Plant Biotechnology: Current and Potential Impact For Improving Pest Management In U.S. Agriculture An Analysis of 40 Case Studies June 2002

Transcription

1 Plant Biotechnology: Current and Potential Impact For Improving Pest Management In U.S. Agriculture An Analysis of 40 Case Studies June 2002 Herbicide Tolerant Soybean Leonard P. Gianessi Cressida S. Silvers Sujatha Sankula Janet E. Carpenter National Center for Food and Agricultural Policy 1616 P Street, NW Washington, DC Phone: (202) Fax: (202) ncfap@ncfap.org Website: Financial Support for this study was provided by the Rockefeller Foundation, Monsanto, The Biotechnology Industry Organization, The Council for Biotechnology Information, The Grocery Manufacturers of America and CropLife America.

2 26. Soybean Herbicide Tolerant Production Thirty-one states have significant soybean acreage (Table 26.1). Soybean production is centered in the Midwest where ten states account for 73% of U.S. acreage and production. The states of Illinois and Iowa each account for more than 10 million acres of soybeans The total value of the soybean crop was $13 billion in 2000, representing approximately 15% of the value of all crops grown in the U.S. Table 26.1 shows production values by state. Figure 26.1 charts average US soybean yields Weed Competition Weeds compete with soybeans for soil moisture, nutrients, sunlight and space in the field. One cocklebur may occupy four to eight square feet of area, thereby reducing the space available for soybean growth. When weeds shade the soybean plant, less sunlight is available for soybean production. Most of the soybean yield reduction from velvetleaf and pigweeds is ascribed to shading by the weed leaves above the soybean canopy. As a result of competing with soybeans, uncontrolled weeds decrease the quantity of soybean seeds produced [44]. The efficiency of operation of harvesting equipment is also reduced by the presence of significant numbers of weeds [45]. The quality of the harvested crop is directly impacted by weeds. Increases in moisture content, foreign matter, and splits have been documented when high levels of weeds are present at harvest [45]. Numerous reports in the literature quantify the effects of full- or partial-season weed interference on soybean seed yields. The data show considerable differences among species in interfering ability. Common cocklebur is the most interfering weed: 1 plant/m 2 depresses soybean yield by 30% while nine plants/m 2 depresses soybean yield by 80%. A 2

3 less competitive weed species for soybeans is giant foxtail: 16 plants/m 2 depresses soybean yield by only 10%. More than thirty plant species infest soybean fields in the major soybean producing areas of the U.S. [46]. Annual broadleaf and grass weeds are major problems. In some areas, perennial grass, broadleaf weeds and sedges are troublesome. Table 26.2 lists the 22 most common weed species in soybean fields in 29 of the major soybean producing states. Ragweed, foxtail, nightshade, lambsquarters, smartweed, and velvetleaf infest more acreage in the Midwest than in the Delta. Morningglory, barnyardgrass, signalgrass, prickly sida, hemp sesbania and sicklepod infest more acreage in the Delta. Cocklebur, johnsongrass, crabgrass and pigweeds are estimated to infest sizable acreages of soybeans in all soybean producing regions. Natural weed populations in most fields are high enough to cause devastating soybean yield losses if left uncontrolled [47]. Loss figures of 50 90% are common for soybeans grown in natural weed infestations [48] [49] [50] [51]. Research has shown that a period of 4 to 6 weeks without weed competition at the beginning of the growing season will allow production of maximum yields under most environmental conditions [47]. Any weed emerging in the crop after this initial weed free period will not compete effectively with soybeans and will not affect yield potential due to the soybean canopy which shades emerging weeds. Similarly, a period of 4 to 6 weeks of weed interference at the beginning of the season usually can be tolerated by soybeans with no significant yield loss provided that the crop is maintained weed free for the remainder of the season [47]. Herbicide Use By the early 1990 s, there were at least 70 registrations for individual herbicides or packaged herbicide mixtures for weed management in soybeans. Table 26.3 tracks herbicide use in soybeans

