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Corey V. Ransom, Charles A. Rice, and Joey K. Ishida
Malheur Experiment Station
Oregon State University
Ontario, OR, 2002
Introduction
Weed control is essential for the production of marketable onions. Weed control in onion is difficult compared to many crops because of the lack of a complete crop canopy. Combinations of soil-active and postemergence herbicides are required to improve overall weed control. Weed control research is important in identifying potential herbicides and management strategies to improve weed control in onion production.
General Procedures
Trials were conducted at the Malheur Experiment Station to evaluate experimental and registered herbicides for weed control and onion tolerance. The effect of spray volume on weed control and onion tolerance was also evaluated. Trials were conducted under furrow irrigation. Blanket applications were applied with a four-wheeler-mounted sprayer calibrated to deliver 10 gal/acre at 30 psi. All other herbicide treatments were applied with a CO2-pressurized backpack sprayer calibrated to deliver 40 gal/acre at 30 psi. On March 29, onions (cv. 'Vaquero', Sunseeds, Morgan Hill, CA) were planted at a 3.7-inch spacing in double rows on 22-inch beds. Plots were four rows wide and 27 ft long and treatments were arranged in a randomized complete block design with four replicates. Lorsban was applied in a 6-inch band over each row at 3.7 oz/1,000 ft of row. Onions were sidedressed with N at 75 lb/acre as urea on May 22 and a second time on June 5. Registered insecticides and fungicides were applied for thrip and downy mildew control. Weed control and onion injury were evaluated throughout the season. Onions were harvested September 16 and graded by size on September 25. Data were analyzed using analysis of variance and means were separated using a protected least significant difference (LSD) at the 5 percent level (0.05).Herbicide Application Timing for Pigweed Control in Onion
Buctril and Goal were applied at different rates and application timings alone and in combination to determine the most effective treatments for control of pigweed (Powell amaranth and redroot pigweed), common lambsquarters, and hairy nightshade. All treatments included a preemergence application of Roundup (0.375 lb ai/acre). Postemergence treatments were applied to one-, two-, three-, and five-leaf onions. At the five-leaf timing all treatments received an application of Goal (0.25 lb ai/acre). Herbicides and rates differed for applications to one-, two-, and three-leaf onions.Prowl and Outlook for Weed Control in Onion
The soil-active herbicides Prowl, Prowl H2O, and Outlook were evaluated for crop injury and weed control in onion. All plots received a preemergence application of Roundup at 0.375 lb ai/acre. Prowl and Prowl H2O were compared at rates of 0.62 and 1.0 lb ai/acre applied to flag-leaf onions and to two-leaf onions at 0.62 lb ai/acre with Buctril (0.25 lb ai/acre) plus Outlook (0.5 lb ai/acre). Postemergence applications of Outlook were applied either as a split application to two- and three-leaf onions or a single application at 0.66 or 0.84 lb ai/acre to two-leaf onions. Split applications of Outlook were applied twice at 0.5 lb ai/acre or at 0.66 and 0.33 lb ai/acre to two-leaf and three-leaf onions, respectively. Outlook was applied with Buctril (0.125 or 0.25 lb ai/acre), Goal (0.125 or 0.25 lb ai/acre), Prowl (0.5 or 0.62 lb ai/acre), or Prowl H2O (0.62 lb ai/acre). All treatments consisting of four applications received an application of Goal at 0.25 lb ai/acre applied at the four-leaf stage.Soil-active Herbicides for Weed Control in Onion
