APPLICATION TIMING AND TANK MIXES WITH ROUNDUP ORIGINALMAX OVER-THE-TOP OF ROUNDUP READY SUGAR BEETS

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1 APPLICATION TIMING AND TANK MIXES WITH ROUNDUP ORIGINALMAX OVER-THE-TOP OF ROUNDUP READY SUGAR BEETS Joel Felix and Joey Ishida Malheur Experiment Station Oregon State University Ontario, OR, 2007 Introduction Weed control is considered a major challenge in many, if not all, crops and production systems. Sugar beets are especially vulnerable to weeds due to their poor competitiveness at the early growth stage, before their leaves cover the ground. Emerging sugar beets are small, lack vigor, and take about days to cover the ground. This is why sugar beet growers have traditionally used preplant or preemergence (PRE) herbicides to control weeds that emerge together with the crop. The introduction of Roundup Ready (RR) sugar beets presents an opportunity for growers to employ a total postemergence (POST) weed management program. If root yields are to be maximized, the total POST weed management program will require diligent monitoring of weed cohorts that emerge in succession. The proponents of soilapplied herbicides argue that it is a sound way to minimize weed biotype selection and a viable way to provide sustainable weed control. A field study was conducted at the Maiheur Experiment Station in Ontario, Oregon to determine crop response to herbicide tank mixtures of conventional herbicides with RoundUp OriginalMax to control weeds in RR sugar beets. Materials and Methods A trial was conducted during 2007 in a field that had been ripped, moldboard plowed, disked several times, and bedded during fall of the previous year. The beds were 22 inches wide and the field was bed harrowed during spring following application of Roundup OriginalMax at 18 fi oz/acre to control all emerged weeds before planting. The field had previously been planted to wheat, and had a ph of 7.65, 2.1 percent organic matter, CEC (cation exchange capacity) of 18.5, and the predominant soil was an Owyhee silt loam. The study was laid out following a randomized complete block design with plots measuring 4 rows wide by 30 ft and four replications. Sugar beet seeds, variety 'BTSCTOI RRO7',.were planted on April 19, 2007 using tractor-mounted flexi-planter units with double-disc furrow openers and cone seeders fed from a spinner divider that uniformly distributed the seeds within the row. Sugar beet seeds were dropped at the rate of 8 seeds/ft of row and later thinned to 8 inches between plants within a row. 144

2 The study was sidedressed with Temik 15G at 10 lbs/acre on May 22 to control sugar beet maggot and the rows were recorrugated to allow free movement of irrigation water. The field was furrow irrigated for 24 hours to move the insecticide into the sugar beet seedling root zone. The study was initially irrigated for 24 hours every 2 weeks starting April 20 and weekly starting May 23 until September 18, Cultivation and corrugation to open up irrigation furrows was done three times before leaf canopy closure. All herbicide treatments were applied using a 002 backpack sprayer calibrated to deliver 20 gal/acre with a boom fitted with four TeeJet EVS 8002 flat fan nozzles. Treatments that included Nortron PRE (application timing code A) were applied on April 11 and incorporated as required by the label. Other herbicide application timings were May 4, 2007 (B = sugar beet at the cotyledon stage); May 10 (C = sugar beet at the 2-leaf stage); May 25 (D = sugar beet at the 4-leaf stage); May 25 (E = sugar beet at the 6-leaf stage); and June 16 (H = sugar beet at canopy closure). Enable fungicide at 8 fi oz/acre with 1 percent v/v crop oil concentrate plus sulfur at 4 lb/acre and boron at 0.10 lb/acre were applied using an aerial applicator on June 30. Additional aerial application of fungicides/insecticides on July 14, August 1, and August 22, 2007 delivered Headline at 12 oz/acre, Topsin M at lib/acre, and Asana at 9.6 oz/acré plus Enable at 8 oz/acre, respectively. A final weed evaluation was done on October 9, 2007 before the foliage was flailed and the crowns removed with rotating knives on tractor-mounted equipment. Sugar beets were mechanically harvested on October 12, 2007 and a beet weight for each plot was recorded before transporting samples to the Snake River Sugar factory for sugar analysis. The sugar beet weight from each plot was multiplied by a factor of 0.90 to correct for tare. Sugar concentrations were determined by multiplying measured sucrose by 0.98 to estimate the sugar that would have been lost to respiration if the beets had been stored in a pile. The percent sugar extraction was calculated using the formula: Ext = [(1,255.2 * Cond) -(15,000 * Sug) -6,185]! Sug * ( * Cond) Where Ext is percent sugar extraction, Cond is the electrical conductivity in mmho, and Sug is the sucrose concentration in percent. The data were subjected to analysis of variance to determine treatment differences using the least significant difference at P = Results Roundup Ready sugar beet responded differently to soil-applied herbicides followed by POST application of Roundup OriginalMax tank-mixes with other products (Tables 1-5). There was a noticeable reduction in the level of control for kochia, pigweed species, 145

