Progress 03/01/15 to 09/30/19
Outputs
Target Audience:Producers and agricultural professionals Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?There was 1 PhD student and 1 Postdoc that worked on several sub-objectives. Also 1 undergraduate student worked closely and was trained on the variosu aspects of weed management spray equipment. How have the results been disseminated to communities of interest?1. Demonstration Field Tours where farmers and Ag professionals had a chance to see how different herbicides worked on resistant weeds. 2. Power point presentations during extension meetings that we designed for producers and AG profesional. 3. There were also workshops on managing resistant weeds that were attended by producers (see impact section) 4. Articles writen for local newspapers, newsletters and trade journals 5. Total of 7 sceintific papers were also published What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Impacts and Benefits: Increase in herbicide resistant weeds requires planned evaluation of wide array of herbicides with different modes of actions. Based on herbicide screening we were able to determine the top five (best) herbicides for pre-emergence (PRE) and post-emergence (POST) control of glyphosate-resistant giant ragweed and HPPD-resistant waterhemp in soybeans and corn, which gave our farmers additional tools for managing resistance in these two weeds. Information from this research was also used to update Nebraska Weed Guide. For example the Guide was sold at 12,000 copies in 2016; 18,000 copies in 2017; and 12000 copies in 2018. Material was also used for developing material for 16 workshops about "Weed Resistance" held in 2015, 2016, 2017, 2018. There was a total of 320 farmers that attended, which manage about 340,000 acres of land. Based on several surveys of those who attended Field Tours and Workshops indicated that attendees will use our recommendations for management of these two species. Also, attendees indicated that the information provided was worth at $50-60 per acre in the form of savings on herbicide costs due to selection of the most appropriate herbicide. Therefore, the conservative estimate of overall financial impact might range from 9.6 million to 12 million (340,000 acres x $50 = 17 mil or 340,000 x $60 = 20 mil). Producers are realizing, slowly but for sure, that weed control must be diversified and that weed control based only on glyphosate alone is not sustainable. As a result, we are beginning to see a major change in action on the overall use of herbicides. There is an increase on the use of PRE and POST products with multiple modes of action, which will help in fighting resistant weeds. 2. STATEMENT OF PROBLEM AND JUSTIFICATION The wide spread use of Roundup Ready crops and repeated use of glyphosate herbicide resulted in glyphosate resistant weeds (USDA 2012). Currently, 13 weed species in the USA have evolved resistance to glyphosate and 24 species worldwide (Heap 2012). Glyphosate-resistant marestail [Conyza canadensis (L.) Cronquist], kochia [Kochia scoparia (L.) Roth], common waterhemp (Amaranthus rudis) and giant ragweed (Ambrosia trifida L.) have been confirmed in Nebraska and their management is of major concern for corn and soybean producers. Therefore, over a 5year period (2014-2019) we studied various aspects of integrated control of Glyphosate resistant giant ragweed and HPPD resistant waterhemp in Nebraska. 4. OBJECTIVES Outputs by objective: Sub-objective 1.1: Confirmation of glyphosate-resistant (GR) giant ragweed in Nebraska Field experiments were conducted in David City, NE at a site with suspected GR giant ragweed population. The estimated level of glyphosate resistance for 4", 8", and 12" tall giant ragweed 21 DAT was 14X, 36X, and 60X, respectively. Sub-objective 1.2. Control of Giant Ragweed with flaming. Flaming was conducted, however results indicated that flaming caused just a temporary injury of giant ragweed, thus should not be recommended as a viable tool for giant ragweed control. Sub-objective 1.3: Control of Glyphosate resistant Giant Ragweed with various herbicides in corn Total of 12 herbicides for pre-emergence (PRE) control in corn were tested. The best PRE control (>90%) of giant ragweed was achieved with the following five treatments (and their rates/acre): Atrazine (2qt/a), Balance Flexx (6oz/a), Corvus (5.6oz), Guardsman Max (4pts) and Lumax EZ (2.7qrt). Sub-objective 1.4: Control of Glyphosate resistant Giant Ragweed with various herbicides in soybean Total of 10 herbicides for pre-emergence (PRE) control in soybean were tested. The best PRE control (>90%) of giant ragweed was achieved with the following five treatments (and their rates/acre): OpTill (20 oz/a), Authority First (6.4oz/a), First Rate (0.6oz), Pursuit +Warrant (4oz+2pts) and Valor (3oz). Objective II: Integrated management of HPPD-resistant Common Waterhemp Sub-Objectives: 2.1. Field studies to confirm HPPD-resistant in common waterhemp in Nebraska. This study confirmed the first case of the HPPD-common waterhemp in Nebraska, and the third in the United States. The resistance level was the highest to mesotrione (18 x), followed by tembotrione (5x), and topramezone (2x), most likely due to longer history of mesotrione use at the study site in a continuous seed corn production system. 