The soil-active herbicides Dacthal, Prowl, and Valor were evaluated for crop injury and weed control in onion. Various rates of Prowl and Dacthal were applied alone and in combination with Roundup. All herbicide-treated plots received a preemergence application of Roundup (0.375 lb ai/acre) applied with Prowl (0.6, 0.75, or 0.8 lb ai/acre) and/or Dacthal (5.0, 7.5, or 10.0 lb ai/acre) on April 12. The two-leaf applications consisted of Buctril (0.125 or 0.25 lb ai/acre) plus Poast (0.1 lb ai/acre); Valor (0.063 or 0.094 lb ai/acre) with and without crop oil concentrate (COC) (1.0 percent v/v); or Buctril (0.25 lb ai/acre) plus Valor (0.094 lb ai/acre) applied on May 17. Buctril (0.25 lb ai/acre), Goal (0.25 lb ai/acre), and Poast (0.1 lb ai/acre) were applied to three-leaf onions on May 25 and Goal (0.25 lb ai/acre) plus Poast (0.1 lb ai/acre) were applied to four-leaf onions on May 30.Herbicide Application Timing for Pigweed Control in Onion
In general, treatments with Goal (0.156 lb ai/acre) applied to one-leaf onions or those where Buctril plus Goal were applied to two- and three-leaf onions provided the best overall weed control (Table 1). Pigweed control was increased when Goal was applied with Buctril to one-leaf onions compared to Buctril alone. Treatments including Buctril at the two-leaf application timing provided significantly (P < 0.05) greater control of hairy nightshade than those without Buctril. The treatment including Outlook plus Goal applied to two-leaf onions provided similar pigweed and hairy nightshade control compared to those treatments having Buctril plus Goal applied at the same application timing. However, common lambsquarters control was greater from treatments where Buctril plus Goal were applied to two-leaf onions compared with Goal plus Outlook. Hairy nightshade control on June 29 (30 days after treatment [DAT]) was similar among treatments having Buctril or Outlook applied at the two-leaf application timing. Due to deteriorating weed control over time, late season weed control evaluations and onion yields were not taken for this trial.Prowl and Outlook for Weed Control in Onion
Crop injury ranged from 4 to 17 percent on June 12 (18 DAT) (Table 3). Treatments including a four-leaf application of Goal caused similar injury on June 12. Weed control with treatments including comparisons between Prowl and Prowl H2O were not different (Table 2). Common lambsquarters control was not different (P < 0.05) among herbicide treatments on either evaluation date. Prowl (1.0 lb ai/acre) followed by applications of Buctril plus Outlook to two-leaf onions, Goal plus Outlook to three-leaf onions, and Goal applied to four-leaf onions were the only herbicide treatments that provided less than 60 percent hairy nightshade control on August 6. In general, the highest marketable and total onion yields came from those treatments where Goal was applied to two- and three-leaf onions or Outlook was applied at 0.66 lb ai/acre to two-leaf onions (Table 3).Soil-active Herbicides for Weed Control in Onion