3 common lambsquarters, and hairy nightshade when Nortron at 3 pt/acre was applied PRE followed by a combination of Progress Ultra plus Upbeet plus Stinger at 0.77 pt/acre plus 1.5 oz/acre pius 4 oz/acre, respectively, and the micro-rate program. Visual evaluations done on May 25, 2007 (14 days after application of treatment code C) indicated a reduction in sugar beet growth for POST treatments that included a combination of Progress Ultra plus Upbeet plus Stinger at 0.77 pt/acre plus 1.5 oz/acre plus 4 oz/acre, respectively (Table 2). The sugar beet leaves were lime yellow and the plants were relatively shorter compared to those treated with other herbicide combinations. The reduction in growth and yellowing of the leaves was still visible during the evaluation on July 3, 2007 (Tables 4 and 5). The observed reduction in growth for these treatments (11 and 12) culminated in a significant reduction in sugar beet root yield and gross sugar (lbs/acre) (Table 6). Weed control was generally excellent for treatments 1-10 and the hand-weeded control (Tables 1-5). Kochia, pigweed species, and common lambsquarters control ranged from 90 to 99 percent regardless of the treatment (Tables 1-5). Reduced hairy nightshade control was observed for treatment 12 throughout the season. Barnyardgrass control was very low for treatments 11 and 12 starting July 3, 2007 (Tables 4 and 5). Sugar beet root yield ranged from 53 to 55.9 ton/acre for treatments 1-10 and the hand-weeded control, but was reduced to 29.5 and 43.9 ton/acre for treatments 11 and 12, respectively (Table 6). The trend for root yield reduction was consistent with the level of growth reduction and weed control that was observed during the growing season. As a result, there was a significant drop in the estimated recoverable sugar yield. 146

4 Table 1. Roundup Ready sugar beet response and weed control on May 17, 2007 (7 days after C timing) with postemergence application of Roundup OriginalMax with and without soil residual herbicides, Malheur Experiment Station, Oregon State University, Ontario, OR, Visual crop growth reduction Kochia Pigweed Common Hairy species lambsquarters nightshade Treatment Rate Timing* (0-100%) Roundup OriginalMax 1.33 pt/acre C;E;H NIS 0.4 pt/acre Roundup OiginalMax 1.33 pt/acre E + Arnmoaium sulfate 3.2 pt/acre + Outlook 1.12 pt/acre Roundup OriginalMax 1.33 pt/acre C Roundup OtiginalMax 1.33 pt/acre C Outlook 18 oiacre + Ammoniurn sulfate 32 pt/acre Roundup OnginalMax 1.33 pt/acre C Select 8 oz/acre Nortron 4 pt/acre A Roundup OnginalMax 1 33 pt/acre C;E,H E + Nortron 2 25 pt/acre E Nortron 3 pt/acre A Roundup OriginalMax 1.33 pt/acre C;H + Anmonium sulfate 32 pt/acre Roundup OriginatMax 1.33 pt/acre E Arnmonium sulfate 3.2 pt/acre + Nortron 32 ozlacre Progress Ultra 3 oz/acre B:C;D;E Nortron 3 pt/acre A Progress Ultra 0.77 pt/acre C + Upbeet 0.5 ozlacre + Stinger 4 ozlacre Handweeded control Untreated Check LSD (0.05) 1 NS NS I CV *Timing A = preplant incorporated; B = cotyledon stage; C = 2-leaf sugar beet; D = 4-leaf sugar beet; E = 6-leaf sugar beet, F = 8-leaf sugar beet; 0 = 10- to 12-leaf sugar beet; H = canopy closure.