4 The most widely-used soybean herbicides in 1995 were from the sulfonylurea and imidazolinone chemical classes (imazethapyr, imazaquin, chlorimuron, thifensulfuron). These active ingredients controlled a large number of broadleaf species and when combined with pendimethalin or trifluralin provided effective control of most grass and broadleaf species common in soybean fields in the Midwest [81]. The sulfonylureas and imidazolinones are similar in their mode of action. They are absorbed readily by roots and foliage of plants. Herbicide activity by the sulfonylureas and imidazolinones results from inhibition of the enzyme acetohydroxyacid (AHAS, acetolactate synthase, ALS), which stops the synthesis of three essential amino acids valine, leucine and isoleucine [82]. The widespread use of ALS herbicides quickly led to the development of resistant weed populations. Weeds that evolved resistance to ALS inhibitors evolved altered ALS that is resistant to the herbicide. Resistance to ALS-inhibiting herbicides has been confirmed in kochia, Russian thistle, common waterhemp, Palmer amaranth, common cocklebur, shattercane, giant ragweed and common sunflower [83] [84]. In Missouri and Kansas, common waterhemp resistant to the sulfonylureas and imidazolinones become the principal weed problem in soybeans with over 900,000 acres of soybeans infested [43]. The prevalence of herbicide resistant weeds led to postemergence mixtures of active ingredients for broad range weed control. During the 1990 s soybean growers increasingly shifted towards postemergence herbicide use. By 1995, only 23% of the nation s soybean acreage received only a before or at-plant soil applied herbicide representing a 50% reduction in such treatments between 1990 and The average number of treatments per acre rose from 1.5 in 1990 to 1.7 in 1995 as it was more common for soybean growers to make both an at-plant and postemergence treatment or make two postemergence 4

5 treatments [59]. A steady increase in the number of herbicide active ingredients applied to treated soybean acreage occurred between 1986 and 1995: from 1.4 to 2.7. [60] [61] [62] In 1995, 23% of the nation s soybean acreage was treated with a combination of four or more active ingredients while 28% received three active ingredients, 35% received two active ingredients and 12% was treated with just a single herbicide active ingredient [60]. In 1994, 43% of U.S. soybean acreage were cultivated during the growing season [52]. The average cultivated acre was cultivated one time during the season in Cultivations were targeted at weeds that escaped standard herbicide treatments. Transgenic Soybeans After being absorbed by plants, the herbicide glyphosate inhibits the enzyme 5- enolpyruvylshikimate-3-phosphate synthase (EPSPS). Glyphosate binds to EPSPS resulting in EPSPS s inhibition, causing the plant to starve for EPSP and the metabolic products derived from EPSP [53]. The ability to metabolize glyphosate is distributed widely among soil bacteria. Research demonstrated that EPSPS from a number of bacteria exhibited tolerance to glyphosate [53]. Monsanto scientists collected bacterial cultures from diverse sources and analyzed them for their tolerance to glyphosate. The EPSPS with the highest tolerance to glyphosate found in the screening was CP4 EPSPS from agrobacterium tumifacien, that demonstrated extremely high glyphosate tolerance [53]. The gene from CP4 EPSPS was cloned and introduced into soybeans by the particle acceleration method. Soybean cultivar A5403, a commercial variety developed by ASGROW Seed Company was used for the transformation [54]. The lead soybean line with a Roundup Ready gene is denoted , and expresses the 5

6 CP4 EPSPS gene product. Upon glyphosate treatment the transgenic plant remains unaffected because the continued action of the introduced glyphosate-tolerant EPSPS enzyme meets the plant s need for aromatic amino acids. The endogenous EPSP is inhibited by glyphosate (upon glyphosate treatment), however, the plant relies on the introduced glyphosate-tolerant EPSPS for EPSP synthesis [53]. Line has been used in various breeding programs to develop new cultivars with a Roundup Ready gene (Roundup Ready is Monsanto s trademark for its genes conferring glyphosate tolerance). Over 150 seed companies offer more than 1,000 Roundup-Ready varieties. The use of glyphosate over-the-top of Roundup Ready soybeans was researched extensively prior to and immediately after their introduction in Roundup Ready soybeans were evaluated under an EUP in 1995 in 14 states in the Midwest and Mid Atlantic. A single application of glyphosate at kg/ha provided annual weed control throughout the entire growing season [55]. In a 1997 experiment, all application timings of glyphosate (at weed heights of 7.5, 15, 23 and 36 cm) provided season-long control of giant foxtail, common lambsquarters and common cocklebur. The 7.5 cm timing was the only treatment to provide better than 90% control of smartweed. (All other glyphosate treatments provided 78-89% control.) All glyphosate applications provided yields equal to the weed-free comparison. All comparison treatments yielded significantly lower than weed-free comparison [56]. Research has shown in northern soybean states that a single postemergence application of Roundup controls all weeds commonly found in soybeans. [64] Figure 26.2 shows the increase in planting of Roundup Ready soybeans in the US since their introduction in The Roundup Ready technology was planted on two-thirds of the nations soybean acres in Table 26.4 shows adoption of Roundup Ready soybeans by state in

