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Funded Project |
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Funding Program:
IPM Enhancement Grants |
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Project Title:
Frequency of Known and Possible New Viruses Infecting Wheat in Oklahoma
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Project Director (PD):
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Lead State: OK Lead Organization: The University of Tulsa |
| Undesignated Funding: $29,999 |
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Start Date: Mar-01-2016 End Date: Feb-29-2016 |
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No-Cost Extension Date: Jul-01-2017 |
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Pests Involved: Viruses |
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Site/Commodity: Wheat |
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Area of Emphasis: Ecology, Epidemiology |
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Summary:
Viruses are a continuous threat to agricultural crops worldwide. The main goal of this project is to determine the number and type of viruses infecting wheat in Oklahoma. Wheat (Triticum aestivum L.) is one of the main commodities in the United States (US) grown for both grain and forage. Wheat is affected by a number of diseases that cause significant yield losses worldwide. Diseases caused by viral pathogens are a major threat to the sustainable production of wheat in the US.
In Oklahoma, wheat is the leading cash crop, and contributes more than six hundred million dollars annually to the states economy. Few viruses have been reported to infect wheat crops but substantial data are lacking on the number of viruses infecting wheat and their spatial and temporal analysis. The main goals of this work are to identify and determine the frequency of viruses that are known to infect wheat and to identify the emergence of new viruses that might infect Oklahoma wheat but for which no information is available. Understanding the ecology, biology, evolution and transmission strategies of viruses can lead to insights and interventions for effective crop disease management. It is important to be a step ahead of the virus diseases to prevent possible epidemic outbreaks that threaten our food biosecurity and agriculture in Oklahoma. Plant viruses have very high mutation rates and appear to be the fastest-evolving plant pathogens; thus they cause tremendous crop losses annually. Currently, plant viruses are often ignored as they are difficult to detect because the infected host may not display symptoms or the symptoms may closely resemble those of various physiological disorders or genetic abnormalities. Information obtained in this project will impact our awareness and knowledge about viruses infecting wheat in Oklahoma, which could be used in future management strategies against viruses in wheat. The results obtained in this project will be communicated to the research community and directly to the growers via the education of county extension agents and giving them technical advice during their dissemination of the information to growers. Objectives: Plant viruses are responsible for reduction in both yield and quality of produce worldwide. Losses caused by plant viruses and the resulting financial damage could be reduced or completely eliminated by controlling epidemics through the use of measures that minimize virus sources, suppress plant susceptibility, or limit spread of a viral infection. A combination of measures including host resistance and biological and cultural control measures have led to the development of integrated management strategies for virus disease. However, detailed knowledge of the epidemiology of the causal agent is necessary in a particular cropping system in order to design effective and long lasting control measures to manage a particular plant virus in a locality. In order to have complete detailed information about the type of viruses infecting wheat in Oklahoma, their possible transmission vectors and over wintering hosts, we propose the following objectives: 1. To carry out state-wide survey for the presence of wheat viruses. Long term outcome: To select resistant cultivars against the virus that is epidemic in nature in wheat crops of Oklahoma. Short term outcome of this objective is to determine how many viruses are out there and which one is the dominant virus that has the greatest potential impact on wheat yield. 2. To identify potential reservoir hosts and presence of insect vectors. Long term outcome: What hosts act as a reservoir for viruses infecting wheat and what sort of vectors are present in the wheat fields which are potential transmitter of wheat viruses? Short term outcomes: Growers will be made aware of the potential hosts and vectors that need to be controlled before or during the wheat season in order to reduce the possible spell over of virus inoculum to wheat fields. 3. To identify known and possible new emerging viruses using various techniques. Long term outcome: Develop effective management strategies for a dominant virus that would impact wheat yields. Short term outcome: Determine the virosphere of wheat in Oklahoma and which virus needs immediate attention to reduce its impact on wheat crops. Avoid unnecessary expenses on input in growing wheat if a particular virus is not present in a particular County of Oklahoma. |
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Final Report: |
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Outputs Surveys were conducted in commercial wheat fields of Oklahoma during the growing seasons of 2015 and 2016 in 33 counties. More than 1,000 symptomatic leaf samples of wheat were collected from grower’s fields in 33 counties. All samples were tested individually by a serological method, [dot-immunobinding assay (DIBA)] against the antiserum of 15 different viruses. Ten out of 15 known viruses were detected in wheat fields, but none of the samples were positive for BSMV, CerCMV, MSV, WDV, and WSSMV. The highest average incidence was recorded for BaMMV (55.9%) followed by WSMV (44.06%), BYDV-PAV (12.6%), BYDV-RPV (7.9%) and HPV (2.09%). The remaining five viruses (BaYMV, BYDV-MAV, SBWMV, JGMV and MCMV) were detected in less than 2% of the samples tested. Mixed infection of two or more than two viruses was also observed in some counties. Several weeds which were commonly observed in wheat fields adjacent to wheat fields of eastern counties of the state. These include, Johnson grass, foxtail, fescue, cheat grass, curly dock, jointed goat grass, barley, wild oats, and ryegrass. None of the weeds were infected with 15 viruses except ryegrass and Johnson grass. Ryegrass samples were positive to BaMMV, BYDV-RPV, SBWMV and MCMV, Cheat was positive to BaMMV and Johnson grass was positive to MDMV. These results showed the presence of two new viruses (MDMV and MCMV) in weeds and wheat that were never reported before. Bird cherry-oat aphids were observed in a few counties that include Ottawa, Blaine and Okmulgee counties. We did not observe any other vectors in wheat fields of various counties during the survey. It is more likely that the growers have sprayed for the vectors or died due to non-conducive environment at the time of survey. The results obtained in this project showed that at least 10 viruses’ commonly infecting wheat crops in Oklahoma. Virus also infect weeds and could act as a reservoir hosts. The results was communicated to growers as well as county extension agents. This knowledge will help them in the integrated management practices of wheat against virus diseases. In addition, growers will also target to get rid of weeds before the wheat season and will eliminate the virus reservoirs to reduce the inoculum pressure on wheat crops. The following publication is the results of this project. Wijayasekara, D and A. Ali*. 2017. First report of Maize dwarf mosaic virus in Johnsongrass in Oklahoma. Plant Disease (Accepted). |
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Outcomes 1. Before the start of this project, Extension educators, and wheat growers have little knowledge what viruses caused diseases in wheat and how the virus-like symptom look like in the wheat plants. 2. There was little information about the number and type of viruses infecting wheat crops in Oklahoma. 3. With the help of this project, more than 30 county extension educators, and wheat growers obtained knowledge about wheat viruses and their potential effect on wheat yield. 4. Based on the information provided about virus’s diseases and their symptoms in wheat fields, I expect that growers are more aware now about virus-like infection. They will spray on weeds to remove the reservoirs of virus inoculum as well as aphid vectors. 5. In the coming season, I am expecting that County educators or wheat growers will contact me about possible virus-like infection if they observed in wheat fields. This will indicate that they are aware of what knew about it. 6. We expect that wheat growers and county extension will easily identify virus infection in wheat than other diseases caused by fungi and other pathogens. Yes, we will measure in future to see what wheat growers have adopted for virus-like diseases. |
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