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
ONION WEED CONTROL STUDY, 2001
Richard Greenland
Table 42. Weed control treatments
Table 43. Onion stand and injury, and weed ratings for June 4 and June 21
Table 44. Onion stand and injury, and weed ratings for July 4 and Sept. 7, and days to half-down
Weed control is difficult in onions because onions do not compete well with weeds and few herbicides are available for onion production. Late emerging weeds are not shaded by the onions and grow vigorously. Although they don’t reduce yield much, they interfere with harvest. In this experiment we looked at several new herbicides and herbicide combinations for use in onions, along with some new application timings for labeled herbicides.
MATERIALS AND METHODS
Soil: |
Maddock sandy loam; pH=7.5; 2.0% organic matter; soil-P was very high; soil-K was high; soil-S was very low. |
Previous crops: |
2000 - tomato, pepper and potato; 1999 - pumpkin and winter squash; 1998 - field corn. |
Seedbed preparation: |
Disked April 25. Multiweeded (field cultivated) twice; once on April 25 to incorporate fertilizer and once lightly on May 1 to smooth the seedbed. |
Planting: |
Direct seeded Teton onions (200,000 seeds/acre) on May 1 with a Stanhay vegetable planter modified to drill a barley cover crop (1 bu/acre, 6-inch rows) between and parallel to the onion rows. Onions were planted in paired rows (3" apart), with the paired rows on 16" centers. Sprayed Poast + Dash (1.5 pt + 1 pt/acre) on May 30 to kill the barley cover crop. |
Plots: |
Plots were 17 ft long by 6 ft wide on 8 ft centers (giving a 2-ft check strip between plots). The study had 4 reps. |
Fertilizer: |
On April 19, broadcast 10 lbs N/acre and 50 lbs P2O5/acre as 10-50-0 and 18 lbs N/acre and 20 lbs S/acre as 21-0-0-24. Sprayed 50 lbs N/acre as 28-0-0 on April 25. Fertigated 35 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 42. In addition, all plots were hand weeded on July 9 and 10. Sprayed all plots with Poast + Dash (1.5 pt + 1 pt/acre on May 30) to kill barley cover crop. Sprayed Bravo (1.5 pts/acre on July 12 and 3 pt/acre on July 17 and Aug 27), Ridomil MZ72 (2.5 lb/acre on July 24 and Aug 16) and Maneb (2 lb/acre on Aug 8) for disease control. No insect control needed. |
Harvest: |
Not harvested due to vandalism |
Axiom and Nortron were weak on lambsquarters and nightshades, but this may have been due, at least in part, to the late application. When combined with Buctril + Goal, both Axiom and Nortron gave good to excellent control of all weeds in the study. Valor gave good to excellent weed control. Valor and Axiom reduced onion stand. Buctril, applied just before onions emerged gave excellent weed control. Authority had the best weed control late in the season, but it injured onions and delayed their maturity. A lower rate of Authority may reduce injury while still controlling weeds.
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Table 42. Treatments for the Oakes Irrigation Research Site 2001 onion weed control study
Treatment number |
Herbicides |
Rate (product/acre) |
Application timing1 |
1 |
Prowl + Prowl |
1.5 pt + 1.5 pt |
POST1 + POST5 |
2 |
Dacthal + Prowl |
8 lbs + 1.5 pt |
PRE2 + POST5 |
3 |
Valor§ |
1.5 oz |
PRE1 |
4 |
Valor§ |
3.0 oz |
PRE1 |
5 |
Valor |
1.5 oz |
PRE1 |
6 |
Nortron§ |
1 lb |
PRE1 |
7 |
Nortron§ |
2 lb |
PRE1 |
8 |
Nortron |
1 lb |
PRE1 |
9 |
Axiom§ |
0.43 lb |
PRE1 |
10 |
Axiom§ |
0.85 lb |
PRE1 |
11 |
Axiom |
0.43 lb |
PRE1 |
12 |
Buctril + Prowl + Prowl |
1 pt + 1 pt + 1.5 pt |
PRE3 + POST1 + POST5 |
13 |
Prowl + Dual II Magnum |
1.5 pt + 1 pt |
POST1 + POST5 |
14 |
Prowl + Outlook |
1.5 pt + 1 pt |
POST1 + POST5 |
15 |
Prowl + Authority |
1.5 pt + 4 oz |
POST1 + POST5 |
16 |
Prowl |
1.5 pt |
POST1 |
17 |
Prowl + Prowl |
1.5 pt + 1.5 pt |
PRE + POST5 |
1PRE1 - after onions & barley were planted (May 9); PRE2 - just after barley emerged (May 11);
PRE3 - just before onions emerged (May 14); POST1 - just after onions emerged (May 29);
POST2 - when barley cover crop was 9 inches tall (May 30); POST3 - when onions had 1 true
leaf (June 4); POST4 - when onions had two true leaves (June 12); POST5 - when onions had
3 true leaves (June 19); POST6 - when onions had 4 to 5 true leaves (June 29).