7 Table 26.3 shows estimates of U.S. soybean acreage treated with individual active ingredients for the years Glyphosate usage increased to 76% of acreage treated in 2001, from 20% in 1995 (used as a burndown or spot treatment), while most other active ingredients recorded declines in acreage treated. Postemergence glyphosate applications largely replaced the previous widespread use of the ALS-inhibiting herbicides (imazethapyr, imazaquin) and the herbicides that had been used in combination with them (pendimethalin, trifluralin). Recent research indicates that glyphosate alone provides superior weed control and soybean yields in comparison to these previously-used standard treatments (see Table 26.5). In addition to changing herbicide use patterns, US soybean growers have also changed tillage practices following the introduction of Roundup Ready soybeans. A recent survey by the American Soybean Association indicated that 53% of US soybean growers reported making fewer tillage passes through their fields since 1995 with the average reduction reported as 1.8 tillages/acre [63]. Improved weed control in the Roundup Ready system reduced the need to cultivate. Table 26.6 shows estimates of the costs and herbicide amounts used with the Roundup Ready soybean system by state. The average use rate of glyphosate is estimated at.95 lb AI/A. The system costs US soybean growers $475 million in herbicide costs and $300 million in technology fees. The total cost of the Roundup Ready technology is approximately $15.51 per acre. Alternative Herbicides Several new herbicide active ingredients and combination products were introduced to the US soybean market including Boundary, Authority, Flexstar, Raptor, Harmony GT and FirstRate [67], [68], [69]. Several of these products contain active ingredients that are ALS inhibitors (FirstRate, Harmony GT, Raptor) and as a result, cannot effectively control ALS-resistant weed populations. Generally these active ingredients have been shown to work best in combination with other products which 7

8 extend the period or spectrum of control. For example FirstRate needs to be combined with other products such as Dual or Python for effective control of lambsquarters and pigweed [69]. Boundary is being marketed as a preemergence component with a preplanned postemergence application [67]. Authority contains an active ingredient, sulfentrazone, that is particularly effective in controlling weed species that have developed populations resistant to ALS inhibitor herbicides. As a result, one of its primary uses is in a combination product, Canopy XL, with chlorimuron.[70] Experiments in Illinois demonstrated that a combination of Flexstar and Fusion provided 96-99% control of foxtail, pigweed, ragweed, and smartweed [66]. However, this combination only provides fair control of cocklebur, lambsquarters, and velvetleaf. University extension weed control guides rate as many as 190 herbicide treatments for soybeans that do not contain glyphosate [35]. One of the reasons that the Roundup Ready technology expanded so rapidly is due to the effectiveness of glyphosate on a broad spectrum of weed species. Table 26.7 displays effectiveness ratings for Roundup and 20 major product alternatives. 12 of the product alternatives contain a single active ingredient while 8 are combinations of two active ingredients. Table 26.8 lists the 20 alternatives with their active ingredient names, rates of application and costs. Roundup s effectiveness is rated at least good on 20 of the 22 weed species infesting soybeans (Table 26.7). For the other two species Roundup provides fair control. The highest number of good and excellent ratings for an alternative is 17 for Boundary, which is a combination of metribuzin and s-metolachlor. All other alternatives score between 4 and 13 good or excellent ratings. Although rated good-excellent on a large number of weeds, Boundary is applied preemergence and does not provide season-long control. As a result weed guides indicate that Boundary must be followed with a planned postemergence herbicide program (see above) [36], [40]. One of the reasons for rapid adoption of Roundup Ready soybeans is the excellent control it provides of common waterhemp which (as noted above) had grown resistant to many of 8