Onion injury ranged from 12 to 30 percent on May 23 (6 days after the two-leaf application) and was greatest in plots receiving a two-leaf application of Buctril at 0.25 lb ai/acre plus Valor at 0.094 lb ai/acre (Table 5). However, by June 12 (13 DAT) crop injury associated with this treatment was similar to or less than all other herbicide treatments. Pigweed control was 100 percent on both June 29 (30 DAT) and August 6 (68 DAT) with the treatment including Dacthal (7.5 lb ai/acre) plus Prowl (0.6 lb ai/acre) preemergence followed by Buctril (0.25 lb ai/acre) plus Valor (0.094 lb ai/acre) applied to two-leaf onions (Table 4). In general, greater common lambsquarters control was achieved when Buctril was applied to two-leaf onions compared to Valor alone with or without COC. However, the greatest common lambsquarters control was observed with Buctril at 0.25 lb ai/acre plus Valor at 0.094 lb ai/acre applied to two-leaf onions following a preemergence application of Roundup (0.375 lb ai/acre) plus Dacthal (7.5 lb ai/acre) and Prowl (0.6 lb ai/acre). Hairy nightshade control was greatest on August 6 when Valor at 0.094 lb ai/acre was included in the herbicide program. Treatments with Valor at 0.094 lb ai/acre provided 93 and 98 percent hairy nightshade control on August 6. All herbicide-treated plots provided marketable and total onion yields greater than the untreated control (Table 5). The herbicide program including the combination of Buctril (0.25 lb ai/acre) plus Valor (0.094 lb ai/acre) applied to two-leaf onions provided greater colossal, super colossal, marketable, and total onion yields than all other treatments. The high onion yield associated with this treatment is directly related to season-long weed control that was 98 percent or greater for all species.Preemergence Nortron and Prowl for Weed Control in Onion
On June 13 (14 DAT) onion injury from herbicide treatments ranged from 14 to 16 percent and was significantly (P < 0.05) greater than the untreated control (Table 7). Pigweed control was greater with Prowl applied at 1.5 lb ai/acre than at 0.75 lb ai/acre on both June 13 and August 6 (68 DAT) (Table 6). The addition of preemergence Nortron at both 1.0 and 2.0 lb ai/acre increased pigweed control over Prowl applied preemergence at 0.75 lb ai/acre and the Roundup-only preemergence treatment on August 6. Common lambsquarters control was greater on August 6 with preemergence applications of Prowl at 1.5 lb ai/acre, Nortron at 2.0 lb ai/acre, and all Prowl plus Nortron combinations compared to Roundup alone preemergence. The treatment including preemergence Nortron at 2.0 lb ai/acre and Prowl at 0.75 lb ai/acre was the only treatment that provided greater than 90 percent control of hairy nightshade on August 6.Spray Volume Effects on Weed Control and Onion Injury