All treatments were sprayed with 20 gal of undiluted 28% N solution at POST3, and Poast (1.5 pts) + surfactant at POST2 (to kill barley cover crop). Except for those marked with a “§”, all treatments received Buctril + Goal (1.5 + 0.6 pts) at POST4 and POST6.
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Table 43. Onion stand and injury, and weed ratings for June 4 and June 21.
Trt no.1 |
June 4 ratings |
June 21 ratings |
||||||||||
onion stand |
onion injury |
redroot pigweed |
lambs- quarters |
nightshade |
onion stand |
onion injury |
redroot pigweed |
lambs- quarters |
nightshade |
|||
hairy |
E. black |
hairy |
E.black |
|||||||||
|
-------------------------------------------------------------- 0 to 102 -------------------------------------------------------------- |
|||||||||||
1 |
5.5 a-d3 |
1.0 abc |
9.0 |
7.3 f |
7.5 d-g |
6.5 c-g |
6.3 bcd |
2.0 ef |
8.8 bcd |
9.5 ab |
10.0 a |
10.0 a |
2 |
6.0 a-d |
0.3 ab |
9.3 |
9.5 ab |
9.3 abc |
8.8 ab |
7.0 a-d |
1.0 bcd |
9.3 abc |
10.0 a |
10.0 a |
10.0 a |
3 |
4.3 cde |
1.5 c |
10.0 |
8.8 a-e |
10.0 a |
9.5 a |
5.5 def |
0.0 a |
8.8 bcd |
7.3 c-f |
10.0 a |
9.5 ab |
4 |
3.8 de |
1.3 bc |
10.0 |
9.3 abc |
9.5 ab |
8.8 ab |
4.5 efg |
0.5 abc |
9.5 ab |
8.8 abc |
10.0 a |
9.8 ab |
5 |
5.5 a-d |
1.0 abc |
9.8 |
8.5 b-f |
10.0 a |
9.8 a |
5.8 cde |
1.5 def |
10.0 a |
9.8 ab |
10.0 a |
10.0 a |
6 |
5.8 a-d |
0.3 ab |
9.8 |
8.0 c-f |
8.8 a-d |
8.8 ab |
7.0 a-d |
0.3 ab |
9.5 ab |
6.5 f |
8.3 b |
8.0 c |
7 |
7.3 ab |
0.0 a |
9.8 |
9.0 a-d |
8.8 a-d |
9.0 a |
7.3 abc |
1.0 bcd |
10.0 a |
7.0 def |
9.0 b |
9.0 abc |
8 |
7.8 a |
0.5 abc |
10.0 |
9.0 a-d |
8.0 b-f |
7.8 a-e |
7.5 ab |
1.8 def |
10.0 a |
9.8 ab |
10.0 a |
10.0 a |
9 |
5.3 bcd |
0.5 abc |
10.0 |
8.5 b-f |
6.3 g |
8.3 a-d |
4.0 fg |
0.0 a |
8.8 bcd |
6.8 ef |
3.5 d |
9.0 abc |
10 |
2.5 e |
2.8 d |
10.0 |
9.5 ab |
6.8 fg |
8.5 abc |
3.5 g |
0.3 ab |
10.0 a |
8.5 a-d |
4.8 c |
8.8 bc |
11 |
4.3 cde |
0.0 a |
9.5 |
8.5 b-f |
6.8 fg |
8.3 a-d |
4.5 efg |
3.0 g |
10.0 a |
8.3 b-e |
10.0 a |
10.0 a |
12 |
7.0 ab |
0.8 abc |
9.5 |
9.0 a-d |
9.5 ab |
8.5 abc |
6.8 a-d |
1.3 cde |
10.0 a |
10.0 a |
10.0 a |
10.0 a |
13 |
6.3 abc |
0.3 ab |
9.5 |
8.0 c-f |
6.8 fg |
6.3 d-g |
6.8 a-d |
1.8 def |
8.5 bcd |
9.3 ab |
10.0 a |
10.0 a |
14 |
7.5 ab |
0.5 abc |
10.0 |
7.8 def |
8.5 a-e |
5.8 efg |
7.5 ab |
1.8 def |
9.3 abc |
8.8 abc |
10.0 a |
10.0 a |
15 |
5.5 a-d |
0.0 a |
9.0 |
8.0 c-f |
8.0 b-f |
4.5 g |
6.8 a-d |
2.3 fg |
10.0 a |
9.3 ab |
10.0 a |
10.0 a |
16 |
6.3 abc |
0.3 ab |
8.8 |
8.5 b-f |
7.8 c-g |
6.8 b-f |
7.3 abc |
2.0 ef |
7.8 d |
9.8 ab |
10.0 a |
10.0 a |
17 |
7.3 ab |
0.0 a |
8.3 |
10.0 a |
9.0 a-d |
8.5 abc |
7.0 a-d |
1.3 cde |
8.5 bcd |
10.0 a |
10.0 a |
10.0 a |
Prob. |
0.004 |
0.02 |
0.50 |
0.012 |
<.0001 |
<.0001 |
<.0001 |
<.0001 |
0.0004 |
<.0001 |
<.0001 |
0.025 |
C.V. |
16 |
77 |
8 |
11 |
6 |
9 |
19 |
51 |
9 |
13 |
7 |
8 |
1See Table 42 for treatments.