9 the conventional herbicides [65]. In 1996 experiments, imazaquin, imazethapyr and chlorimuron provided 15-25% control of common waterhemp while.75 lb. AI of glyphosate applied over glyphosate tolerant soybeans provided 98% control [57] [58]. Recent tests with newly-registered active ingredients indicate that combinations of 4-5 active ingredients could provide effective weed control of common grasses and broadleaves approximately equal to those provided by Roundup. Tables 26.9 and display recent research results for combinations of herbicide active ingredients in comparison to the use of glyphosate. Estimated impacts A survey of Extension Service weed scientists solicited herbicide replacement scenarios for Roundup. Responses were received from 23 of the major soybean producing states. These herbicide replacement scenarios are presented in Table Replacement scenarios have been assigned to the other 8 states based on a neighboring state. For most states, the specialists indicated that at least 3 products would have to be used to effectively replace Roundup. These combinations would be required in order to achieve good or excellent control (Table 26.7) of the most common weed species in the state (Table 26.2). Table displays estimates of the per-acre costs and use rates for the Roundup and alternative program by state. Most Roundup programs use approximately 1 lb AI and cost $15-16/A. Most alternative programs cost $30-40/A and utilize more than one pound of active ingredient per acre. Table simulates the replacement of the Roundup program with the alternative program by state. The estimates are presented in terms of the impacts of the Roundup program having been adopted instead of the alternative programs. US soybean growers are saving approximately $1.0 billion per year from using the Roundup program instead of the alternative programs. The Roundup program results in a reduction of 28.7 million pounds of herbicide active ingredients applied to soybeans. 9

10 The estimate of $1.0 billion in cost savings due to Roundup Ready soybeans is considerably higher than previous NCFAP estimates of $ million/year [76]. The earlier estimates measured reductions in herbicide expenditures by all soybean growers as a result of reduced prices for herbicides, which resulted from the introduction of the Roundup Ready technology. The aggregate total of $220 million/year implies a savings of $2.93/a on 75 million soybean acres in No estimates were made in the earlier reports of the reduced cost of tillage or of reduced cost of making fewer herbicide application trips across the field. USDA survey data for 2001 indicate that US soybean growers applied glyphosate an average of 1.3 times per acre [2]. As noted above, the average soybean acre was treated 1.7 times with herbicides in Assuming a reduction of.4 trips per acre at a cost per trip of $3/A [77] implies an aggregate reduction of herbicide application costs of $60 million/yr on 50 million acres planted with Roundup Ready soybeans. A reduction of 1.8 tillage trips has been recorded on approximately onehalf of US soybean acreage since the planting of Roundup Ready soybeans began (see above) assuming $6/A for a cultivation trip [78] implies an aggregate reduction in cultivation costs of $315 million. The impact estimates in this report represent a simulation of the costs that growers would incur if they replaced the Roundup Ready program with an equally effective herbicide program to control problem weeds without the need for additional cultivation. Most of the replacement scenarios specified by University weed scientists rely on newlyregistered herbicide active ingredients and combination products. It is not likely that soybean growers would simply return to the herbicide programs that they were using before the introduction of the Roundup Ready program. As noted above, significantly large resistant weed populations had developed for the most widely-used herbicidesimazethapyr and other ALS inhibitors. In addition, the previously-used herbicides did not control all the important weed species season-long and had to be supplemented with cultivation. Soybean farmers have become used to the benefits of the Roundup Ready system the use of one herbicide active ingredient to control all of the important weed species in one 10

11 or two applications without the need for supplemental cultivation. The scenarios specified in this analysis of alternative herbicides for glyphosate accomplish the same end resultcontrol of the important weed species in one or two applications without the need for supplemental cultivation ---but at a higher cost ($20/A on 50 million acres). No estimates are made of the impact on soybean production of the adoption of the Roundup Ready technology. Several states (NY, KS, SD) have recorded substantial increases in soybean acreage since the introduction of Roundup Ready soybeans (see Figure 26.3). One of the major reasons for the expanded acreage in these states is the widespread planting of Roundup Ready soybeans which provides growers in these states with an economical means of controlling particularly tough weed species [79]. An emerging concern with Roundup Ready soybean technology is the development of glyphosate resistant weed populations such as Marestail, which has been confirmed to be resistant in several states and may require additional management tactics. 11

