

3.5 ab

19.2 b

27.4 b

16.2 ab

7.5 ab

7

4.6 bc

0.9 d

1.5 f

2.9 de

3.9 fg

6.4 d

6.8 c

8

5.0 ab

1.7 bc

2.5 cde

8.4 cd

12.7 de

9.6 c

7.1 bc

9

4.7 abc

0.9 cd

1.6 ef

4.2 de

5.8 fg

8.9 cd

7.1 bc

10

4.4 bc

0.9 d

2.0 def

3.4 de

7.3 ef

7.2 cd

6.9 c

11

4.6 bc

3.3 a

4.1 a

28.4 a

33.6 a

17.2 a

7.6 a

12

4.6 bc

0.3 d

0.3 g

0.5 e

0.5 g

5.0 cd

6.9 abc

 

Probability

0.04

<0.0001

<0.0001

<0.0001

<0.0001

<0.0001

0.001

C. V. (%)

11

35

25

42

28

18

5

1See Table 60 for list of treatments.

2Plant stand before thinning. Pumpkins were later thinned to one plant every 3 ft (about 1815 plants/acre).

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


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