2Ratings: 0 is no effect (no weed control or no crop injury); 10 is complete weed or crop kill. For stand, 10 is a perfect stand and 0 is no plants.
3Values in the same column followed by the same letter are not significantly different at the 0.05 level. If no letters follow values in a column then there were no significant differences between values in that column.
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Table 44. Onion stand and injury, and weed ratings for July 4 and Sept. 7, and days to half-down.
Trt no.1 |
July 4 ratings |
July 9 weeding times2 |
Sept. 7 ratings |
Days to half-down |
||||||
onion stand |
onion injury |
redroot pigweed |
lambs- quarters |
hairy nightshade |
E. black nightshade |
redroot pigweed |
common purslane |
|||
|
----------------------------------- 0 to 103 ----------------------------------- |
minutes |
------ 0 to 103 ------ |
|
||||||
1 |
6.3 bcd4 |
1.0 bc |
8.8 bcd |
10.0 a |
10.0 a |
10.0 a |
3.3 a |
7.3 bc |
9.8 a |
129 b |
2 |
7.0 abc |
0.5 abc |
9.3 a-d |
10.0 a |
10.0 a |
10.0 a |
4.5 a |
7.8 ab |
10.0 a |
126 ab |
3 |
6.3 bcd |
0.0 a |
8.3 d |
6.5 fg |
9.8 a |
8.5 b |
19.3 b |
6.3 bcd |
7.3 bcd |
128 b |
4 |
4.5 e |
0.0 a |
9.5 abc |
8.5 bcd |
10.0 a |
10.0 a |
11.5 ab |
8.3 ab |
8.5 ab |
128 b |
5 |
6.0 cd |
0.0 a |
9.3 a-d |
9.3 abc |
10.0 a |
10.0 a |
4.9 a |
8.0 ab |
8.8 ab |
127 b |
6 |
6.8 abc |
0.0 a |
9.3 a-d |
6.0 g |
7.0 c |
6.8 c |
48.3 d |
6.3 bcd |
6.5 cd |
133 cd |
7 |
7.0 abc |
1.0 bc |
9.0 a-d |
6.8 efg |
8.0 b |
7.5 bc |
35.8 c |
6.8 bc |
7.3 bcd |
128 b |
8 |
8.0 a |
0.8 abc |
10.0 a |
9.8 ab |
10.0 a |
10.0 a |
7.0 a |
8.3 ab |
9.3 a |
129 b |
9 |
3.8 ef |
0.8 abc |
8.5 cd |
6.8 efg |
3.0 d |
8.8 ab |
68.5 e |
4.0 d |
5.5 de |
129 bcd |
10 |
2.5 f |
0.3 ab |
9.0 a-d |
7.8 def |
2.5 d |
8.5 b |
51.0 d |
5.0 cd |
4.5 e |
133 d |
11 |
5.0 de |
1.3 c |
8.8 bcd |
8.0 cde |
10.0 a |
10.0 a |
9.2 ab |
6.8 bc |
6.5 cd |
122 a |
12 |
7.0 abc |
0.5 abc |
9.8 ab |
10.0 a |
10.0 a |
10.0 a |
3.3 a |
8.0 ab |
9.5 a |
127 b |
13 |
7.0 abc |
1.0 bc |
9.0 a-d |
9.8 ab |
10.0 a |
10.0 a |
7.5 a |
7.8 ab |
9.3 a |
126 ab |
14 |
7.5 ab |
0.8 abc |
9.0 a-d |
9.5 ab |
10.0 a |
10.0 a |
6.5 a |
7.5 b |
9.8 a |
128 b |
15 |
6.3 bcd |
5.8 d |
10.0 a |
10.0 a |
10.0 a |
10.0 a |
2.9 a |
10.0 a |
10.0 a |
>150 e |
16 |
7.0 abc |
0.8 abc |
6.8 e |
10.0 a |
10.0 a |
10.0 a |
9.2 ab |
7.3 bc |
8.3 abc |
129 bc |
17 |
7.3 abc |
1.0 bc |
8.8 bcd |
10.0 a |
10.0 a |
10.0 a |
5.8 a |
7.8 ab |
9.5 a |
125 ab |
Prob. |
<.0001 |
<.0001 |
<.0001 |
<.0001 |
<.0001 |
<.0001 |
<.0001 |
0.011 |
<.0001 |
<.0001 |
C.V. |
16 |
77 |
8 |
11 |
6 |
9 |
51 |
23 |
15 |
2 |
1See Table 42 for treatments.
2Average time to weed a 6 by 17 ft. plot.
3Ratings: 0 is no effect (no weed control or no crop injury); 10 is complete weed or crop kill. For stand, 10 is a perfect stand and 0 is no plants.
4Values in the same column followed by the same letter are not significantly different at the 0.05 level.
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