Source: UNIVERSITY OF MISSOURI submitted to NRP
GLYPHOSATE-RESISTANT COMMON RAGWEED: DEVELOPMENT OF CROP MANAGEMENT SYSTEMS TO REDUCE SOIL SEED-BANK POPULATIONS AND IDENTIFICATION OF POTENTIAL FOR RAGWEED SPREAD BY POLLEN
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
HATCH
Reporting Frequency
Annual
Accession No.
0233863
Grant No.
(N/A)
Cumulative Award Amt.
(N/A)
Proposal No.
(N/A)
Multistate No.
(N/A)
Project Start Date
Feb 1, 2013
Project End Date
Jan 31, 2018
Grant Year
(N/A)
Program Code
[(N/A)]- (N/A)
Recipient Organization
UNIVERSITY OF MISSOURI
(N/A)
COLUMBIA,MO 65211
Performing Department
Plant Sciences
Non Technical Summary
Weeds are one of three major pests that crop producers must manage in their fields, and more money is spent annually on chemicals for control of weeds (herbicides) than all other pesticides combined. Continued use of herbicides year after year will eventually result in weed populations that develop resistance, forcing crop producers to adopt other weed management practices. In recent years, herbicide manufacturers have produced fewer and fewer new chemicals. Alternatively, herbicide manufacturers have developed techniques to genetically modify corn and soybean to exhibit resistance to very effective and economic herbicides (e.g. glyphosate). Glyphosate resistance in corn and soybean has become so successful that over 90% of the soybean area and 60% of the corn area now produce glyphosate-resistant crops. Unfortunately, widespread use of this technology has resulted in the evolution of glyphosate-resistant common ragweed. The research in this proposal seeks to find alternative practices to manage glyphosate resistance, and also determine if resistance can spread to other areas through the pollen of resistant common ragweed. This can serve as a model for managing other resistant weeds that are appearing.
Animal Health Component
(N/A)
Research Effort Categories
Basic
(N/A)
Applied
(N/A)
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
21323001140100%
Knowledge Area
213 - Weeds Affecting Plants;

Subject Of Investigation
2300 - Weeds;

Field Of Science
1140 - Weed science;
Goals / Objectives
Identify different techniques to manage glyphosate-resistant weeds such as common ragweed and also determine how pollen can transmit glyphosate resistance to neighboring plants.
Project Methods
Field-based research using approved statistical designs will be established over a multi-year period. In one set of large plot studies, herbicide programs and crop rotations will be combined over a 4 year period to determine the affect on common ragweed density. Once per year, the soil will also be sampled and the common ragweed seed elutriated and counted to determine the contribution of chemical programs and cropping systems to seeds entering the soil seedbank. Crops will be planted and herbicides will be applied using commonly accepted practices. For the pollen transmission studies, sentinel glyphosate-susceptible plants will be established in pots at different distances from known glyphosate-resistant plants. The pots of plants will be placed in groups in an arc from resistant plants, with all plants surrounded by soybeans (simulating a crop field). All plants will be allowed to cross and seed will be collected, with progeny tested in a controlled greenhouse environment for glyphosate-resistance.

Progress 10/01/17 to 01/31/18

Outputs
Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Field studies were conducted to identify the frequency and distance that the trait for glyphosate-resistance (GR) in an identified population of common ragweed (Ambrosia amremisiifolia L.) could be spread by pollen. A population of GR common ragweed was established in pots in the spring in a rectangular area. A series of glyphosate-susceptible (GS) common ragweed were established in semi-circles in a dominant down-wind distance (1 to 580 meters) from GR common ragweed. All other ragweed plants were controlled in the experimental area. Common ragweed seed was harvested from all GR and GS plants in the fall and vernalized to break seed dormancy. Seeds were planted in flats containing soil in a greenhouse setting. As plants reached 10 cm in height, all plants were treated with glyphosate at 1.68 kg ae.ha-1 and evaluated for injury as one of three groups: 0-30% visual injury [resistant]; 31-89% visual injury [intermediate]; and 90-100% visual injury [susceptible]. Results indicate glyphosate resistance was present among seed from GS plants at several points at distances up to 91 meters from GR plants. In one instance, one GR plant was identified up to 198 meters from GR plants. The only mechanism that could have resulted in generation of GR progeny from GS plants was transfer of pollen from GR plants and successful fertilization of GS plants.