12 Table 26.1 Soybean Acreage, Production and Value: 2000 State Area Harvested (000A) Yield (Bushels) Production (000Bushels) Price per Bushel ($) Value of Production (Million $) AL AR DE FL GA IL IN IA KS KY LA MD MI MN MS MO NE NJ NY NC ND OH OK PA SC SD TN TX VA WV WI Total Source: [41] [42] 12

13 Table 26.2: Most Common Weed Species: Soybeans AL AR DE FL GA IL IN IA KS KY LA MD MI MN MS Cocklebur X X X X X X X X X X X X X X Morningglory X X X X X X X X X X X X Pigweed X X X X X X X X X X X X X X Sicklepod X X X X X X Lambsquarters X X X X X X X X Ragweed X X X X X X X X FL Beggarweed X X Fl Pusley X X Velvetleaf X X X X X X X X Smartweed X X X X X Jimsonweed X X X X X Hemp sesbania X X X Prickly sida X X X X Crabgrass X X X X X X X X X X Foxtail X X X X X X X X X Panicum X X X X X X Goosegrass X X X Signalgrass X X X Barnyardgrass X X X Johnsongrass X X X X X X X X X Shattercane X X Nutsedge X X X X X X Source [3] [4] 13

14 Table 26.2: Most Common Weed Species: Soybeans (cont.) MO NE NJ NC ND OH OK PA SC SD TN TX VA WI Cocklebur X X X X X X X X X X X X Morningglory X X X X X X X X X X Pigweed X X X X X X X X X X X X X Sicklepod X X X Lambsquarters X X X X X X X X X X X X Ragweed X X X X X X X X FL Beggarweed X Fl Pusley Velvetleaf X X X X X X X X Smartweed X X X Jimsonweed X X Hemp sesbania X X Prickly sida X X X Crabgrass X X X X X X X Foxtail X X X X X X X X Panicum X X X X X X Goosegrass X X X Signalgrass X X X Barnyardgrass X Johnsongrass X X X X X X X X Shattercane X X X Nutsedge X X X Source: [3] [4] 14

15 Table 26.3 Herbicide Use, US Soybeans (% Acres Treated) ,4-D ,4-DB 1 <1 1 <1 <1 Acifluorfen Alachlor <1 Bentazon Chlorimuron Clethodim Clomazone <1 <1 Cloransulam Dimethenamid <1 <1 Ethalfluralin 1 1 <1 <1 <1 Fenoxaprop Fluazifop Flumetsulam <1 Flumiclorac 2 1 <1 <1 <1 <1 Fomesafen Glyphosate Imazamox Imazaquin Imazethapyr Lactofen Linuron <1 <1 <1 Metolachlor Metribuzin Paraquat <1 Pendimethalin Quizalofop <1 <1 S-Metolachlor <1 Sethoxydim Sulfentrazone Thifensulfuron Trifluralin Source: [2] 15

16 Table 26.4 Herbicide Tolerant Transgenic Soybean Adoption: 2001 State Area Harvested (000A) HT % HT Acres (000A) Source AL [5] AR [1] DE [6] FL [7] GA [8] IL [1] IN [1] IA [1] KS [1] KY [2] LA [2] MD [9] MI [1] MN [1] MS [1] MO [1] NE [1] NJ [10] NY [11] NC [2] ND [1] OH [1] OK [12] PA [13] SC [14] SD [1] TN [2] TX [15] VA [16] WV [17] WI [1] Total

17 Table 26.5 Iowa Herbicide Performance Evaluation: Soybeans (1) Imazethapyr Glyphosate Pendimethalin Weed Control (%) Foxtail Velvetleaf Waterhemp Lambsquarters Yield (bu/a) Source: [72] 17