Increasing onion injury with Valor plus NIS from increasing spray volume was observed on all three evaluation dates (Table 8). This increase in injury may be attributed to the spray volume effects or to the increasing surfactant load as the NIS rate was applied at 0.25 percent of the spray gallonage for all three spray volumes. Crop injury from Goal applications was not affected by spray volume. Crop injury from Buctril decreased with increasing spray volume as observed on June 13 (14 DAT). By June 29 (30 DAT), only Valor plus NIS applied at 30 and 60 gal/acre displayed injury greater than the untreated control. Common lambsquarters control 30 DAT with Valor plus NIS increased from 69 percent applied at 10 gal/acre to 92 percent applied at 60 gal/acre spray volume (Table 8). The opposite was true for Buctril; common lambsquarters control significantly decreased from 97 percent at 10 gal/acre down to 60 percent at 60 gal/acre spray volume. Due to deteriorating weed control over time, late-season weed control evaluations and onion yields were not taken for this trial.| Weed control | ||||||||||
| Pigweed species‡ | Common lambsquarters | Hairy nightshade | ||||||||
| Treatment* | Rate | Timing† | 6-12 | 6-29 | 6-12 | 6-29 | 6-12 | 6-29 | ||
| lb ai/acre | Crop stage | ----------------------------------------------- % ---------------------------------------------- | ||||||||
| Untreated control | -- | -- | 0 | 0 | 0 | 0 | 0 | 0 | ||
| Buctril Buctril Buctril Goal |
0.05 0.125 0.25 0.25 |
1-leaf 2-leaf 3-leaf 5-leaf |
84 | 69 | 94 | 88 | 96 | 92 | ||
| Buctril+Goal Buctril Buctril Goal |
0.05+0.063 0.125 0.25 0.25 |
1-leaf 2-leaf 3-leaf 5-leaf |
92 | 79 | 93 | 86 | 94 | 91 | ||
| Goal Buctril Buctril Goal |
0.156 0.25 0.25 0.25 |
1-leaf 2-leaf 3-leaf 5-leaf |
96 | 91 | 98 | 95 | 97 | 96 | ||
| Buctril Goal Buctril Goal |
0.05 0.31 0.25 0.25 |
1-leaf 2-leaf 3-leaf 5-leaf |
91 | 83 | 90 | 76 | 89 | 79 | ||
| Buctril Buctril+Goal Buctril Goal |
0.05 0.125+0.156 0.25 0.25 |
1-leaf 2-leaf 3-leaf 5-leaf |
92 | 81 | 91 | 82 | 96 | 97 | ||
| Buctril Buctril+Goal Buctril Goal |
0.05 0.125+0.31 0.25 0.25 |
1-leaf 2-leaf 3-leaf 5-leaf |
96 | 89 | 95 | 83 | 97 | 96 | ||
| Buctril Buctril+Goal Buctril+Goal Goal |
0.05 0.25+0.156 0.125+0.156 0.25 |
1-leaf 2-leaf 3-leaf 5-leaf |
97 | 92 | 97 | 90 | 98 | 100 | ||
| Buctril Goal+Outlook Buctril+Goal Goal |
0.05 0.156+0.656 0.25+0.156 0.25 |
1-leaf 2-leaf 3-leaf 5-leaf |
96 | 88 | 93 | 75 | 95 | 95 | ||
| Buctril Goal Buctril+Goal Goal |
0.05 0.156 0.125+0.156 0.25 |
1-leaf 2-leaf 3-leaf 5-leaf |
91 | 77 | 88 | 71 | 89 | 74 | ||
| LSD (0.05) | 5 | 8 | 4 | 7 | 6 | 15 | ||||
| Weed control | ||||||||||
| Pigweed species‡ | Common lambsquarters | Hairy nightshade | ||||||||
| Treatment* | Rate | Timing† | 6-12 | 8-6 | 6-12 | 8-6 | 6-12 | 8-6 | ||
| lb ai/acre | Crop stage | ---------------------------------------%--------------------------------------- | ||||||||
| Untreated control | -- | -- | 0 | 0 | 0 | 0 | 0 | 0 | ||
| Prowl Buctril+Prowl+Outlook Buctril+Outlook Goal |
0.62 0.25+0.6 +0.5 0.25+0.5 0.25 |
flag 2-leaf 3-leaf 4-leaf |
92 | 65 | 98 | 100 | 97 | 96 | ||
| Prowl H2O Buctril+ProwlH2O+Outlook Buctril+Outlook Goal |
0.62 0.25+0.62+0.5 0.25+0.5 0.25 |
flag 2-leaf 3-leaf 4-leaf |
89 | 53 | 98 | 100 | 98 | 88 | ||
| Prowl Buctril+Outlook Goal Goal |
1.0 0.25+0.66 0.25 0.25 |
flag 2-leaf 3-leaf 4-leaf |
96 | 70 | 98 | 99 | 96 | 84 | ||
| Prowl H2O Buctril+Outlook Goal Goal |
1.0 0.25+0.66 0.25 0.25 |