Publications

  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Korres, N.E., J.K. Norsworthy, B.G. Young, D.B. Reynolds, W.G. Johnson, S.P. Conley, R.J. Smeda, T.C. Mueller, D.J. Spaunhorst, K.L. Gage, M. Loux, G.R. Kruger, and M.V. Bagavathiannan. 2018. Seedbank persistence of Palmer amaranth (Amaranthus palmeri) and waterhemp (Amaranthus tuberculatus) across diverse geographical regions in the United States. Weed Sci. 66:446-456.
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Spaunhorst, D.J., P. Devkota, W.G. Johnson, R.J. Smeda, H.R. Davis, C.J. Meyers, J.K. Norsworthy. 2018. Phenology of five Palmer amaranth (Amaranthus palmeri) populations grown in northern Indiana and Arkansas. Weed Science. 66:457-469.


Progress 02/01/13 to 01/31/18

Outputs
Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Field studies were conducted to identify the frequency and distance that the trait for glyphosate-resistance (GR) in an identified population of common ragweed (Ambrosia amremisiifolia L.) could be spread by pollen. A population of GR common ragweed was established in pots in the spring in a rectangular area. A series of glyphosate-susceptible (GS) common ragweed were established in semi-circles in a dominant down-wind distance (1 to 580 meters) from GR common ragweed. All other ragweed plants were controlled in the experimental area. Common ragweed seed was harvested from all GR and GS plants in the fall and vernalized to break seed dormancy. Seeds were planted in flats containing soil in a greenhouse setting. As plants reached 10 cm in height, all plants were treated with glyphosate at 1.68 kg ae.ha-1 and evaluated for injury as one of three groups: 0-30% visual injury [resistant]; 31-89% visual injury [intermediate]; and 90-100% visual injury [susceptible]. Results indicate glyphosate resistance was present among seed from GS plants at several points at distances up to 91 meters from GR plants. In one instance, one GR plant was identified up to 198 meters from GR plants. The only mechanism that could have resulted in generation of GR progeny from GS plants was transfer of pollen from GR plants and successful fertilization of GS plants.

Publications


    Progress 10/01/16 to 09/30/17

    Outputs
    Target Audience:Crop producers, University Extension Specialists, Agricultural Industry Professionals. Changes/Problems:There were no major problems associated with the research. What opportunities for training and professional development has the project provided?Students have prepared and participated in University sponsored field days. In addition, research results were presented via oral presentations and posters at the North Central Weed Science Society meeting in Milwaukee, WI. Finally, weed science students participated at a summer contest in Nebraska where students could demonstrate skills in weed identification, herbicide injury, and sprayer calibration. How have the results been disseminated to communities of interest?Students in our program have participated in field days to inform growers and industry professionals of research accomplishments. What do you plan to do during the next reporting period to accomplish the goals?Initiate research with off-target movement of dicamba and understand the basis for movement. A new 5 year plan will be prepared to identify important research foci.

    Impacts
    What was accomplished under these goals? Off-target movement of dicamba Dicamba-tolerant soybeans and cotton were planted on 20 and 8 million acres, respectively in 2017. Across the Mid-west, there were widespread reports of off-target movement of dicamba from treated fields to adjacent dicamba-sensitive soybeans. Visibility of damage symptoms on sensitive soybeans can occur at very low concentrations. However, the relationship between crop injury and resulting crop yields is not clear at low dicamba concentrations. Initial results suggest yields of sensitive soybean were reduced up to 8% with as little as 10 parts per million (ppm) dicamba and as much as 49% with 300 ppm dicamba. At the same dicamba concentration, soybean yields were reduced an additional 10% for plants treated flowering (R1) versus vegetative stage (V3). Off-target movement of as little as 0.025% of the labeled rate of dicamba can result in significant yield losses to sensitive soybean. Sensitivity of established grapes to chemical trespassing of dicamba Adoption of dicamba-tolerant soybeans has led to widespread dicamba applications. In Missouri, grape production occurs in many areas with concentrated soybean production. It is widely known that grapes are extremely sensitive to growth regulator herbicides such as dicamba. However, exposure of field established grapes to dicamba is not known, and the impacts over multiple years has not been studied. Therefore research was established at 2 locations in 2017 to determine the growth and reproductive impact of dicamba on 'Vidal blanc' grapes. Vines were exposed to particle or vapor drift of dicamba at rates <0.1% of field application rates. The timing of exposure was flowering grapes (corresponds to pre-plant applications of dicamba) and early fruit set (corresponds to early postemergence applications of dicamba. Visual injury on grapes exposed to 36 or 72 ppm dicamba as vapor to particle drift was 19-72%. Meristematic shoot growth was reduced by 10-100% at these same rates of dicamba. Grape yields were reduced up to 30% by dicamba, but results were highly variable. However, measurements of grape berry sugar levels (BRIX) suggested that dicamba significantly reduced sugar levels, which can impact the quality of the grapes.