18 Table 26.6 Herbicide Use and Cost, Transgenic Soybean Acreage State HT Acreage (000) Lbs. AI Technology Fee (000$) 1 Herbicide Cost 2 (000$) Total Cost Source 3 Per Acre (000/yr.) (000$) ($/A) AL [5] AR [2] DE [6] FL [7] GA [8] IL [2] IN [2] IA [2] KS [2] KY [2] LA [2] MD [9] MI [2] MN [2] MS [2] MO [2] NE [2] NJ [10] NY [11] NC [2] ND [2] OH [2] OK [12] PA [13] SC [14] SD [2] TN [2] TX [15] VA [16] WV [17] WI [2] Total 50, , , , ,776 $ Calculated at $6/A [75] 2 Calculated at $10/Lb AI [36] 3 Source of per acre rate 18

19 Table 26.7 Effectiveness Ratings: Soybean Herbicides Weed species Roundup Python Classic Reflex Dual II Magnum Canopy XL Boundary Flexstar Fusion Canopy Pursuit Authority Firstrate Storm Squadron Select Raptor Harmony GT Pursuit Plus Assure Synchrony Cocklebur E F-G E F N F-G G F N F-G E P E G F-G N E F F N E Morningglory F-G P P-F F-G N F-G F-G F-G N F F-G E G F-G P N F-G P F N F Pigweed E E E E G E E E N E E G P F E N E E E N E Sicklepod F-G F-G F-G P-F N F G P-F N F-G P P P F-G N P P N F-G Lambsquarters F-G G-E P P P-F G E F N G-E P G N P F-G N F E G N E Ragweed F-G P F E P G G E N G P-F F G-E F-G P-F N F N-P F-E N F FL Beggarweed G F G G F G G P N G-E P P-F F-G P P N N E FL Pusley P-F E G G G N G-E F P-F F E E N N F Velvetleaf F-G G P-F P N F G P-F N F F-G F P-F F-G P-F N F-G G G N G Smartweed F-G E F-G F P E E F N G-E F-G P G F-G F-G N F-G G G N G Jimsonweed E F-G E G N F-G F E N F-G G P E E F-G N G P F N E Hemp sesbania G N G E N F E E N E N P E N N N E Prickly sida F-G F-G P P P F-G G N N G-E P G P F F-G N F P G N P Crabgrass E N P N E P E N G F F-G N N F E F-G N G-E F-G N Foxtail E N P N E P-F E N E F F-G F N N G E G N E G N Panicum G-E N P N G-E P E N E F F P-F N N F-G E F-G N G-E E N Goosegrass E N N N E P E N G P P P-F N N F G P N G N Signalgrass E N N N F-G P E N G P-F F-G P-F N N F-G G-E F-G N G N Barnyardgrass E N N N G-E P E N E F F F N N G-E E F-G N E G- E N Johnsongrass G-E N P N N-P N-P P-F N G-E N-P P-G P N N N-F G-E P-G N G- E Shattercane G N P N P P P N E P G N N F E G N G E N Nutsedge P-F N P-F N F P F N N P P F N N P N P P F N N Source: [31]-[39] E: Excellent G: Good F: Fair P: Poor N: None 19 N

20 Table 26.8 Rates and Costs of Alternative Herbicides for Soybeans Trade name Common Name Rate (formulated product/a) Rate (Lb AI/A) Cost ($/A) Classic Chlorimuron 0.67 oz Reflex Fomesafen 1.5 pt Dual II Magnum S-Metolachlor 1.5 pt Canopy XL Sulfentrazone Chlorimuron 6 oz Boundary Metribuzin s-metolachlor 1.25 pt Flexstar Fomesafen 1 pt Fusion Fluazifop Fenoxaprop 10 oz Canopy Chlorimuron Metribuzin 4 oz Pursuit Imazethapyr 1.44oz Authority Sulfentrazone 4 oz FirstRate Cloransulam 0.3 oz Storm Acifluorfen Bentazon 1.5 pt Squadron Imazaquin Pendimethalin 3 pt Select Clethodim 8 oz Raptor Imazamox 5 oz Harmony GT Thifensulfuron 0.5 oz Pursuit Plus Imazethapyr Pendimethalin 2.5 pt Assure II Quizalofop 8 oz Synchrony Chlorimuron Thifensulfuron 0.5 oz Python Flumetsulam 1.0 oz Source: [31] [32] [37] [40] 20