2.2. Pollen mediated gene flow from HPPD-resistant common waterhemp to susceptible palmer amaranth under field conditions. More than 104,000 F1 (Palmer vs waterhemp cross) seedlings were screening with 175 g ai-1 mesotrione, which was used as a cutoff for eliminating false hybrids. It was expected that all F1 seedlings would have resistance to mesotrione. Power analysis detected high precision (>0.95) to detected intraspecific gene flow, which is below the theoretically expected value of near 1 (100% gene flow). This result is significant as Palmer amaranth and common waterhemp produce large amounts of seeds, are obligate outcrosser, and NTSR can confer resistance to different herbicide SOA. Therefore, even at low frequencies, PMGF can have important evolutionary consequences in weedy Amaranthus. Sub-objective 2.3. Control of HPPD resistant waterhemp with herbicides in corn. Total of 14 herbicides for PRE control in corn were tested. The best PRE control (>90%) of waterhemp was achieved with the following five treatments (and their rates/acre): (1) Fierce+Lumax (3oz+2.7qt/a); (2) Valor+Lumax (1.4oz+2.7qt); (3) Tricor+Lumax (4oz+2.7qt); (4) Verdict (16fl oz/a); and (5) Lumax+Harness (2.7qt+0.86pt/a) Also, PRE tankmixes of Lumax (2.7qt/A)+Harness (1.5 pt/A); Corvus (5.6oz)+atrazine (1.6qrts), and Zidua (2.5 oz/A)+Sharpen (3oz/A)+Atrazine (1pt) provided excellent PRE control, > 90% for 41 DAT. Sub-objective 2.4. Control of HPPD resistant waterhemp with herbicides in soybean Total of 13 herbicides for PRE control in soybean were tested. The best PRE control (>90%) of waterhemp was achieved with the following five treatments (and their rates/acre): (1) Boundary (2pt/a); (2) Authority First (5.0 oz); (3) Fierce (3oz); (4) Authority First + Prefix (5oz + 2pt); and (5) Zidua+ Sharpen (1.6oz + 1oz) . Sub-objective 2.5. Physiology and molecular biology of HPPD-resistant common waterhemp There was no difference in control of HPPD-R when mesotrione was applied with or without 2,000 g ai ha-1 malathion. In contrast, malathion, amitrole, and PBO fb tembotrione and topramezone enhanced HPPD-R control and biomass reduction. The HPPD-S was sensitive to all treatments applied; all treatment combinations controlled and reduced biomass of HPPD-S ≥ 96% and ≥84%, respectively. A similar trend was observed under field conditions. In addition, the LC-MS/MS analysis of the metabolism of mesotrione and tembotrione is consistent with the herbicidal activity of these herbicides on HPPD-S and HPPD-R in greenhouse and field studies. This study confirms the enhanced metabolism-based mesotrione, tembotrione, and topramezone resistance via P450 enzymes in HPPD-R. It was demonstrated that multiple P450 enzymes are causing resistance in HPPD-R. It remains unidentified whether another NTSR mechanism has arisen in this population. Postemergence application of P450 inhibitors, including malathion, amitrole, and PBO with HPPD-inhibitor herbicides (mesotrione, tembotrione, and topramezone) showed a potential for reversing HPPD-R to a susceptible phenotype. However, fully elucidated weed management strategies will require additional investigation on candidate P450 alleles causing this striking resistance.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2019
Citation:
Oliveira MC, Jhala AJ, Gaines T, Irmak S, Amundsen K, Scott JE, Knezevic SZ (2017) Confirmation
and control of HPPD-inhibiting herbicide-resistant waterhemp (Amaranthus tuberculatus) in
Nebraska. Weed Technology 31:67-79.
Oliveira MC, Gaines TA, Dayan FE, Patterson EL, Jhala AJ, Knezevic SZ (2017) Reversing resistance
to tembotrione in an Amaranthus tuberculatus (syn. Rudis) population from Nebraska, USA with
cytochrome P450 inhibitors. Pest Management Science 74: 2296-2305
Osipitan, O.A., Scott, J.E., Knezevic, S.Z. (2018). Tolpyralate Applied Alone and with Atrazine for
Weed Control in Corn . Journal of Agricultural Science, 10: 32-39.
Oliveira MC, Gaines TA, Dayan FE, Patterson EL, Jhala AJ, Knezevic SZ (2018) Intraspecific
Transference of Metabolism-Based Mesotrione Resistance in Dioecious Weedy Amaranthus. The Plant Journal 6:18-20.
Oliveira MC, Feist D. Eskelsen. Scott J, and S.Knezevic (2017) Weed Control in Soybean with
preemergence, and postemergence applied herbicides. Crop Management Journal, online.
Oliviera M, Gaines T, Jahala A, and S. Knezevic (2018). Inheritance of Mesotrione Resistance in
Amaranthus tuberculatus populat. from Nebraska. Frontier in Plant Science. Vol 9: Article 60.