5 Table 2. Roundup Ready sugar beet response and weed control on May 25, 2007 (14 days after emergence) with postemergence application of Roundup OriginalMax with and without soil residual herbicides, Maiheur Experiment Station, Oregon State University, Ontario, OR, Visual crop Pigweed Common Hairy growt Kcc fta species lambsquarters nightshade reduction (0-100%) Treatment Rate Timing* + Arnmonium sulfate 3.2 pt/acre +NtS 0.4 pt/acre + Arnmonlurn sulfate 3.2 pt/acre + Arnmonium sulfate 3.2 pt/acre + Outlook 1.12 pt/acre Roundup OriginalMax 1.33 pt/acre C Roundup OriginalMax 1.33 pt/acre C Amrnonium sulfate 3.2 pt/acre + Outlook 18 ozfacre Roundup OriginalMax 1 33 pt/acre E;l-1 Roundup OriginalMax 1.33 pt/acre C Select 8 oz/acre Nortron 4 pt/acre A Roundup OriginalMax 1.33 pt/acre C,E;H f Ammonium sulfate 3.2 pt/acre Roundup OriginalMax 1.33 pt/acre C;H E + Nortron 2.25 pt/acre E Nortron 3 pt/acre A Roundup OnginalMax 1 33 pt/acre C;H Ammonium sulfate 3.2 pt/acre + Nortron 32 oz/acre Progress Ultra 3 oz/acre B:C;D;E Nortron 3 pt/acre A Progress Ultra 0.77 pt/acre C + Upbeet 0.5 oz/acre + Stinger 4 az/acre Handweeded control Untreated check LSD (P 0.05) 5 3 NS 5 CV *Timing A = preplant incorporated; B = cotyledon stage; C = 2-leaf sugar beet; D = 4-leaf sugar beet; E 6-leaf sugar beet, F = 8-leaf sugar beet; G = 10- to 12-leaf sugar beet; H = canopy closure

6 Table 3. Roundup Ready sugar beet response and weed control on June 1, 2007 (36 days after emergence) with postemergence application of Roundup OriginalMax with and without soil residual herbicides, Malheur Experiment Station, Oregon State University, Ontario, OR, Visual Crop Pigweed Common Hairy Growth Kochia species lambsquarters nightshade Reduction Treatment Rate Timinq* (0-100%) +NIS 04 pt/acre + Ammonium sulfate 32 pt/acre oundup OriginalMax 1.33 pt/acre C;H AmOniUm sulfate 3.2 pt/acre Roundup OriginalMax t33 pt/acre E + Outlook 1.12 pt/acre Roundup OriginalMax 1.33 pt/acre C RoundupOrigina1Mox 133 pt/acre C AmmoniUrn sulfate 3.2 ptlacre Outlook 18 oz/acre Roundup OriginalMax I.33 pt/acre E;H + Ammonlurn sulfate 3.2 pt/acre Roundup OriginalMax 1.33 pt/acre C Select 8 ozlacre Nortron 4 pt/acre A Roundup OriginalMax 1.33 pt/acre C,E,H Roundup OriginalMax 1.33 pt/acre C;H E + Nortron 2 25 pt/acre E Nortron 3 pt/acre A Roundup OriginalMax 1.33 pt/acre C;H + Ammonlum sulfate 3.2 pt/acre Roundup OtiginalMax 1.33 pt/acre E + NOTLrOn 32 oz/acre Progress Ultra 3 oz/acre B:C;D;E Upbeet oz/acre + Stinger 1.28 ozlacre Nortron 3 pt/acre A Progress Ultra 0.77 pt/acre C + Upbeet 0 5 az/acre + Stinger 4 az/acre Handweeded control Untreated check LSD (0.05) CV *Tlming A = preplant incorporated; B = cotyledon stage; C = 2-leaf sugar beet; D = 4-leaf sugar beet; E = 6-leaf sugar beet, F = 8-leaf sugar beet; G = 10- to 12-leaf sugar beet; H = canopy closure. 149

7 Table 4. Roundup Ready sugar beet response and weed control on July 3, 2007 (67 days after emergence) with postemergence application of Roundup OriginalMax with and without soil residual herbicides, Maiheur Experiment Station, Oregon State University, Ontario, OR, P Pigweed Common Hairy Barnyard Kochia reduction species lambsquarters nightshade grass Treatment Rate Timinq* (0-100%) Roundup OriginalMax 1.33 pt/acre C;E;H Ammonium sulfate 32 pt/acre Roundup OriginalMax 1.33 pt/acre C,E;F NIS 0.4 pt/acre 99 Roundup OriginalMax 1 33 pt/acre C,H Amrnonium sulfate 3.2 pt/acre Roundup OriginalMax 1 33 pt/acre E + Outlook 112 pt/acre Roundup OriginalMax 1.33 pt/acre C Roundup OriginalMax 1.33 pt/acre C Arnmbnium sulfate 3.2 pt/acre + Outlook 18 az/acre Roundup OriginalMax 1.33 pt/acre C Select 8 ozlacre Nortron 4 pt/acre A Roundup OriginatMax 1.33 pt/acre C;E,H + Ammonium sulfate 32 pt/acre Roundup OriginalMax 1.33 pt/acre C;H E + Nortron 2.25 pt/acre E Nortron 3 pt/acre A RoundupOtigina1Max 1.33 pt/acre C;H + Nortron 32 oz/acre Progress Ultra 3 oz/acre B:C;D;E Methylated Oil 15 mill Nortron 3 pt/acre A pt/acre C Progress Ultra + Upbeet 0.5 ozlacre Handweeded control Untreated check LSD(P 0.05) CV *Timing A = preplant incorporated; B = cotyledon stage; C = 2-leaf sugar beet; D = 4-leaf sugar beet; E 6-leaf sugar beet, F 8-leaf sugar beet; G = 10- to 12-leaf sugar beet; H = canopy closure. 150