flag 2-leaf 3-leaf 4-leaf |
95 | 78 | 98 | 100 | 93 | 66 | ||
| Prowl Buctril Goal Goal |
1.0 0.25 0.25 0.25 |
flag 2-leaf 3-leaf 4-leaf |
96 | 64 | 98 | 95 | 97 | 80 | ||
| Prowl Buctril+Goal+Outlook Buctril+Goal+Outlook Goal |
1.0 0.125+0.125+0.5 0.25+0.125+0.5 0.25 |
flag 2-leaf 3-leaf 4-leaf |
94 | 76 | 98 | 98 | 98 | 99 | ||
| Prowl Buctril+Outlook Goal+Outlook Goal |
1.0 0.25+0.5 0.25+0.5 0.25 |
flag 2-leaf 3-leaf 4-leaf |
96 | 73 | 98 | 98 | 93 | 58 | ||
| Prowl Buctril+Outlook Goal Goal |
1.0 0.25+0.84 0.25 0.25 |
flag 2-leaf 3-leaf 4-leaf |
92 | 70 | 98 | 96 | 94 | 83 | ||
| Prowl Buctril+Goal+Outlook Goal+Prowl+Outlook |
1.0 0.25+0.25+0.66 0.25+0.5+0.33 |
flag 2-leaf3-leaf |
96 | 76 | 98 | 96 | 97 | 88 | ||
| LSD (0.05) | 5 | 15 | NS | 6 | 4 | 21 | ||||
| Onion yield‡ | |||||||||
| Treatment | Rate | Timing* | Onion injury† | Medium | Jumbo | Colossal | Super colossal | Total | Marketable |
| lb ai/acre | Crop stage | % | --------------------------------- cwt/acre -------------------------------- | ||||||
| Untreated control | -- | -- | 0 | 4 | 1 | 0 | 0 | 14 | 4 |
| Prowl Buctril+Prowl+Outlook Buctril+Outlook Goal |
0.62 0.25+0.62+0.5 0.25+0.5 0.25 |
flag 2-leaf 3-leaf 4-leaf |
14 | 40 | 507 | 142 | 26 | 737 | 716 |
| Prowl H2O Buctril+ProwlH2O+Outlook Buctril+Outlook Goal |
0.62 0.25+0.62+0.5 0.25+0.5 0.25 |
flag 2-leaf 3-leaf 4-leaf |
16 | 41 | 329 | 92 | 37 | 514 | 499 |
| Prowl Buctril+Outlook Goal Goal |
1.0 0.25+0.66 0.25 0.25 |
flag 2-leaf 3-leaf 4-leaf |
16 | 34 | 443 | 117 | 20 | 621 | 614 |
| Prowl H2O Buctril+Outlook Goal Goal |
1.0 0.25+0.66 0.25 0.25 |
flag 2-leaf 3-leaf 4-leaf |
15 | 21 | 569 | 149 | 30 | 776 | 769 |
| Prowl Buctril Goal Goal |
1.0 0.25 0.25 0.25 |
flag 2-leaf 3-leaf 4-leaf |
13 | 24 | 470 | 123 | 16 | 643 | 633 |
| Prowl Buctril+Goal+Outlook Buctril+Goal+Outlook Goal |
1.0 0.125+0.125+0.5 0.25+0.125+0.5 0.25 |
flag 2-leaf 3-leaf 4-leaf |
17 | 38 | 611 | 168 | 24 | 860 | 842 |
| Prowl Buctril+Outlook Goal+Outlook Goal |
1.0 0.25+0.5 0.25+0.5 0.25 |
flag 2-leaf 3-leaf 4-leaf |
17 | 26 | 434 | 164 | 38 | 676 | 661 |
| Prowl Buctril+Outlook Goal Goal |
1.0 0.25+0.84 0.25 0.25 |
flag 2-leaf 3-leaf 4-leaf |
17 | 23 | 451 | 153 | 38 | 677 | 664 |
| Prowl Buctril+Goal+Outlook Goal+Prowl+Outlook |
1.0 0.25+0.25+0.66 0.25+0.5+0.33 |
flag 2-leaf 3-leaf |
4 | 23 | 541 | 169 | 51 | 796 | 783 |
| LSD (0.05) | 3 | NS | 221 | 83 | NS | 246 | 244 | ||
| Weed control | ||||||||
| Pigweed species† | Common lambsquarters | Hairy nightshade | ||||||
| Treatment | Rate | Timing* | 6-29 | 8-06 | 6-29 | 8-06 | 6-29 | 8-06 |
| lb ai/acre | Crop stage | ---------------------------------------- % ---------------------------------------- | ||||||
| Untreated control | -- | -- | 0 d | 0 d | 0 | 0 | 0 | 0 |
| Roundup+Prowl Buctril+Poast Buctril+Goal+Poast Goal+Poast |
0.375+0.75 0.125+0.1 0.25+0.125+0.1 0.25+0.1 |
PRE 2-leaf 3-leaf 4-leaf |
89 bc | 67 c | 95 | 81 | 86 | 38 |
| Roundup+Dacthal Buctril+Poast Buctril+Goal+Poast Goal+Poast |
0.375+10.0 0.125+0.1 0.25+0.125+0.1 0.25+0.1 |
PRE 2-leaf 3-leaf 4-leaf |
87 c | 67 c | 87 | 68 | 87 | 53 |
| Roundup+Dacthal+Prowl Buctril+Poast Buctril+Goal+Poast Goal+Poast |
0.375+5.0+0.6 0.125+0.1 0.25+0.125+0.1 0.25+0.1 |
PRE 2-leaf 3-leaf 4-leaf |