Knezevic, S.Z., Osipitan, O.A., Scott, J.E. (2018). Alternative Herbicides for Control of
Glyphosate-Resistant Giant Ragweed in Nebraska . Sustainable Agricultural Research, 8:1
|
Progress 10/01/17 to 09/30/18
Outputs
Target Audience:Producers and Ag Professionals of Nebraska Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?One PhD student was trained for 4 years during this project. In 2018 we had several Field Tours that was attended by local producers and ag professionals How have the results been disseminated to communities of interest? 1. Field Tours provided visuals of the herbicide efficacy and opportunity to provide one-on-one teaching of local producers. 2. 2018 Nebraska Weed Guide: Herbicide efficacy data was used from this study for updating 2018 Weed Guide, which was printed at 12000 copies in 2018 year and distributed accross Nebraska. 3. Articles were also written for the Crop Protection Clinics and Power Point Presentations developed and presented during Crop Protection Clinics and Weed Resistance Workshops What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Impacts: Increase in herbicide resistant weeds requires planned evaluation of wide array of herbicides with different modes of actions. This was our first year of herbicide screening in soybeans and we were able to determine the top five (best) herbicides for pre-emergence (PRE) and post-emergence (POST) control of glyphosate-resistant giant ragweed and HPPD-resistant waterhemp in soybeans, which gave our farmers additional tools for managing resistance in these two weeds. Information from this research was also used to update Nebraska Weed Guide (sold at 12000 copies in 2018) and for developing material for 16 workshops about "Weed Resistance" held in 2015, 2016, 2017. 2018. There was a total of 320 farmers that attended, which manage about 340,000 acres of land. Based on several surveys of those who attended Field Tours and Workshops indicated that attendees will use our recommendations for management of these two species. Also, attendees indicated that the information provided was worth at $50-60 per acre in the form of savings on herbicide costs due to selection of the most appropriate herbicide. Therefore, the conservative estimate of overall financial impact might range from 9.6 million to 12 million (340,000 acres x $50 = 17 mil or 340,000 x $60 = 20 mil) Producers are realizing, slowly but for sure, that weed control must be diversified and that weed control based only on glyphosate alone is not sustainable. As a result, we are beginning to see a major change in action on the overall use of herbicides. There is an increase on the use of PRE and POST products with multiple modes of action, which will help in fighting resistant weeds. STATEMENT OF PROBLEM AND JUSTIFICATION The use of Roundup Ready crops and repeated use of glyphosate herbicide over last 20 years resulted in glyphosate resistant weeds (USDA 2012). Currently, 17 weed species in the USA have evolved resistance to glyphosate and 36 species worldwide (Heap 2012). Glyphosate-resistant marestail [Conyza canadensis (L.) Cronquist], kochia [Kochia scoparia (L.) Roth], common waterhemp (Amaranthus rudis) and giant ragweed (Ambrosia trifida L.) have been confirmed in Nebraska and their management is of major concern for corn and soybean producers. Therefore, it is suggested for the 5 years (2014-2019) to study various aspects of integrated control of resistant weeds in Nebraska. Specific objectives: The specific objectives of my program for this five year period will be to research various aspects of integrated control of resistant weeds in Nebraska to develop a frame work for optimizing herbicide use from a biological perspective. The areas of research include: Objective I: Integrated management of Glyphosate-resistant Giant ragweed. Giant ragweed is an early emerging summer annual commonly found throughout the row crop production system in the Midwest and eastern Corn Belt. Although giant ragweed has been around for many years, it has become a major weed in the last two decades, while in Nebraska for the last 6-7 years. Therefore, the overall goal of this study is to evaluate several control methods for GR giant ragweed and to use such data for developing a public awareness program. The specific sub-objectives are: Sub-objective 1.4: Control of Glyphosate resistant Giant Ragweed with various herbicides in soybean This year (2018) we evaluated series of various soybean herbicides in two studies. In the first study, a total of 10 herbicides for pre-emergence (PRE) control in soybean were tested. The best PRE control (>90%) of giant ragweed was achieved with the following five treatments (and their rates/acre): OpTill (20 oz/a), Authority First (6.4oz/a), First Rate (0.6oz), Pursuit +Warrant (4oz+2pts) and Valor (3oz). In the second study, 6 herbicides for post-emergence (POST) control of ragweed in soybean were tested. The best POST control (>90%) of giant ragweed was achieved with the following 4 treatments (and their rates/acre): (1) First rate (0.3 fl oz/a); (2) Phoenix (12.5 oz); (3) Flextar-GT (6oz/a); and (4) Rapor + UltraBlazer (4 oz + 16oz). Objective II: Integrated management of HPPD-resistant Common Waterhemp Introduction: The evolution of herbicide-resistant weeds and their management is a greatest challenge for weed scientists, crop consultants, and crop producers. Globally, more than 390 herbicide-resistant biotypes have been confirmed among more than 200 weed species (Heap 2013). In northeastern Nebraska, the first case of HPPD-inhibiting herbicide-resistant common waterhemp has been confirmed in 2013 in a seed production corn field by town of Tarnov. Currently (2018), HPPD resistance is becoming common seen throughout Nebraska. Sub-objective 2.4. Control of HPPD resistant waterhemp with herbicides in soybean Local farm (by Tarnov, NE) was infested with HPPD-resistant waterhemp and was utilized for conducting two studies soybeans. In the first study, 13 herbicides for PRE control in soybean were tested. The best PRE control (>90%) of waterhemp was achieved with the following five treatments (and their rates/acre): (1) Boundary (2pt/a); (2) Authority First (5.0 oz); (3) Fierce (3oz); (4) Authority First + Prefix (5oz + 2pt); and (5) Zidua+ Sharpen (1.6oz + 1oz) . In the second study, 15 herbicides for PRE+POST in soybean were tested. The best PRE control (>90%) of waterhemp was achieved with the following 5 treatments (and their rates/acre): (1) Boundary (2pt); (2) Prefix (2pt); (3) Zidua+Boundary (1.7oz/a + 2pt/a); (4) Boundary followed by Flexstart (2pt+1.75qt/a) and (5) Authority First followed by Flexstar GT (5oz+1.75qt/a). The above presented results include the list of best herbicide selection for control of both glyphosate-resistant giant ragweed and HPPD-resistant waterhemp were incorporated into Nebraska Weed Guide, "a go to book" by many farmers and pesticide industry members (printed at 12000 copies in 2018).
