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

POTATO WEED CONTROL, 1996

Richard G Greenland

In this study we looked at adjuvants for use with Matrix and the timing of Matrix applications to potatoes.

Result summary

Table 65. Herbicide treatments.

Table 66. Weed control ratings and yield.

MATERIALS AND METHODS

Soil: Egeland loam and Maddock sandy loam; pH=7.4; 2.3% organic matter; soil-P was very high; soil-K was high; soil-S was very low.
Previous crop: 1995 - carrot; 1994 - sweet corn; 1993 - cabbage.
Seedbed preparation: Disked on May 3. Multiweeded (field cultivated) on May 6.
Planting: 'Russet Burbank' placed 1 ft apart in rows 3 ft apart on May 7 and May 13.
Plots: Plots were 20 ft long by 12 ft (four rows) wide.
Fertilizer: On April 17, broadcast 14 lbs N/acre and 70 lbs P2O5/acre as 10-50-0, 16 lbs N/acre and 19 lbs S/acre as 21-0-0-24, and 94 lbs K20/acre as 0-0-60. Fertilized 70 lbs N/acre on June 5 and 50 lbs N/acre on August 2 as 28-0-0.
Irrigation: Overhead sprinkler irrigation as needed.
Pest control: See table 65 for weed control treatments. Sprayed Poast (2 pt/acre) + COC on June 4. Dragged off on May 21. Hilled on June 10 and June 17. Applied Asana (8 oz/acre; sprayed on June 26 and July 8, chemigated on July 12 and July 31) and Sevin (2 qt/acre on July 16 and July 24) for Colorado potato beetle control. Sprayed Manzate (2 lbs/acre on July 16 and Aug 6) and Bravo (1.5 pt/acre on July 24 and Aug. 21) for early and late blight control.
Harvest: Harvested on October 4. Yields, etc. were taken from a eight-foot section of the middle two rows from each plot.

RESULTS

None of the herbicide treatments injured the potatoes. When applied preemergence, the low rate of Matrix alone or with Lexone (treatments 1 and 6) controlled hairy nightshade less than the other treatments. All treatments controlled weeds better than the check treatment. Yields were numerically, but not statistically, higher with treatments vs. the check. Yields for treatments 1 and 6 were numerically, but not statistically, lower than the other treatments.

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Table 65. Herbicide treatments in the Oakes Irrigation Research Station 1996 potato weed control study.
Treatment number Herbicide(s) Rate (oz ai/acre) Application timing1
1 Matrix 0.25 PRE
2 Matrix 0.375 PRE
3 Matrix 0.25 PRE
Matrix + Activator 90 0.25 + 0.25% v/v POST
4 Matrix + Dual 0.25 + 32 PRE
5 Matrix + Prowl 0.25 + 12 PRE
6 Matrix + Lexone 0.25 + 3 PRE
7 Matrix + Activator 90 0.25 + 0.25% v/v POST
8 Matrix + Herbimax 0.25 + 1.0% v/v POST
9 Matrix + Scoil 0.25 + 1.0% v/v POST
10 Matrix + NORTH DAKOTA-4 0.25 + 1.0% v/v POST
11 Matrix + NORTH DAKOTA-72 0.25 + 1.0% v/v POST
12 Matrix + Lexone + Activator 90 0.25 + 3 + 0.25% POST
13 Matrix + Activator 90 0.375 + 0.25% v/v POST
14 Untreated

1PRE is preemergence on June 17, just after the last hilling. POST is post emergence on June 28 when the potatoes were 14 inches tall and the weeds were about ½ inch tall.

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Table 66. Weed control ratings and yield for the Oakes Irrigation Research Station 1996 potato weed control study.
Treatment number1 Weed ratings Number of tubers Tuber yield
July 12 July 26 Sept. 11
hairy nightshade yellow foxtail redroot pigweed hairy nightshade redroot pigweed hairy nightshade yellow foxtail
-------------------------------------------- % control -------------------------------------- 1000s/A cwt/A
1 83 b2 95 a 100 a 75 bc 100 a 60 bc 83 ab 104 390
2 98 a 99 a 100 a 96 ab 100 a 69 abc 80 ab 126 461
3 100 a 100 a 100 a 100 a 100 a 80 ab 98 a 120 469
4 98 a 100 a 100 a 93 ab 95 a 75 abc 88 ab 108 420
5 95 a 100 a 100 a 93 ab 95 a 73 abc 83 ab 110 449
6 83 b 80 b 100 a 60 c 100 a 54 c 82 ab 111 400
7 100 a 95 a 100 a 93 ab 100 a 70 abc 75 b 126 438
8 100 a 93 ab 100 a 90 ab 100 a 83 ab 78 b 111 419
9 100 a 100 a 100 a 98 a 100 a 75 abc 90 ab 113 465
10 99 a 99 a 100 a 88 ab 100 a 73 abc 94 ab 118 427
11 98 a 100 a 100 a 88 ab 100 a 63 abc 75 b 128 477
12 98 a 100 a 100 a 88 ab 100 a 80 ab 90 ab 119 431
13 100 a 100 a 100 a 100 a 100 a 85 a 88 ab 113 427
14 0 c 0 c 0 b 0 d 0 b 0 d 0 c 105 370
C.V. (%) 8 10 0 17 4 24 16 13 14
Weed Comp3. 5 1 3 1.6 1.8 0.9 0.9

1See Table 65 for treatment definitions.

2Values in the same column followed by the same letter are not significantly different at the 0.05 level. Columns without letters indicate that there were no significant differences between values in that column.

3Weed competition given in number of weeds per square foot.

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