21 Table 26.9 Minnesota Herbicide Performance Evaluations in Soybeans Treatments Flumetsulam Cloransulam Clethodim Lactofen Sulfentrazone Cloransulam Fluazifop Fenoxaprop S-Metolachlor Metribuzin Fomesafen Fenoxaprop Fluazifop Fomesafen Fluazifop Fenoxaprop Thifensulfuron Glyphosate Weed Control (%) Foxtails Lambsquarters Pigweed Wild Mustard Yield (bu/a) Source: [71] Table Iowa Herbicide Performance Evaluation: Soybeans (2) Cloransulam Fomesafen Clethodim Cloransulam Lactofen Clethodim Glyphosate Weed Control (%) Foxtail Velvetleaf Waterhemp Ragweed Lambsquarters Venice Mallow Cocklebur Source: [72] 21

22 Table Herbicide Alternatives for Roundup for Soybeans State Source AL Storm Squadron Select [30] AR Storm Squadron Select [30] DE Canopy Dual II Magnum Reflex [6] FL Canopy Dual II Magnum [7] GA Canopy Dual II Magnum [8] IL Boundary Flexstar Fusion [18] IN Dual II Magnum Pursuit Storm [19] IA Boundary Flexstar Select [73] KS Boundary FirstRate Select [20] KY Storm Squadron Select [21] LA Storm Squadron Select [30] MD Dual II Magnum Canopy XL Raptor [9] MI Canopy XL Harmony GT Pursuit Plus [22] MN Boundary Fusion Reflex [74] MS Storm Squadron Select [23] MO Flexstar Fusion Boundary [30] NE Pursuit Plus Authority [24] NJ Dual II Magnum Canopy XL [10] NY Dual II Magnum FirstRate Python [11] NC Classic Dual II Magnum Canopy [25] ND Authority Select Harmony GT [26] OH Dual II Magnum Pursuit Storm [30] OK Boundary Select [30] PA Dual II Magnum Canopy XL Assure [13] SC Classic FirstRate Assure [14] SD Authority FirstRate Select [27] TN Squadron Flexstar Select [28] TX Boundary Select [30] VA Reflex Synchrony FirstRate [16] WV Reflex Synchrony FirstRate [30] WI Authority Raptor Assure [29] - Survey respondents specified several alternative programs that would be equally effective. For the purpose of this analysis, a single program is selected above. 22

23 Table Cost and Use Rates: Roundup Ready and Alternative Programs 1 State Roundup Program Alternative Program $/A Lb AI/A $/A Lb AI/A AL AR DE FL GA IL IN IA KS KY LA MD MI MN MS MO NE NJ NY NC ND OH OK PA SC SD TN TX VA WV WI Roundup Ready costs and use rates from Table Alternative program costs and rates based on specified product alternatives in Table and product costs and rates in Table

24 Table Herbicide Tolerant Transgenic Soybean Impacts: 2001 Changes In State HT Acres Production Costs Herbicide Use (000) ($/A) (000$) (Lbs. AI/A) (Lbs.) AL AR DE FL GA IL IN IA KS KY LA MD MI MN MS MO NE NJ NY NC ND OH OK PA SC SD TN TX VA WV WI Total

25 Figure 26.1 US: Soybean Yields bu/a Source: [42] Figure 26.2 US: Roundup Ready Soybean Adoption % Acres Source: [1] [80] 25

26 Figure 26.3 Soybean Acres 1997= NY SD KS Source: [42] 26

27 References: 1. USDA, Prospective Plantings, National Agricultural Statistics Service, March USDA, Agricultural Chemical Usage Field Crops Summary, (separate volumes), National Agricultural Statistics Service. 3. Bridges, David C., ed., Crop Losses Due To Weeds In The United States 1992, Weed Science Society of America, Weed Survey Southern States, Proceedings Southern Weed Science Society, January Everest, John, Auburn University, personal communication. 6. Van Gessel, Mark, University of Delaware, personal communication. 7. Brecke, Barry, University of Florida, personal communication. 8. Prostko, Eric, University of Georgia, personal communication. 9. Ritter, Ron, University of Maryland, personal communication. 10. Majek, Brad, Rutgers University, personal communication. 11. Hahn, Russell, Cornell University, personal communication. 12. Murray, Don, Oklahoma State University, personal communication. 13. Curran, William, Pennsylvania State University, personal communication. 14. Murdock, Ed, Clemson University, personal communication. 15. Smith, Dudley, Texas A&M University, personal communication. 16. Hagood, Scott, Virginia Polytechnic University, personal communication. 17. Chandron, Rakesh, West Virginia State University, personal communication. 18. Sprague, Christy, University of Illinois, personal communication. 19. Bauman, Tom, Purdue University, personal communication. 27