Publications
- Type:
Other
Status:
Published
Year Published:
2018
Citation:
2018 Guide for Weed, Disease and Insect Management in Nebraska
|
Progress 10/01/16 to 09/30/17
Outputs
Target Audience:Nebraska's Ag producers and Ag Industry Professionals involved in weed control Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?This project was used to train one PhD student and for two Field Tours (one for each weed) that was attended by local producers and ag professionals How have the results been disseminated to communities of interest?1. Field Tours provided visuals of the herbicide efficacy and opportunity to provide one-on-one teaching of local producers. 2. Nebraska Weed Guide: Herbicide efficacy data was used for updating Weed Guide, which was printed at 18000 copies in 2017 year and distributed accross Nebraska. 3. Articles were also written for the Crop Protection Clinics and Power Point Presentations developed and presented during Crop Protection Clinics and Weed Resistance Workshops What do you plan to do during the next reporting period to accomplish the goals?Following sub-objectives will be conducted during 2018 season I) Integrated control of glyphosate resistant giant ragweed: d. PRE in soybean f. POST in soybean (II) Integrated control of HPPD resistant waterhemp: d. PRE in soybean f. POST in soybean
Impacts
What was accomplished under these goals?
Impacts: Increase in herbicide resistant weeds requires careful evaluation of selective herbicides. In brief, with our second year of herbicide evaluations we were able to determine the top five (best) herbicides for pre-emergence and post-emergence control of glyphosate-resistant giant ragweed and HPPD-resistant waterhemp in corn, which gave our farmers additional tools for managing resistance in these two weeds. Information from this research was also used for updating Nebraska Weed Guide (sold at 18000 copies in 2017) and for developing material for 12 workshops about "Weed Resistance" held in 2015, 2016 and 2017. There was a total of 263 farmers that attended, which manage about 240,000 acres of land. Based on several surveys of those who attended Field Tour and Workshops indicated that attendees will use our recommendations for management of these two species. Also attendees indicated that the information provided was worth at $40-$50 per acre in the form of savings on herbicide costs due to selection of the most appropriate herbicide. Therefore, the conservative estimate of overall financial impact might range from 9.6 million to 12 million (240,000 acres x $40 = 9.6 mil or 240,000 x $50 = 12 mil) 1. PROJECT TITLE: Integrated Management of Herbicide Resistant Weeds in Nebraska 2. PRINCIPAL INVESTIGATOR: Dr. Stevan Knezevic, IWM Specialist, NEREC, 0.5 FTE Research and 0.5 FTE Extension 3. STATEMENT OF PROBLEM AND JUSTIFICATION The wide spread use of Roundup Ready crops and repeated use of glyphosate herbicide resulted in glyphosate resistant weeds (USDA 2012). Currently, 16 weed species in the USA have evolved resistance to glyphosate and 24 species worldwide (Heap 2012). Glyphosate-resistant marestail [Conyza canadensis (L.) Cronquist], kochia [Kochia scoparia (L.) Roth], common waterhemp (Amaranthus rudis) and giant ragweed (Ambrosia trifida L.) have been confirmed in Nebraska and their management is of major concern for corn and soybean producers. Therefore, it is suggested for the 5years (2014-2019) to study various aspects of integrated control of resistant weeds in Nebraska. 4. OBJECTIVES Specific objectives: The specific objectives of my program for this five year period will be to research various aspects of integrated control of resistant weeds in Nebraska to develop a frame work for optimizing herbicide use from a biological perspective. The areas of research include: Objective I: Integrated management of Glyphosate-resistant Giant ragweed. Giant ragweed is an early emerging summer annual commonly found throughout the row crop production system in the Midwest and eastern Corn Belt. Although giant ragweed has been around for many years, it has become a major weed in the last two decades, while in Nebraska for the last 5-6 years. Therefore the overall goal of this study is to evaluate several control methods for GR giant ragweed