92 bc | 81 bc | 94 | 79 | 84 | 30 |
| Roundup+Dacthal+Prowl Buctril+Poast Buctril+Goal+Poast Goal+Poast |
0.375+5.0+0.8 0.125+0.1 0.25+0.125+0.1 0.25+0.1 |
PRE 2-leaf 3-leaf 4-leaf |
89 bc | 77 bc | 93 | 82 | 84 | 15 |
| Roundup+Dacthal+Prowl Buctril+Poast Buctril+Goal+Poast Goal+Poast |
0.375+7.5+0.6 0.125+0.1 0.25+0.125+0.1 0.25+0.1 |
PRE 2-leaf 3-leaf 4-leaf |
94 b | 86 b | 93 | 77 | 84 | 16 |
| Roundup+Dacthal+Prowl Valor Buctril+Goal+Poast Goal+Poast |
0.375+7.5+0.6 0.063 0.25+0.125+0.1 0.25+0.1 |
PRE 2-leaf 3-leaf 4-leaf |
85 c | 64 c | 84 | 51 | 91 | 72 |
| Roundup+Dacthal+Prowl Valor Buctril+Goal+Poast Goal+Poast |
0.375+7.5+0.6 0.094 0.25+0.125+0.1 0.25+0.1 |
PRE 2-leaf 3-leaf 4-leaf |
89 bc | 75 bc | 89 | 58 | 99 | 93 |
| Roundup+Dacthal+Prowl Valor+COC Buctril+Goal+Poast Goal+Poast |
0.375+7.5+0.6 0.063 + 1.0% v/v 0.25+0.125+0.1 0.25+0.1 |
PRE 2-leaf 3-leaf 4-leaf |
93 b | 84 b | 83 | 58 | 94 | 73 |
| Roundup+Dacthal+Prowl Buctril+Valor Buctril+Goal+Poast Goal+Poast |
0.375+7.5+0.6 0.2 +0.094 0.25+0.125+0.1 0.25+0.1 |
PRE 2-leaf 3-leaf 4-leaf |
100 a | 100 a | 100 | 98 | 100 | 98 |
| LSD (0.05) | -- | -- | 8 | 18 | 7 | 32 | ||
| Onion injury | Onion yield‡ | ||||||||||
| Treatment* | Rate | Timing† | 5-23 | 6-12 | Medium | Jumbo | Colossal | Super colossal | Marketable | Total | |
| lb ai/acre | Crop stage | ------ % ------ | -------------------------------------- cwt/acre -------------------------------------- | ||||||||
| Untreated | -- | -- | 0 | 0 | 1 | 0 | 0 | 0 | 1 | 8 | |
| Prowl Buctril+Poast Buctril+Goal+Poast Goal+Poast |
0.75 0.125+0.1 0.25+0.125+0.1 0.25+0.1 |
PRE 2-leaf 3-leaf 4-leaf |
12 | 14 | 53 | 414 | 67 | 22 | 556 | 567 | |
| Dacthal Buctril+Poast Buctril+Goal+Poast Goal+Poast |
10.0 0.125+0.1 0.25+0.125+0.1 0.25+0.1 |
PRE 2-leaf 3-leaf 4-leaf |
12 | 15 | 77 | 361 | 69 | 11 | 517 | 532 | |
| Dacthal+Prowl Buctril+Poast Buctril+Goal+Poast Goal+Poast |
5.0+0.6 0.125+0.1 0.25+0.125+0.1 0.25+0.1 |
PRE 2-leaf 3-leaf 4-leaf |
15 | 13 | 35 | 353 | 79 | 25 | 492 | 500 | |
| Dacthal+Prowl Buctril+Poast Buctril+Goal+Poast Goal+Poast |
5.0+0.8 0.125+0.1 0.25+0.125+0.1 0.25+0.1 |
PRE 2-leaf 3-leaf 4-leaf |
16 | 14 | 44 | 340 | 53 | 0 | 438 | 447 | |
| Dacthal+Prowl Buctril+Poast Buctril+Goal+Poast Goal+Poast |
7.5+0.6 0.125+0.1 0.25+0.125+0.1 0.25 0.1 |
PRE 2-leaf 3-leaf 4-leaf |
15 | 14 | 56 | 433 | 57 | 8 | 554 | 566 | |
| Dacthal+Prowl Valor Buctril+Goal+Poast Goal+Poast |
7.5+0.6 0.063 0.25+0.125+0.1 0.25+0.1 |
PRE 2-leaf 3-leaf 4-leaf |
16 | 13 | 80 | 250 | 61 | 7 | 397 | 416 | |
| Dacthal+Prowl Valor Buctril+Goal+Poast Goal+Poast |
7.5+0.6 0.094 0.25+0.125+0.1 0.25+0.1 |
PRE 2-leaf 3-leaf 4-leaf |
16 | 14 | 38 | 293 | 91 | 31 | 452 | 470 | |
| Dacthal+Prowl Valor+COC Buctril+Goal+Poast Goal+Poast |
7.5+0.6 0.063+1.0% v/v 0.25+0.125+0.1 0.25+0.1 |
PRE 2-leaf 3-leaf 4-leaf |
18 | 15 | 60 | 350 | 101 | 21 | 533 | 543 | |
| Dacthal+Prowl Buctril+Valor Buctril+Goal+Poast Goal+Poast |
7.5 + 0.6 0.25+0.094 0.25+0.125+0.1 0.25+0.1 |
PRE 2-leaf 3-leaf 4-leaf |
30 | 13 | 15 | 408 | 288 | 97 | 808 | 822 | |
| LSD (0.05) | 5 | 2 | 44 | 164 | 76 | 39 | 195 | 192 | |||
Table 6. Preemergence Nortron and Prowl for weed control in
onions, Malheur Experiment Station, Oregon State University, Ontario,
OR, 2002.