    Publications

    • Type: Journal Articles Status: Accepted Year Published: 2017 Citation: Spaunhorst, D.J., P. Devkota, W.G. Johnson, R.J. Smeda, C.J. Meyer, and J.K. Norsworthy. Phenology of five Palmer amaranth (Amaranthus palmeri) populations grown in northern Indiana and Arkansas. Weed Sci.
    • Type: Journal Articles Status: Accepted Year Published: 2017 Citation: Fernandez-Moreno, P.T., R.J. Smeda, R. DePrado. Differential resistance mechanisms to glyphosate result in fitness cost for Lolium perenne and L. multiflorum. Frontiers in Plant Science.
    • Type: Journal Articles Status: Accepted Year Published: 2017 Citation: Korres, N.E., J.K. Norsworthy, B.G. Young, D.B. Reynolds, W.G. Johnson, S.P. Conley, R.J. Smeda, T.C. Mueller, D.J. Spaunhorst, K.L. Gage, M. Loux, G.R. Kruger, M.V. Bagavathiannan. Weed Sci.
    • Type: Theses/Dissertations Status: Accepted Year Published: 2017 Citation: A.J. Luke. M.S. Tank Contaminant and Residual Effects of Dicamba. 68 pp.


    Progress 10/01/15 to 09/30/16

    Outputs
    Target Audience:Crop producers, University Extension Specialists, Agricultural Industry Professionals. Changes/Problems:There were no major problems associated with the research. However, the rapidly changing agricultural landscape involving adoption of dicamba-tolerant crops to control glyphosate-resistant weeds has created a need to conduct research with off-target movement. What opportunities for training and professional development has the project provided?Students have prepared and participated in University sponsored field days. In addition, research results were presented via oral presentations and posters at the North Central Weed Science Society meeting in St. Louis. Finally, weed science students participated at a summer contest in Nebraska where students could demonstrate skills in weed identification, herbicide injury, and sprayer calibration. How have the results been disseminated to communities of interest?Students in our program have participated in field days to inform growers and industry professionals of research accomplishments. What do you plan to do during the next reporting period to accomplish the goals?Initiate research with off-target movement of dicamba and understand the basis for movement.

    Impacts
    What was accomplished under these goals? Dicamba contaminants in spray equipment. Dicamba-tolerant soybeans and cotton will be released across the U.S. in 2017. Soybeans are highly sensitive to dicamba, and the potential for rinsates from spray equipment applying dicamba to reach sensitive soybeans is a concern. Collaborative research with a large Farmer based Co-op (MFA Inc.) was established to simulate dicamba application through two different commercial applicators. The equipment was cleaned with water, ammonia, or 2 different commercial cleaners. Spray rinsates were quantified for dicamba and applied to sensitive soybeans. Initial results suggest sensitive soybeans exhibited 6 to 39% visual injury from spray rinsates containing dicamba. Soybeans exposed during vegetative growth (V3) recovered, but soybeans during initial flowering (R1) continued to exhibit injury. Soybean height reductions of up to 29% were noticeable at both growth stages (V3 and R1). Soybean yields were up to 11 and 46% for soybeans exposed at V3 and R1, respectively compared to untreated plants. Proper cleaning of spray equipment containing dicamba is critical to minimizing damage dicamba-sensitive soybeans. Explore the use of herbicides for control of invasive Callery pear Callery pear was introduced into the U.S. from China in 1916 to use genetic material for breeding fire blight (devastating disease) resistance into commercial pears. Ornamental qualities such as flowering and fall foliage with Callery pear led to development of cultivars such as 'Bradford' that were widely sold to the public. However, close proximity of 'Bradford' pear to other cultivars has resulted in fruit and seed development. Winter foraging birds have consumed fruit and spread viable seed to meadow and forest habitats. The result is widespread populations of an invasive hybrid pear. These invasive trees are displacing native trees and threaten to take over wooded areas. No commercial herbicides have been studied for control of Callery pear because plants were considered ornamentals. Field research shows that glyphosate and a wide range of ALS inhibiting herbicides and growth regulators are effective when applied to 2 meter trees during mid-summer. Applications of concentrated herbicides are effective when applied to cut stumps.