and to use such data for developing a public awareness program. The specific sub-objectives are: Sub-objective 1.3: Control of Glyphosate resistant Giant Ragweed with various herbicides in corn This was the second year (2017) that we conducted the tests of various corn herbicides in two studies. In the first study, a total of 12 herbicides for pre-emergence (PRE) control in corn were tested. The best PRE control (>90%) of giant ragweed was achieved with the following five treatments (and their rates/acre): Atrazine (2qt/a), Balance Flexx (6oz/a), Corvus (5.6oz), Guardsman Max (4pts) and Lumax EZ (2.7qrt). In the second study, 12 herbicides for post-emergence (POST) control of ragweed in corn were tested. The best POST control (>90%) of ragweed was achieved with the following 5 treatments (and their rates/acre): (1) 2,4D (16 fl oz/a); (2) Hornet (5loz); (3) Distinct (6oz/a); (4) Status (5 oz) and (5) Hornet+2,4D (4oz+8floz/a). Objective II: Integrated management of HPPD-resistant Common Waterhemp Introduction: The evolution of herbicide-resistant weeds and their management is a greatest challenge for weed scientists, crop consultants, and crop producers. Globally, more than 390 herbicide-resistant biotypes have been confirmed among more than 200 weed species (Heap 2013). Recently, studies reported evidence of HPPD-inhibiting herbicide resistant Palmer amaranth biotype in Kansas. In northeastern Nebraska, HPPD-inhibiting herbicide-resistant common waterhemp has been confirmed in a seed production corn field and multiple herbicide-resistant common waterhemp in Illinois (Hausman et al. 2011). Sub-objective 2.3. Control of HPPD resistant waterhemp with herbicides in corn. A farmers field (by Tarnov, NE) infested with HPPD-resistant waterhemp was utilized for conducting three studies. In the first study, 14 herbicides for PRE control in corn were tested. The best PRE control (>90%) of waterhemp was achieved with the following five treatments (and their rates/acre): (1) Fierce+Lumax (3oz+2.7qt/a); (2) Valor+Lumax (1.4oz+2.7qt); (3) Tricor+Lumax (4oz+2.7qt); (4) Verdict (16fl oz/a); and (5) Lumax+Harness (2.7qt+0.86pt/a) In the second study, 16 herbicides for post-emergence (POST) control in corn were tested. The best POST control (>90%) of waterhemp was achieved with the following 5 treatments (and their rates/acre): (1) Touchdown (36 fl oz/a); (2) Callisto-Xtra (20floz); (3) Callisto-Xtra+Liberty (20fl oz/a+29fl oz/a); (4) CallistoXtra + Bromoxynil (20fl/oz+1.5pt/a) and (5) Tricor + CallistoXtra (4oz+20floz/a). In the third study, 10 herbicides for PRE followed by POST control in corn were tested. The best PRE+POST control (>90%) of waterhemp was achieved with the following 5 treatments (and their rates/acre): (1) Lumax (2.7qt) + Aatrex (1.9pt/a) followed by Status (5oz); (2) Lumax (2.7qt) + Aatrex (1.9pt/a) followed by CallistoXtra (16fl oz/a); (3) Lumax (2.7qt) + Zidua (1.68pt/a) followed by Callsto Xtra (16 fl ox/a); (4) Lexar (1.7qt/a) followed by Status (5oz); and (5) Lumax (2.7qt) + Aatrex (1.9pt/a) followed by Touchdown (32fl oz); The above presented results on the best herbicide selection for control of both glyphosate-resistant giant ragweed and HPPD-resistant waterhemp were incorporated into Nebraska Weed Guide, "a go to book" by many farmers and pesticide industry members (printed at 18000 copies in 2017).
Publications
|
Progress 10/01/15 to 09/30/16
Outputs
Target Audience:Crop producers and other agricultural businesses Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Waterhemp Project was used for a Field Tour (whichwas attended by 58 localfarmers and 12 industry professionals) and for training of my PhD student (Maxwel Oliveira) How have the results been disseminated to communities of interest?Yes it was: 1. Field Tour in July 2. Data was presented at the yearlyCrop Protection Meetings on 6 locations across NEbraska 3. Data was also used to update Nebraska Weed Guide 4. Manuscript submitted to Weed Technology journal (in review) What do you plan to do during the next reporting period to accomplish the goals?To continue same objectives in soybean (eg. testing alternative PRE and POST herbicides) for giant ragweed and waterhemp control.
Impacts
What was accomplished under these goals?