| Weed control† | ||||||||
| Pigweed species‡ | Common lambsquarters | Hairy nightshade | ||||||
| Treatment | Rate | Timing* | 6-13 | 8-06 | 6-13 | 8-06 | 6-13 | 8-06 |
| lb ai/acre | Crop stage | --------------------------------------- % ---------------------------------------- | ||||||
| Untreated control | -- | -- | 0 | 0 | 0 | 0 | 0 c | 0 |
| Prowl Buctril+Goal+Poast Buctril+Goal+Poast Goal+Poast |
0.75 0.125+0.125+0.1 0.25+0.125+0.1 0.25+0.1 |
PRE 2-leaf 3-leaf 4-leaf |
94 | 68 d | 91 | 65 | 93 ab | 67 |
| Prowl Buctril+Goal+Poast Buctril+Goal+Poast Goal+Poast |
1.5 0.125+0.125+0.1 0.25+0.125+0.1 0.25+0.1 |
PRE 2-leaf 3-leaf 4-leaf |
97 | 89 bc | 97 | 83 | 94 ab | 49 |
| Nortron Buctril+Goal+Poast Buctril+Goal+Poast Goal+Poast |
1.0 0.125+0.125+0.1 0.25+0.125+0.1 0.25+0.1 |
PRE 2-leaf 3-leaf 4-leaf |
97 | 94 ab | 95 | 68 | 94 ab | 35 |
| Nortron Buctril+Goal+Poast Buctril+Goal+Poast Goal+Poast |
2.0 0.125+0.125+0.1 0.25+0.125+0.1 0.25+0.1 |
PRE 2-leaf 3-leaf 4-leaf |
97 | 95 ab | 96 | 79 | 93 ab | 51 |
| Buctril+Goal+Poast Buctril+Goal+Poast Goal+Poast |
0.125 + 0.125 +
0.1 0.25 + 0.125 + 0.1 0.25 + 0.1 |
2-leaf 3-leaf 4-leaf |
95 | 81 cd | 93 | 56 | 91 b | 40 |
| Nortron+Prowl Buctril+Goal+Poast Buctril +Goal+Poast Goal+Poast |
1.0 + 0.75 0.125+0.125+0.1 0.25+0.125+0.1 0.25+0.1 |
PRE 2-leaf 3-leaf 4-leaf |
97 | 93 ab | 94 | 82 | 92 b | 48 |
| Nortron+Prowl Buctril+Goal+Poast Buctril+Goal+Poast Goal+Poast |
1.0 + 1.5 0.125+0.125+0.1 0.25+0.125+0.1 0.25+0.1 |
PRE 2-leaf 3-leaf 4-leaf |
97 | 95 ab | 97 | 95 | 96 ab | 72 |
| Nortron+Prowl Buctril+Goal+Poast Buctril+Goal+Poast Goal+Poast |
2.0+0.75 0.125+0.125+0.1 0.25+0.125+0.1 0.25+0.1 |
PRE 2-leaf 3-leaf 4-leaf |
97 | 98 a | 95 | 89 | 98 a | 92 |
| Nortron+Prowl Buctril+Goal+Poast Buctril+Goal+Poast Goal+Poast |
2.0+1.5 0.125+0.125+0.1 0.25+0.125+0.1 0.125+0.1 |
PRE 2-leaf 3-leaf 4-leaf |
98 | 97 ab | 98 | 95 | 96 ab | 73 |
| LSD (0.05) | 3 | -- | 5 | 21 | -- | 42 | ||
Table 7. Onion injury and yield with preemergence Nortron and
Prowl, Malheur Experiment Station, Oregon State University, Ontario,
OR, 2002.
| Onioninjury† | Onion yield | |||||||||
| Treatment | Rate | Timing* | Small | Medium | Jumbo | Colossal | Supercolossal | Marketable | Total | |
| lb ai/acre | Crop stage | % | --------------------------------------- cwt/acre ---------------------------------------- | |||||||
| Untreated control | -- | -- | 0 | 19 | 1 | 0 | 0 | 0 | 1 | 20 |
| Prowl Buctril+Goal+Poast Buctril+Goal+Poast Goal+Poast |
0.75 0.125+0.125+0.1 0.25+0.125+0.1 0.25+0.1 |
PRE 2-leaf 3-leaf 4-leaf |
14 | 9 | 71 | 426 | 88 | 15 | 600 | 612 |
| Prowl Buctril+Goal+Poast Buctril+Goal+Poast Goal+Poast |
1.5 0.125+0.125+0.1 0.25+0.125+0.1 0.25 0.1 |
PRE 2-leaf 3-leaf 4-leaf |
14 | 6 | 60 | 491 | 114 | 21 | 685 | 695 |
