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, 2000
Richard Greenland
Table 40. Herbicide treatments
Table 41. Weed control ratings
Table 42. Onion injury and characteristics of onions
Table 43. Number and yield of onions
Weed control is difficult in onions because onions do not compete well with weeds and few herbicides are available for onion production. A critical time for weed control is between onion emergence and the two true leaf stage. Weeds emerge and grow, but Buctrile and Goal cannot be applied during this time because they will injure the onions. There is no herbicide currently labeled to control weeds during this time. Often times the weeds have grown too large for Buctril and Goal to effectively control them when the herbicides are applied at the two true leaf stage. 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 study we looked at 28% N as a possible herbicide when applied at the one leaf stage of onions. We also looked at some new herbicides, not yet labeled for use in onions, for weed control (especially late emerging weeds) and crop injury determinations.
MATERIALS AND METHODS
Soil: | Maddock sandy loam; pH=7.1; 2.5% organic matter; soil-P and soil-K were very high; soil-S was high. |
Previous crops: | 1999 - pumpkin and squash; 1998 - field corn; 1997 - broccoli and cabbage. |
Seedbed preparation: | Disked on 29 October 1999. Multiweeded (field cultivated) on April 5 and April 17 to incorporate fertilizer and smooth the seedbed. |
Planting: | Direct seeded Teton onions (200,000 seeds/acre) on April 17 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. Planted onions in paired rows (3 inches apart), with the paired rows on 16-inch centers. Sprayed Fusilade + nonionic surfactant (12 oz/acre + 1 qt/50 gal) on May 18 to kill the barley cover crop. |
Plots: | Plots were 17 ft long by 6 ft (four paired rows plus wheel track) wide with a two foot border between plots. The study had 4 reps. |
Fertilizer: | On April 4, broadcast 18 lbs N/acre and 20 lbs S/acre as 21-0-0-24. Applied 50 lbs N/acre as 28-0-0 on April 12. Fertigated 35 lbs N/acre as 28-0-0 on June 27 and July 14. See Table 40 for additional N applications. |
Irrigation: | Overhead sprinkler irrigation as needed. |
Pest control: | In addition to the 28% N and other herbicides used in the treatments (See Table 40), weeds were controlled with Fusillade (1 pt/acre + non-ionic surfactant on May 18) and Buctril + Goal (1.5 + 0.6 pt/acre on May 31). We sprayed with Kocide (1.5 lbs/acre on July 20), Manzate (3 lb/acre on July 12 and 2 lb/acre on July 7, July 26, and Aug 2), and Bravo 500 (3 pt/acre on Aug 9 and 2 pt/acre on Aug 26) to control diseases. No insect control needed. |
Harvest: | Pulled onions Sept 14 to Sept 24 (approximately two weeks after half-down dates). Onions were allowed to dry in the field until September 29 when they were bagged and moved to a shed. The onions were graded Nov. 15 to Nov. 20. |
Authority controlled pigweed, hairy nightshade, and lambsquarters early in the season, but lost control later. Frontier controlled pigweed early, but did not control late emerging pigweed unless a second application was made. It gave fair to poor (early and late) control of lambsquarters and fair to good control of hairy nightshade. Dual controlled pigweed, lambsquarters, and hairy nightshade. When applied at the two-true-leaf stage of onions, Dual controlled weeds throughout the rest of the season. A later application of Dual was not advantageous. The 28% N solution at 20 and 25 gal/acre increased pigweed control slightly and maybe not significantly. It did not help control lambsquarters and hairy nightshade.
Authority killed onions when applied preemergence. The destruction was slightly less when the application was delayed until just before onions emerged. In a border plot Authority injured onions less when we sprayed Authority when the onions had one true leaf, but the injury was still unacceptable. Spraying Authority when the onions have two to three true leaves is an option we will evaluate in the future. Frontier sprayed just after onions emerged caused slight damage, reduced onion plant height (at the 2X rate), slightly delayed maturity, and reduced onion stand, but did not reduce yield. Frontier or Dual, at the standard rates, sprayed when onions had two true leaves or later did not effect onion stand or yields. The 28% N solution did not affect onion stand or yield.
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Table 40. Herbicide treatments for the Oakes Irrigation Research Site 2000 onion weed control study.