28 20. Peterson, Dallas, Kansas State University, personal communication. 21. Green, J. D., University of Kentucky, personal communication. 22. Renner, Karen, Michigan State University, personal communication. 23. Byrd, John, Mississippi State University, personal communication. 24. Martin, Alex, University of Nebraska, personal communication. 25. York, Alan, North Carolina State University, personal communication. 26. Zollinger, Richard, North Dakota State University, personal communication. 27. Wrage, Leon, South Dakota State University, personal communication. 28. Hayes, Robert, University of Tennessee, personal communication. 29. Boerboom, Chris, University of Wisconsin, personal communication. 30. Assigned. 31. Pest Management Recommendations for Field Crops: 2000, UM/UD/PSU/Rutgers/VPI/WVU, Cooperative Extension Services, Bulletin Zollinger, Richard, 2002 North Dakota Weed Control Guide, North Dakota State University, January Georgia Pest Control Handbook, Cooperative Extension Service, University of Georgia Alabama Pest Management Handbook, Auburn University Cooperative Extension Service. 35. Kells, James J., et al, Weed Control Guide for Field Crops: 2001, MSU Extension, Bulletin E Gunsolus, J. L., et al, Cultural and Chemical Weed Control in Field Crops: 2002, UM Extension, BU S North Carolina Agricultural Chemicals Manual, College of Agriculture and Life Sciences, North Carolina State University. 38. Illinois Agricultural Pest Management Handbook: 2002, UI Extension. 28

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31 67. New Tools for the Tank, Soybean Digest, February 15, Soybean Herbicides Include New Chemistry, Soybean Digest, February 15, New Herbicide Bags Giant Ragweed, Soybean Digest, March 1, Hulting, Andrew G., et al, Soybean Varietal Response to Sulfentrazone, in 1999 Proceedings Illinois Crop Protection Technology Conference. 71. Gunsolus, Jeffrey L. and George Nelson, Herbicide Performance in Soybeans at Morris, MN-2001, 2001 Soybean Research Report, University of Minnesota, available at: Owen, Michael D. K., et al, Weed Science Research Program, Iowa State University, available at: Owen, Michael, Iowa State University, personal communication. 74. Gunsolus, Jeffrey, University of Minnesota, personal communication. 75. Carlson, Gerald A., Economics of Biotechnology, North Carolina State University, December Carpenter, Janet E. and Leonard P. Gianessi, Agricultural Biotechnology: Updated Benefit Estimates, National Center for Food and Agricultural Policy, January Brees, Melvin, Soybean Cost-Return Budget for Southwest Missouri, Department of Agricultural Economics, University of Missouri, FBM-1201, December Cultivation: An Effective Weed Management Tool, Iowa State University, University Extension, PM-1623, Revised June Kansas Increases Soybean Acreage, High Plains Journal, July 17, Marshall, Karen, Monsanto, personal communication. 81. Allen, S. M. and T.J. Hartberg, Weed Control in Soybeans with Applications of Imazethapyr Postemergence Following Pendimethalin Preplant Incorporated, in Proceedings North Central Weed Science Society, Congleton, W. Franklin, et al., Imazaquin (Scepter): A New Soybean Herbicide, Weed Technology, April

32 83. Peterson, Dallas E., The Impact of Herbicide Resistant Weeds on Kansas Agriculture, in Proceedings North Central Weed Science Society, Hager, Aaron G., et al., Identification of a Smooth Pigweed Biotype in Illinois Resistant to Various ALS-Inhibiting Herbicides, in Proceedings North Central Weed Science Society,