8 Table 5. Roundup Ready sugar beet response and weed control on October 9, 2007 (165 days after emergence) with postemergence application of Roundup OriginalMax with and without soil residual herbicides, Malheur Experiment Station, Oregon State University, Ontario, OR, Lady's Pigweed Common Hairy Barnyard K OC ha I thumb species lambsquarters nightshade grass Treatment Rate Timing* (0-100%) Roundup OriginalMax 1.33 pt/acre C;E;H Ammonium sulfate 3.2 pt/acre Roundup OriginalMax 1.33 pt/acre C;E;H NIS 04 pt/acre Roundup OriginalMax 1.33 pt/acre C;H Roundup OriginalMax 1.33 pt/acre C;H )mmonium sulfate 3.2 pt/acre Roundup OrtginalMax 1.33 pt/acre E + Mmonium sulfate 3.2 pt/acre + Outlook 1.12 pt/acre Roundup OriginalMax 1.33 pt/acre C Roundup QriginalMax 1 33 pt/acre C Ammoniurn sulfate 32 pt/acre + Outlook 18 ozlacre Roundup OnginalMax 1.33 pt/acre E;H + Arnmonium sulfate 3.2 pt/acre Roundup OriginalMax 1.33 pt/acre C Select 8 oz/acre Nortron 4 pt/acre A Roundup OriginalMax 1.33 pt/acre C;E;H +Ammoaium sulfate 3.2 pt/acre Roundup OriginalMax 1.33 pt/acre C;H E + Nortron 2.25 pt/acre E Nortron 3 pt/acre A Roundup OriginalMax 1.33 pt/acre C;H Roundup OiiglnalMax 1.33 pt/acre E + Ammonium sulfate 3,2 pt/acre + Nortron 32 ozfacre Progress Ultra 3 oz/acre B:C;D;E Nortron 3 pt/acre A Progress Ultra 0.77 pt/acre C + Upbeet 0.5 oziacre Handweeded control Untreated check LSD (P= 0.05) CV *Timing A = preplant incorporated; B = cotyledon stage; C = 2-leaf sugar beet; D = 4-leaf sugar beet; E = 6-leaf sugar beet, F = 8-leaf sugar beet; G = 10- to 12-leaf sugar beet; H = canopy closure 151

9 Table 6. Roundup Ready5 sugar beet root yield and yield components in response to postemergence application of Roundup OriginalMax with and without soil residual herbicides, Malheur Experiment Station, Oregon State University, Ontario, OR, Sugar Conduc- Estimated recoverable Root yield Extraction content tivity sugar Treatment Rate Timinq* ton/acre % mmho % lb/acre lb/ton Roundup OriginalMax 1.33 pt/acre C;E;H , Roundup OriginalMax 1.33 pt/acre C,E;H NIS 0.4 pt/acre Roundup OriginalMax 1.33 pt/acre C;H , Roundup OriginalMax 1.33 pt/acre C;H , , Amrnonium sulfate 3.2 pt/acre Roundup OriginatMax 1.33 pt/acre E + Amrnonium sulfate 3.2 pt/acre + Outlook 112 pt/acre Roundup OriginalMax 1.33 pt/acre C , Ammonium sulfate 3.2 pt/acre Roundup OriginalMax 1.33 pt/acre C 54, , Ammonium sulfate 3.2 pt/acre + Outlook 18 oz/acre Roundup OriginalMax 1.33 pt/acre C Select 8 oz/acre Nortron 4 pt/acre A 54 'r i , Roundup OriginalMax 1 33 pt/acre C,E,H + Arnmoniurn sulfate 3.2 pt/acre Roundup OriginalMax 1.33 pt/acre C,H , Nortron 2.25 pt/acre Nortrón 3 pt/acre A Roundup OriginalMax 1.33 pt/acre C;H + Arnmonium sulfate 3.2 pt/acre + Nortron 32 oz/acre Progress Ultra 3 oz/acre B:C;D;E , Nortron 3 pt/acre A , Progress Ultra 0 77 pt/acre C + tipbeet 0.5 ozlacre + Stinger 4 ozlacre Handweeded control , Untreated check LSD (P= 0.05) ,361 NS CV *Timing A = preplant incorporated; B = cotyledon stage; C = 2-leaf sugar beet; D 4-leaf sugar beet; E = 6-leaf sugar beet, F = 8-leaf sugar beet; G = 10- to 12-leaf sugar beet; H = canopy closure. 152