Treatment number | Herbicide(s) | Rate | Application timing1 |
1 | Authority + 28% N | 4 oz + 20 gal | PRE1 + POST2 |
2 | Authority + 28% N | 8 oz + 20 gal | PRE1 + POST2 |
3 | Authority + 28% N | 4 oz + 20 gal | PRE2 + POST2 |
4 | Authority + 28% N + Frontier | 4 oz + 20 gal + 1 pt | PRE1 + POST2 + POST3 |
5 | Prowl + urea | 1.5 pts + 130 lbs | POST1 + POST2 |
6 | Prowl + 28% N + urea | 1.5 pts + 15 gal + 33 lbs | POST1 + POST2 + POST2 |
7 | Prowl + 28% N | 1.5 pts + 20 gal | POST1 + POST2 |
8 | Prowl + 28% N | 1.5 pts + 25 gal | POST1 + POST2 |
9 | Prowl + 28% N | 3 pts + 20 gal | POST1 + POST2 |
10 | Prowl + 28% N + Prowl | 1.5 pts + 20 gal + 1.5 pts | POST1 + POST2 + POST3 |
11 | Prowl + 28% N + Prowl | 1.5 pts + 20 gal + 1.5 pts | POST1 + POST2 + POST4 |
12 | Frontier + 28% N | 1 pt + 20 gal | POST1 + POST2 |
13 | Frontier + 28% N | 2 pts + 20 gal | POST1 + POST2 |
14 | Frontier + 28% N + Frontier | 1 pt + 20 gal + 1 pt | POST1 + POST2 + POST4 |
15 | Prowl + 28% N + Frontier | 1.5 pts + 20 gal + 1 pt | POST1 + POST2 + POST3 |
16 | Prowl + 28% N + Frontier | 1.5 pts + 20 gal + 1 pt | POST1 + POST2 + POST4 |
17 | Prowl + 28% N + Dual | 1.5 pts + 20 gal + 2 pts | POST1 + POST2 + POST3 |
18 | Prowl + 28% N + Dual | 1.5 pts + 20 gal + 4 pts | POST1 + POST2 + POST3 |
19 | Prowl + 28% N + Dual | 1.5 pts + 20 gal + 2 pt | POST1 + POST2 + POST4 |
1PRE1 was on April 21 (after planting, but before barley or onions emerged); PRE2 was on May 1 (after barley emerged but before onions emerged); POST1 was on May 5 (just after onions emerged); POST2 was on May 18 (urea) or May 22 and 23 (28% N) (onions had one true leaf); POST3 was on June 8 (onions had 3 true leaves); POST4 was on June 22 (onions had 4 to 5 true leaves). All plots sprayed with Fusilade (1 pt/acre + non-ionic surfactant) on May 18 (barley was 6 to 7 inches tall), and Buctril + Goal (1.5 + 0.6 pt/acre) on May 31 (onions had 2 true leaves).
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Table 41. Weed control ratings1 in the Oakes Irrigation Research Site 2000 onion weed control study.
Treatment2 number | Redroot pigweed | Hairy nightshade | Lambsquarters | |||||
May 15 | May 31 | Aug 16 | May 15 | May 31 | Aug 16 | May 15 | May 31 | |
1 | 10.0 a3 | 10.0 a | 7.8 d-g | 10.0 a | 10.0 a | 8.8 bc | 10.0 a | 10.0 a |
2 | 10.0 a | 10.0 a | 8.6 a-e | 10.0 a | 10.0 a | 8.8 bc | 10.0 a | 10.0 a |
3 | 10.0 a | 10.0 a | 8.3 b-f | 10.0 a | 10.0 a | 8.8 c | 10.0 a | 10.0 a |
4 | 10.0 a | 10.0 a | 7.9 d-g | 10.0 a | 10.0 a | 9.3 abc | 10.0 a | 10.0 a |
5 | 7.5 de | 8.3 d | 7.5 efg | 8.0 bc | 8.3 cd | 10.0 a | 8.8 bc | 8.0 c |
6 | 7.5 de | 8.5 cd | 7.0 g | 7.8 bc | 9.3 ab | 9.8 a | 9.3 b | 8.8 bc |
7 | 8.3 b-e | 9.0 bcd | 7.5 efg | 8.0 bc | 9.5 ab | 10.0 a | 9.3 b | 9.3 ab |
8 | 8.3 b-e | 9.3 abc | 8.0 c-g | 7.3 c | 9.5 ab | 9.8 a | 9.3 b | 9.0 abc |
9 | 7.3 de | 9.3 abc | 7.8 d-g | 7.8 bc | 9.5 ab | 9.8 a | 9.0 bc | 9.3 ab |
10 | 8.3 cde | 8.8 bcd | 8.0 c-g | 7.8 bc | 9.8 ab | 9.3 abc | 8.5 cd | 8.3 bc |
11 | 7.5 de | 9.5 ab | 8.5 a-e | 8.3 bc | 9.5 ab | 10.0 a | 9.3 b | 9.3 ab |