Impacts: In general, my program helped optimize weed control and provided to crop producers and other agricultural businesses the most advanced knowledge on how to adjust their cropping practices related to weed resistance in giant ragweed and waterhemp as were able to determine alternative herbicides. Information from this research was also used for updating Nebraska Weed Guide (sold at 12000 copies in 2016) and for developing material for 8 workshops about "Weed Resistance" held in 2015 and 2016. There was a total of 188 farmers that attended, and they manage about 180,000 acres of land. Based on several surveys of those who attended Field Tour and Workshops indicated that the information provided was worth at $35-$50 per acre in the form of savings on herbicide costs due to selection of the most of appropriate herbicide. Therefore, the conservative estimate of overall financial impact might range from 6.3 million to 9 million (180000acres x $35 = 6.3mil or 180000 x $50 = 9mil) 1. PROJECT TITLE: Integrated Management of Herbicide Resistant Weeds in Nebraska 2. PRINCIPAL INVESTIGATOR: Dr. Stevan Knezevic, IWM Specialist, NEREC, 0.5 FTE Research and 0.5 FTE Extension 3. STATEMENT OF PROBLEM AND JUSTIFICATION The wide spread use of Roundup Ready crops and repeated use of glyphosate herbicide resulted in glyphosate resistant weeds (USDA 2012). Currently, 13 weed species in the USA have evolved resistance to glyphosate and 24 species worldwide (Heap 2012). Glyphosate-resistant marestail [Conyza canadensis (L.) Cronquist], kochia [Kochia scoparia (L.) Roth], common waterhemp (Amaranthus rudis) and giant ragweed (Ambrosia trifida L.) have been confirmed in Nebraska and their management is of major concern for corn and soybean producers. Therefore, it is suggested for the 5years (2014-2019) to study various aspects of integrated control of resistant weeds in Nebraska. 4. OBJECTIVES Overall objective: The overall objective of this research is to develop a multidisciplinary program for weed control that builds bridges among disciplines, especially between weed/crop ecology and herbicide technology. My program advocates the use of a combination of weed control methods ("the use of many little hammers"). It includes studies of weed ecology, crop-weed interactions as affected by cropping practices and nutrient management, herbicide technology and systems simulation. Specific objectives: The specific objective of my program for this five year period will be to research various aspects of integrated control of resistant weeds in Nebraska to develop a frame work for optimizing herbicide use from a biological perspective. The areas of research include: Integrated control of glyphosate resistant giant ragweed: 1.3: Control of Glyphosate resistant Giant Ragweed with various herbicides in corn Integrated control of HPPD resistant waterhemp: Sub-objective 2.3. Control of HPPD resistant waterhemp with herbicides in corn. Objective I: Integrated management of Glyphosate-resistant Giant ragweed. Giant ragweed is an early emerging summer annual commonly found throughout the row crop production system in the Midwest and eastern Corn Belt. Although giant ragweed has been around for many years, it has become a major weed in the last two decades, while in Nebraska for the last 5-6 years. Therefore the overall goal of this study is to evaluate several control methods for GR giant ragweed and to use such data for developing a public awareness program. The specific sub-objectives are: Sub-objective 1.3: Control of Glyphosate resistant Giant Ragweed with various herbicides in corn As part of this objective several studies for testing herbicides for pre-emergence (PRE) and post-emergence (POST) control in corn and soybean. More specific details on herbicides are listed below (Table 1-Table 3). Table 1. Giant Ragweed Control in Corn with Selected PRE and POST Treatments - EPP TREATMENTS HERBICIDE RATES APPLICATION TIME 1.Atrazine 2 qt/a PRE 2.Balance Flexx 6 oz/a PRE 3.Balance Flexx; Atrazine 6 oz/a; 1 qt/a PRE 4.Callisto 6 oz/a PRE 5.Corvus 5.6 oz/a PRE 6.Fierce 3 oz/a PRE 7.Guardsman Max 4 pt/a PRE 8.Lumax EZ 2.7 qt/a PRE 9.Sharpen 3 oz/a PRE 10.Valor; Atrazine 2 oz/a; 1 qt/a PRE 11.Verdict 16 oz/a PRE 12.Zemax 2 qt/a PRE Table 2. Giant Ragweed Control in Corn with Selected PRE and POST Treatments TREATMENTS HERBICIDE RATES APPLICATION TIME 1.Nontreated Check 2.Atrazine; 2,4-D 2 qt/a; 16 oz/a PRE; POST 3.Balance Flexx; 2,4-D 6 oz/a; 16oz/a PRE; POST 4.Balance Flexx; Atrazine; 2,4-D 6 oz/a; 1 qt/a; 16 oz/a PRE; PRE; POST 5.Callisto; Hornet 6 oz; 5 oz/a PRE; POST 6.Corvus; 2,4-D 5.6 oz/a; 16 oz/a PRE; POST 7. 