    Publications

    • Type: Journal Articles Status: Submitted Year Published: 2017 Citation: Spaunhorst, D.J., P. Devkota, W.G. Johnson, R.J. Smeda, C.J. Meyer, and J.K. Norsworthy. Phenology of five Palmer amaranth (Amaranthus palmeri) populations grown in northern Indiana and Arkansas. Weed Sci.
    • Type: Journal Articles Status: Submitted Year Published: 2017 Citation: Fernandez-Moreno, P.T., R.J. Smeda, R. DePrado. Differential resistance mechanisms to glyphosate result in fitness cost for Lolium perenne and L. multiflorum.


    Progress 10/01/14 to 09/30/15

    Outputs
    Target Audience:Crop producers, University Extension Specialists, Agricultural Industry Professionals. Changes/Problems:There were no significant changes or problems related to the attempted research. What opportunities for training and professional development has the project provided?Both J.D. Bolte and H.R. Davis were able to complete their M.S. degrees and are employed in the agricultural industry. How have the results been disseminated to communities of interest?Yes, the thesis was disseminated to the scientific community as were the publications. Field day presentations were given to update the growers, extension specialists, and industry professionals. What do you plan to do during the next reporting period to accomplish the goals?Continue to pursue weed management systems of Amaranthus and explore a new tool (dicamba) for weed management.

    Impacts
    What was accomplished under these goals? Horseweed: Changes in climate have impacts on the emergence timing of weeds, which has implications for weed management in crops. Horseweed (Conyza canadensis) is traditionally a winter annual weed. Selection for resistance by overuse of the herbicide glyphosate has resulted in many resistant populations throughout the agronomic crop productions areas in the Midwest and mid-south. Seed from populations of horseweed across 12 locations throughout Missouri were collected and fall planted in central and southeast Missouri. Emergence was followed over a 10 month period. Over a 2 year period, from 4.1 to 68.2% of horseweed emerged in the fall, with the remaining seedlings emerging in the spring. This is a departure from reports in the literature where over 80% of horseweed emerges in the fall. Research determined that weather conditions influence horseweed emergence, with a significant percentage of seedlings emerging over a 10 month period. Management of horseweed must now consider this species to be both a winter and summer annual weed. Waterhemp and Palmer amaranth: Amaranthus spp. germination occurs at a higher level under no-till versus conventional tillage conditions. Up to 90% of Amaranthus germination occurs within 45 days after the first seedlings emerge in the spring (early May for waterhemp in central MO; late April for Palmer amaranth in southeast MO). Over a 2 year period, waterhemp and Palmer amaranth reached a mature plant height of 1.8 meters; maximum seed production was higher for waterhemp (800,000 per plant) versus Palmer amaranth (700,000 seeds per plant). Seedlings of both waterhemp and Palmer amaranth emerged within 30 days of a fall frost; seedlings produced up to 45 viable seeds. Implications of this research are that early season management of Amaranthus species is necessary to preclude competitive losses with agronomic crops such as soybean and corn. However, later season emergence of Amaranthus are sufficient to recharge soil seed bank populations.

    Publications

    • Type: Journal Articles Status: Published Year Published: 2016 Citation: Alcantara, R., P. Fernandez, R.J. Smeda, P.L. Alves and R. DePrado. Response of Eleusine indica and Paspalum distichum to glyphosate following repeated use in citrus groves. Crop Protection.
    • Type: Theses/Dissertations Status: Published Year Published: 2015 Citation: J.D. Bolte. Emergence and control of horseweed (Conyza canadensis). M.S. Thesis. 142 p
    • Type: Theses/Dissertations Status: Published Year Published: 2015 Citation: H.R. Davis. Emergence pattern of Amaranthus spp. and impact on growth and reproduction. M.S. Thesis. 147 p.