12 | 9.8 ab | 9.5 ab | 7.0 g | 8.3 bc | 7.5 d | 9.3 abc | 8.0 d | 5.8 d |
13 | 9.3 abc | 10.0 a | 7.1 fg | 8.8 b | 7.8 d | 9.3 abc | 8.5 cd | 6.0 d |
14 | 9.5 abc | 10.0 a | 9.4 ab | 8.3 bc | 7.8 d | 9.8 a | 9.0 bc | 6.3 d |
15 | 8.5 a-d | 9.5 ab | 8.8 a-d | 8.0 bc | 10.0 a | 9.6 ab | 9.0 bc | 9.3 ab |
16 | 8.3 b-e | 8.8 bcd | 9.4 ab | 8.0 bc | 9.5 ab | 10.0 a | 8.8 bc | 8.8 bc |
17 | 7.0 e | 9.3 abc | 8.8 a-d | 8.3 bc | 9.8 ab | 10.0 a | 9.0 bc | 9.0 ab |
18 | 8.0 cde | 9.3 abc | 9.1 abc | 8.0 bc | 9.5 ab | 10.0 a | 9.0 bc | 9.0 abc |
19 | 7.8 de | 8.5 cd | 9.5 a | 7.8 bc | 9.0 bc | 10.0 a | 9.0 bc | 8.5 bc |
C.V. (%) | 6 | 3 | 5 | 5 | 4 | 3 | 2 | 4 |
Probability | <.0001 | <.0001 | <.0001 | <.0001 | <.0001 | 0.016 | <.0001 | <.0001 |
1Ratings are from 0 to 10 with 0 equal to plot covered with large, vigorous weeds and 10 equal to no weeds in plot.
2See Table 40 for a description of the treatments.
3Values in the same column followed by the same letter are not significantly different at the 0.05 level. Data transformed using a square root transformation for analysis. Values presented as untransformed means.
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Table 42. Onion injury and characteristics of onions in the Oakes Irrigation Research Site 2000 weed control study.
Treatment1 number | Onion injury | Plant height June 27 | Growth stage June 27 | Days to half-down | Single centered | Uni- formity |
Overall appearance | |
May 15 | May 31 | |||||||
------ 1 to 10 ----- | inches | # of true leaves | % | 1 to 5 | 1 to 10 | |||
1 | 9.0 d2 | 9.3 d | 0.0 e | 0.0 c | --3 | 27 d | 3.0 d | 7.3 c |
2 | 9.3 d | 9.1 d | 0.0 e | 0.0 c | --3 | 19 d | 3.4 a-d | 7.5 bc |
3 | 6.5 c | 5.8 c | 7.0 d | 3.6 b | --3 | 25 d | 3.1 cd | 7.8 ab |
4 | 9.3 d | 9.5 d | 0.0 e | 0.0 c | --3 | 75 abc | 3.0 d | 7.3 c |
5 | 0.0 a | 0.0 a | 18.0 ab | 6.4 a | 120 a | 70 abc | 4.0 a | 8.0 a |
6 | 0.0 a | 0.3 a | 17.8 ab | 6.4 a | 120 a | 65 bc | 3.8 ab | 8.0 a |
7 | 0.0 a | 0.3 a | 17.5 ab | 6.5 a | 120 a | 85 ab | 3.9 ab | 8.0 a |
8 | 0.5 ab | 0.3 a | 16.8 ab | 6.3 a | 122 ab | 80 ab | 3.8 ab | 7.8 ab |
9 | 0.3 a | 0.0 a | 17.0 ab | 6.4 a | 121 ab | 80 ab | 3.9 ab | 8.0 a |
10 | 0.0 a | 0.3 a | 17.0 ab | 6.5 a | 120 a | 85 ab | 3.8 ab | 8.0 a |
11 | 0.0 a | 0.5 ab | 17.0 ab | 6.5 a | 121 ab | 55 c | 3.8 ab | 8.0 a |
12 | 0.5 ab | 0.5 ab | 16.8 ab | 6.1 a | 123 bc | 65 bc | 3.9 ab | 7.8 ab |
13 | 1.3 b | 1.3 b | 14.5 c | 5.9 a | 125 c | 75 abc | 3.8 ab | 8.0 a |
14 | 0.8 ab | 0.5 ab | 17.0 ab | 6.3 a | 121 a | 75 abc | 3.4 bcd | 8.0 a |
15 | 0.0 a | 0.5 ab | 17.0 ab | 6.3 a | 121 ab | 70 abc | 4.0 a | 8.0 a |
16 | 0.3 a | 0.5 ab | 18.0 ab | 6.4 a | 120 a | 65 bc | 3.9 ab | 8.0 a |
17 | 0.0 a | 0.3 a | 18.3 a | 6.5 a | 121 a | 80 ab | 3.9 ab | 8.0 a |
18 | 0.0 a | 0.8 ab | 16.3 bc | 6.3 a | 122 ab | 90 a | 3.6 abc | 8.0 a |
19 | 0.0 a | 0.8 ab | 17.3 ab | 6.4 a | 120 a | 85 ab | 3.8 ab | 8.0 a |
C.V. (%) | 33 | 30 | 10 | 11 | 1 | 22 | 10 | 3 |
Probability | <.0001 | <.0001 | <.0001 | <.0001 | 0.007 | 0.0001 | 0.0016 | 0.0013 |
1See Table 40 for a description of the treatments.