2,4-D 16 oz/a POST 8.Guardsman Max; 2,4-D 4 pt/a; 16 oz/a PRE; POST 9.Lumax EZ; 2,4-D 2.7 qt/a; 16 oz/a PRE; POST 10.Sharpen; Distinct 3 oz/a; 6 oz/a PRE; POST 11.Verdict; Status 16 oz/a; 5 oz/a PRE; POST 12.Zemax; Status 2 qt/a; 5 oz/a PRE; POST Table 3. Selected POST Treatments for Control of Glyphosate Resistant Giant Ragweed in Corn TREATMENTS HERBICIDE RATES APPLICATION TIME 1.2,4-D 16 oz/a POST 2.Beacon 0.76 oz/a POST 3.Distinct 6 oz/a POST 4.Hornet 5 oz/a POST 5.Laudis; Atrazine 3 oz/a; 0.5 qt/a POST 6.Status 5 oz/a POST Objective II: Integrated management of HPPD-resistant Common Waterhemp Introduction: The evolution of herbicide-resistant weeds and their management is a greatest challenge for weed scientists, crop consultants, and crop producers. Globally, more than 390 herbicide-resistant biotypes have been confirmed among more than 200 weed species (Heap 2013). Recently, studies reported evidence of HPPD-inhibiting herbicide resistant Palmer amaranth biotype in Kansas. In northeastern Nebraska, HPPD-inhibiting herbicide-resistant common waterhemp has been confirmed in a seed production corn field and multiple herbicide-resistant common waterhemp in Illinois (Hausman et al. 2011). Common Waterhemp: Several research projects have been accomplished to study biology and control of common waterhemp Sub-Objectives: Sub-objective 2.3. Control of HPPD resistant waterhemp with herbicides in corn. As part of this objective the farmers field (by Tarnov, NE) was utilized to do several studies for testing a whole series of over 30 herbicides for pre-emergence (PRE) and post-emergence (POST) control in corn (tables 4 and 5 are only presented due to limited space) as part of Experiment 3 (see original proposal from 2015) Table 4. Preemergent Callisto dose response effects Trt No Treatment Name Rate Rate Unit Growth Stage 1 Nontreated 2 Lumax 1.25 qt/a PRE 3 Lumax 2.5 qt/a PRE 4 Lumax 5 qt/a PRE 5 Lumax 10 qt/a PRE 6 Callisto 2.7 oz/a PRE 7 Callisto 5.4 oz/a PRE 8 Callisto 10.8 oz/a PRE 9 Callisto 21.6 oz/a PRE 10 Dual II Magnum 1.75 pt/a PRE atrazine 0.63 qt/a PRE Callisto 2.7 oz/a PRE 11 Dual II Magnum 1.75 pt/a PRE atrazine 0.63 qt/a PRE Callisto 5.4 oz/a PRE 12 Dual II Magnum 1.75 pt/a PRE atrazine 0.63 qt/a PRE Callisto 10.8 oz/a PRE 13 Dual II Magnum 1.75 pt/a PRE atrazine 0.63 qt/a PRE Callisto 21.6 oz/a PRE 14 Dual II Magnum 1.75 pt/a PRE atrazine 0.63 qt/a PRE Table5. Control of HPPD resistant waterhemp - Preemergence residual efficacy Trt No. Treatment Name Rate Rate Unit Other Rate Other Rate Unit Growth Stage 1 Lumaz EZ 2.7 qt/a 2780 g ai/ha PRE Harness 1.5 pt/a 1470 g ai/ha PRE 2 Corvus 5.6 oz/a 129 g ai/ha PRE Atrazine 1.6 qt/a 1800 g ai/ha PRE 3 Zidua 2.5 oz/a 149 g ai/ha PRE Sharpen 3 oz/a 75 g ai/ha PRE Atrazine 1 pt/a 560 g ai/ha PRE 4 Verdict 15 oz/a 730 g ai/ha PRE Outlook 5 oz/a 263 g ai/ha PRE 5 Zidua 1.51 oz/a 90 g ai/ha PRE 6 Zidua 3.02 oz/a 180 g ai/ha PRE 7 Zidua 4.53 oz/a 270 g ai/ha PRE 8 Surestart 2.5 pt/a 1490 g ai/ha PRE 9 Anthem ATZ 32 oz/a 1260 g ai/ha PRE
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Progress 03/01/15 to 09/30/15
Outputs
Target Audience:
Nothing Reported
Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Training of a PhD student How have the results been disseminated to communities of interest?Yes. 1. There were two Field Days, one at each location. whichprovided opportunity for farmersto see first hand what the resistance in these weeds look like, there wasover 300 farmers attending. What do you plan to do during the next reporting period to accomplish the goals?During 2016 season we wil do objectives: (I) Integrated control of glyphosate resistant giant ragweed: b. EPP in corn c. PRE in corn d. PRE in soybean (II) Integrated control of HPPD resistant waterhemp: b. EPP in corn c. PRE in corn d. PRE in soybean
Impacts
What was accomplished under these goals?