    Progress 10/01/13 to 09/30/14

    Outputs
    Target Audience:Crop producers, University Extension Specialists, Agricultural Industry Professionals. Changes/Problems:Our long-term field study to examine changes in soil seed bank populations of Ambrosia artemiisifolia) were stopped when the owner of the property died and the property was farmed by someone that did not want us to continue working. What opportunities for training and professional development has the project provided?T. C. Shauck was able to complete his Ph.D. Dissertation. How have the results been disseminated to communities of interest?Yes, the thesis was disseminated to the scientific community as were the publications. Field day presentations were given to update the growers, extension specialists, and industry professionals. What do you plan to do during the next reporting period to accomplish the goals?Continue to pursue weed management systems of Amaranthus and explore a new tool (dicamba) for weed management.

    Impacts
    What was accomplished under these goals? Crop management: Weed management in corn is also a challenge when corn is followed by corn. Glyphosate-resistant volunteer corn can be difficult to manage with herbicides in a field with planted glyphosate-resistant corn. Research determined that small inefficiencies in corn harvest can leave significant populations of corn that can be competitive when the following crop is corn. In vitro pollen assay: Pollen of Amaranthus spp. were germinable under in vitro conditions The target enzyme of glyphosate, namely EPSP synthase, is present in Amaranthus pollen A dose-response of Amaranthus pollen to glyphosate was identified, although the response curve did not follow the same shape as that for whole plants.

    Publications

    • Type: Journal Articles Status: Published Year Published: 2014 Citation: Shauck, T.C. and R.J. Smeda. Competitive effects of hybrid corn (Zea mays) on replanted corn. Weed Technol. 28:685-693.
    • Type: Journal Articles Status: Published Year Published: 2014 Citation: Shauck, T.C. and R.J. Smeda. In vitro pollen tube growth of glyphosate-resistant and susceptible Amaranthus in response to glyphosate. Pesticide Biochemistry Physiology.
    • Type: Theses/Dissertations Status: Published Year Published: 2014 Citation: T.C. Shauck. Ph.D. IDENTIFICATION OF NONTARGET-SITE MECHANISMS OF GLYPHOSATERESISTANCE IN ROOTS AND POLLEN OF AMARANTHUS AND AMBROSIA


    Progress 02/01/13 to 09/30/13

    Outputs
    Target Audience:Crop producers, University Extension Specialists, Agricultural Industry Professionals. Changes/Problems:Pollen from common ragweed contains many alkaloid compounds that made germination media suitable for pollen very difficult to identify. The emergence of Amaranthus spp. with resistance to the herbicide glyphosate has shifted a portion of the focus of research. What opportunities for training and professional development has the project provided?Permitted Ph.D. student to learn training in another scientist's laboratory to identify germinable pollen under a light microscope. Student also could attend a regional, professional weed science meeting. How have the results been disseminated to communities of interest?Yes, results were shared in the summer at field days attended by growers, extension personnel and industry professionals. What do you plan to do during the next reporting period to accomplish the goals?The Ph.D. student will complete his research and hopes to complete his dissertation.

    Impacts
    What was accomplished under these goals? Critical components of in vitro media to stimulate germination of common ragweed and Amaranthus spp. pollen is difficult to identify. Sucrose, boron, and proper osmotic adjustment are necessary to trigger pollen germination. Pollen of common ragweed is difficult to stimulate for germination, but assay appears to work with glyphosate-resistant Palmer amaranth A germination assay in the presence of different concentrations of glyphosate is underway.

    Publications

    • Type: Journal Articles Status: Published Year Published: 2013 Citation: Rosario, J.M., H. Cruz-Hipolito, M.D. Osuna, R.J. Smeda and R. DePrado. Resistance mechanism to tribenuron-methyl in white mustard (Sinapis alba L.) from southern Spain. Weed Sci. 61:341-347.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Shauck, T.C. and R.J. Smeda. Amaranthus species: pollen expression of EPSP synthase and in vitro pollen germination. Proc. North Central Weed Sci. Soc. 68:131.