| Nortron Buctril+Goal+Poast Buctril+Goal+Poast Goal+Poast |
1.0 0.125+0.125+0.1 0.25+0.125+0.1 0.25+0.1 |
PRE 2-leaf 3-leaf 4-leaf |
14 | 7 | 52 | 446 | 77 | 23 | 598 | 616 |
| Nortron Buctril+Goal+Poast Buctril+Goal+Poast Goal+Poast |
2.0 0.125+0.125+0.1 0.25+0.125+0.1 0.25+0.1 |
PRE 2-leaf 3-leaf 4-leaf |
15 | 9 | 42 | 408 | 140 | 23 | 613 | 626 |
| Buctril+Goal
+Poast Buctril+Goal+Poast Goal + Poast |
0.125+0.125+0.1 0.25+0.125+0.1 0.25+0.1 |
2-leaf 3-leaf 4-leaf |
15 | 8 | 70 | 375 | 53 | 6 | 503 | 517 |
| Nortron+Prowl Buctril+Goal+Poast Buctril+Goal+Poast Goal+Poast |
1.0+0.75 0.125+0.125+0.1 0.25+0.125+0.1 0.25+0.1 |
PRE 2-leaf 3-leaf 4-leaf |
15 | 6 | 40 | 283 | 127 | 63 | 513 | 528 |
| Nortron+Prowl Buctril+Goal+Poast Buctril+Goal+Poast Goal+Poast |
1.0+1.5 0.125+0.125+0.1 0.25+0.125+0.1 0.25+0.1 |
PRE 2-leaf 3-leaf 4-leaf |
15 | 4 | 25 | 435 | 175 | 66 | 700 | 716 |
| Nortron+Prowl Buctril+Goal+Poast Buctril+Goal+Poast Goal+Poast |
2.0+0.75 0.125+0.125+0.1 0.25+0.125+0.1 0.25+0.1 |
PRE 2-leaf 3-leaf 4-leaf |
16 | 3 | 32 | 374 | 191 | 68 | 665 | 680 |
| Nortron+Prowl Buctril+Goal+Poast Buctril+Goal+Poast Goal+Poast |
2.0+1.5 0.125+0.125+0.1 0.125+0.125+0.1 0.125+ 0.1 |
PRE 2-leaf 3-leaf 4-leaf |
15 | 6 | 25 | 415 | 176 | 84 | 700 | 716 |
| LSD (0.05) | 2 | 7 | 41 | 220 | 116 | 56 | 209 | 207 | ||
Table 8. Effect of spray volume on onion injury and weed control with Buctril, Goal, and Valor, Malheur Experiment Station, Oregon State University, Ontario, OR, 2002.
| Onion injury | Weed control‡ | |||||||||
| Treatment* | Rate | Spray volume | Timing† | 5-23 | 6-13 | 6-29 | Pigweed species § | Common lambsquarters | Hairy nightshade | |
| lb ai/acre | gpa | Crop stage | ------------- % ------------- | ---------------------- % ---------------------- | ||||||
| Untreated | -- | -- | -- | 0 | 0 | 0 | 0 | 0 | 0 | |
| Valor + NIS Valor + NIS |
0.094+0.25% v/v 0.094+0.25% v/v |
10 10 |
2-leaf 4-leaf |
26 | 34 | 0 | 86 | 69 | 86 | |
| Valor + NIS Valor + NIS |
0.094+0.25% v/v 0.094+0.25% v/v |
30 30 |
2-leaf 4-leaf |
39 | 41 | 5 | 92 | 76 | 92 | |
| Valor + NIS Valor + NIS |
0.094+0.25% v/v 0.094+0.25% v/v |
60 60 |
2-leaf 4-leaf |
45 | 48 | 10 | 100 | 92 | 100 | |
| Goal Goal |
0.12 0.12 |
10 10 |
2-leaf 4-leaf |
12 | 16 | 0 | 64 | 82 | 13 | |
| Goal Goal |
0.12 0.12 |
30 30 |
2-leaf 4-leaf |
12 | 10 | 0 | 66 | 79 | 34 | |
| Goal Goal |
0.12 0.12 |
60 60 |
2-leaf 4-leaf |
16 | 15 | 0 | 74 | 72 | 42 | |
| Buctril Buctril |
0.125 0.25 |
10 10 |
2-leaf 4-leaf |
14 | 21 | 0 | 28 | 97 | 68 | |
| Buctril Buctril |
0.125 0.25 |
30 30 |
2-leaf 4-leaf |
15 | 11 | 0 | 34 | 76 | 46 | |
| Buctril Buctril |
0.125 0.25 |
60 60 |
2-leaf 4-leaf |
13 | 3 | 0 | 24 | 60 | 73 | |
| LSD (0.05) | 30 | 5 | 8 | 3 | 25 | 17 | 38 | |||
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