Introduction: The wide spread use of Roundup Ready crops and repeated use of glyphosate herbicide resulted in glyphosate resistant weeds (USDA 2012). Currently, 13 weed species in the USA have evolved resistance to glyphosate and 24 species worldwide (Heap 2012). Glyphosate-resistant marestail [Conyza canadensis (L.) Cronquist], kochia [Kochia scoparia (L.) Roth], common waterhemp (Amaranthus rudis) and giant ragweed (Ambrosia trifida L.) have been confirmed in Nebraska and their management is of major concern for corn and soybean producers.Therefore, it is suggested for the 5years (2014-2019) to study various aspects of integrated control of resistant weeds in Nebraska. Overall objective: The overall objective of this research is to develop a multidisciplinary program for weedcontrol that builds bridges among disciplines, especially between weed/crop ecology and herbicidetechnology. My program advocates the use of a combination of weed control methods ("the use of manylittle hammers"). It includes studies of weed ecology, crop-weed interactions as affected by cropping practices and nutrient management, herbicide technology and systems simulation. Specific objectives: The specific objective of my program for this five year period will be to research variousaspects of integrated control of resistant weeds in Nebraska to develop a frame work for optimizing herbicideuse from a biological perspective. The areas of research include: (I) Integrated control of glyphosate resistant giant ragweed: a. Glyphosate dose response b. EPP in corn c. PRE in corn d. PRE in soybean e. POST in corn f. POST in soybean g. Flaming giant ragweed (II) Integrated control of HPPD resistant waterhemp: a. Glyphosate dose response b. EPP in corn c. PRE in corn d. PRE in soybean e. POST in corn f. POST in soybean g. Flaming waterhemp h. Cover crop for waterhemp control (Fall and Spring) Only studies for the objectives Ia and IIa wereconducted for this reporting period: 1.1.Confirmation and characterization of glyphosate-resistant giant ragweed in Nebraska. Field experiments wereconducted in 2014-15 in David City, NE at a site with suspected GR giant ragweed population. Dose response studies will have five glyphosate rates (0, 1X, 4X, 8X, and 16X) applied postemergence (POST) at three different growth stages (4", 8", and 12")(Table 1). Weed control will be assessed visually at 7, 14, and 21 days after treatment (DAT) using a scale ranging from 0 (no weed control) to 100% (complete weed control). The resistance level was calculated by dividing ED90 (90% control) value of herbicide by respective labeled rate of 22oz/A of glyphosate. In addition, giant ragweed control with Saflufenacil and Dicamba wasalso conducted. Dose response studies will include a label rate of glyphosate (22 oz/A) tank-mixed with four saflufenacil or dicamba doses (0, 0.5X, 1X, 2X, and 4X) applied early postemergence (EPOST) at three different growth stages (4", 8" and 12") (table1). Visual weed control will be estimated 7, 14, and 21 DAT. 2.1. Field studies to confirm HPPD-resistant in common waterhemp in Nebraska. Field studies wereconducted during 2015 at a local field with suspected HPPD resistance in Madison County, NE. The plants weresprayed with various doses of mesotrione including 0, 1x, 2x, 4x, and 8x of label rates at an average plant height reached of 3, 6, and 12 inches. Similarly, for 6 and 12 inch tall waterhemp, with Laudis and Impact. Then Visual control will be given ratings at 1, 2 and 3 WAT (week after treatment) on a scale of 0 to 100, with 0 is the appearance of untreated plants and 100 is the full control of waterhemp. At 4 WAT, aboveground fresh biomass weight and dry weight of each pot will be taken and expressed as the percentage of the plant biomass of untreated pots. The design of the experiment is completely randomized design. Then the data will be subjected to ANOVA and the dose response calculated by the equation: Y= d/ (1 + exp b [log(x) - log(e)]). That was used to calculate the 50% reduction in waterhemp shoot fresh weight (GR50) using R statistical software (Knezevic et al. 2007; R Development Core Team 2006). Here, 0 was the lower limit, d the upper limit, e the GR50, GR90 value, and b represents the slope. RESULTS: 1.1.Confirmation of glyphosate-resistant giant ragweed in Nebraska. Suspected GR giant ragweed populations were fieldtested and resistance was confirmed to be at the 12-16X level (x=label rate). This information was shared during Field Days, thus Nebraska farmers are madeaware of this problem. In addition,Saflufenacil and Dicamba ware tested. Addition of dicamba to glyphoste signficantly improved control of ragweed. However, addition offlufenacil to glyphosate did not improve controlgiant ragweed. 2.1. Field studies to confirm HPPD-resistant in common waterhemp in Nebraska. Field studies confirmed theHPPD resistance in waterhemp to be at 6-12X of the label rate (x-label rate). The highestresistance level was confirmed tomesotrione (Callisto) at 12X level, regardless of the plant height. Resistance toLaudis and Impact herbicides was confirmed at 6X and 9X levels, respectfully.
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