2Values in the same column followed by the same letter are not significantly different at the 0.05 level.
3Onions in these treatments did not go down.
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Table 43. Number and yield of onions in the Oakes Irrigation Research Site 2000 weed control study.
Treatment number1 | Number of onion bulbs harvested | Onion bulb yield (by size) | ||||||
> 3" | 2¼ to 3" | < 2¼ | Total | > 3" | 2¼ to 3" | < 2¼ | Total | |
---------------- 1000s per acre ---------------- | -------------------- cwt per acre ---------------- | |||||||
1 | 2 e2 | 2 g | 0 c | 5 g | 14 f | 6 g | 0 c | 23 e |
2 | 1 e | 0 g | 0 c | 2 g | 11 f | 2 g | 0 c | 16 e |
3 | 24 d | 13 g | 4 c | 45 f | 184 de | 47 g | 7 c | 251 d |
4 | 1 e | 1 g | 0 c | 3 g | 7 f | 4 g | 0 c | 15 e |
5 | 40 bc | 107 a | 38 ab | 203 ab | 236 b-e | 405 a | 58 ab | 737 a |
6 | 42 b | 101 abc | 36 ab | 196 abc | 246 b-e | 376 abc | 55 ab | 714 ab |
7 | 34 bcd | 109 a | 39 ab | 206 a | 196 cde | 397 ab | 58 ab | 698 abc |
8 | 42 bc | 100 abc | 41 ab | 203 abc | 246 b-e | 371 abc | 63 a | 716 ab |
9 | 42 b | 104 ab | 40 ab | 206 a | 251 b-e | 390 ab | 61 a | 745 a |
10 | 28 cd | 94 a-e | 38 ab | 180 cde | 167 e | 346 a-d | 60 ab | 611 c |
11 | 43 ab | 88 b-e | 39 ab | 186 a-e | 250 b-e | 324 cde | 58 ab | 666 abc |
12 | 45 ab | 77 def | 31 b | 171 de | 277 abc | 298 de | 48 ab | 663 abc |
13 | 56 a | 63 f | 30 b | 164 e | 353 a | 226 f | 44 b | 648 abc |
14 | 47 ab | 86 cde | 32 b | 181 b-e | 287 ab | 317 cde | 49 ab | 690 abc |
15 | 44 ab | 105 ab | 37 ab | 203 ab | 262 bcd | 392 ab | 58 ab | 747 a |
16 | 43 ab | 105 ab | 35 ab | 202 abc | 256 bcd | 391 ab | 51 ab | 741 a |
17 | 36 bcd | 106 a | 40 ab | 205 a | 206 b-e | 393 ab | 58 ab | 694 abc |
18 | 42 b | 76 ef | 45 a | 186 a-d | 256 bcd | 271 ef | 61 a | 631 bc |
19 | 44 ab | 95 a-d | 38 ab | 194 a-d | 258 bcd | 338 bcd | 56 ab | 686 abc |
C.V.(%) | 28 | 17 | 26 | 11 | 29 | 16 | 25 | 13 |
Probability | <.0001 | <.0001 | <.0001 | <.0001 | <.0001 | <.0001 | <.0001 | <.0001 |
1See Table 40 for a description of the treatments.
2Values in the same column followed by the same letter are not significantly different at the 0.05 level.
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