NCERA_old184: Management of Small Grain Diseases
(Multistate Research Coordinating Committee and Information Exchange Group)
NCERA_old184: Management of Small Grain Diseases
Duration: 10/01/2012 to 09/30/2017
Statement of Issues and Justification
Small grains, particularly wheat, barley, and oats are significant crops in many states east of the Rocky Mountains - hereafter referred to as eastern U.S. (source: USDA-NASS). Of these, wheat is the most economically important and multiple classes are grown in this region, including: hard red winter (southern and central Great Plains), hard red spring and durum (northern Great Plains), soft red winter (central and southeastern U.S.), and soft white winter (northeast and north central U.S.). There has also been an increase in acreage of hard white wheat planted in the Great Plains with the release of improved varieties. Barley, oats, and to a lesser extent rye and triticale are also regionally important in the eastern U.S. and represent significant crops in certain states (e.g. barley in North Dakota, oats in South Dakota and Oklahoma).
The combined value (farm gate) in 2010 for the grain from these crops was approximately $13.6 billion (source: USDA-NASS). The primary uses of these grains are: human consumption (flour, bran, etc.), livestock feed, and malting and brewing (barley). These crops may also be used for hay, straw, and silage production or even directly grazed (e.g. dual-purpose, graze-grain wheat). Additionally, small grains are being investigated for potential use in biofuel production as both grain-starch and cellulosic sources because they can often be grown in areas where corn and soybeans cannot, for example, winter wheat in the western Great Plains.
Production of small grains has declined substantially over the last 20 years in the United States for several reasons. First, the price paid for grain has changed little during that time and thus the value for several of these crops has actually declined when adjusted for inflation. To add to the financial issues, government subsidies for many of the small grains are less competitive than those for other crops like corn and soybean. Second, diseases continue to have a profound and negative affect on both grain yield and quality and shifts in agronomic practices have complicated disease management strategies further (see below), making it difficult to maintain profitability. Third, the massive expansion of genetically modified (GM) crops (i.e. corn and soybeans) has made small grains much less attractive to producers because of the relatively more complicated and expensive weed and pest management strategies sometimes required for small grains. Finally, small grains are currently less efficient than corn for biofuel (ethanol) production. When all of the above factors are considered, small grains are simply less competitive economically than corn and soybean for much of the eastern U.S. and thus their acreage has gradually declined.
Interestingly, several of these same factors may result in a future increase in the acreage planted with small grains. First, the increasing development of glyphosate (i.e. Round-Up) resistance in corn and soybean is causing a shift in the sensitivity of some weeds to this herbicide and a loss of sensitivity in others. This will complicate future weed management strategies in these crops. Second, the lack of crop diversity has resulted in very short rotations (essentially a monoculture) that allow pest and pathogen populations to remain high and regularly impact yield. Thus, the management of weeds, diseases, and insects in crops presently used as alternatives to small grains is becoming more difficult and expensive. Finally, the increasing costs of fertilizer and fuel, and scarcity of irrigation water in some regions is making it difficult for producers to maintain profitability, especially for corn. A recent development that may also impact production of small grains is that the rapid expansion of biofuel generation using corn and soybean is diverting the grain from these crops away from human and livestock consumption. Small grains may be used to fill the niche left from the biofuel-associated changes in crop utilization as well as for biofuel production directly. Overall, the addition of small grains to current rotations would add diversity to the dominant cropping systems and potentially reduce the impact and severity of the pathogens and pests of all crops.
The agronomic practices utilized for growing small grains have changed dramatically in the last three decades as a large percentage of producers are using reduced tillage practices, planting earlier, and using shorter rotations (limited fallow periods) to reduce soil erosion. Many are also more intensively managing their crops by applying higher amounts of fertilizer to maximize economic returns. All of these factors have had profound effects on the incidence and severity of the diseases of small grains. The residue-borne diseases, such as Fusarium head blight (FHB), tan spot and Septoria diseases of wheat, occur annually in much of the eastern U.S. and have increased following the adoption of reduced tillage practices with a significant impact on both crop yield and quality. Epidemics of FHB in particular have devastated the wheat and barley crops in entire regions (e.g. the northern Great Plains), resulting in millions of bushels in lost production, numerous farm and equipment sales, and disruption of entire rural communities. By gaining a better understanding of the epidemiology of the diseases of small grains in both current and emerging production systems, we can develop economically sound management strategies for producers.
In order for producers of small grains to remain profitable while addressing the future needs of consumers, the impact of diseases on crop yield and quality must be mitigated. Unfortunately, this is difficult not only because of changes in agricultural practices but also because many of the pathogens attacking these crops are dynamic in both their geographic distribution and ability to infect cultivars. For example, stripe rust of wheat was more of a curiosity than a concern in the Great Plains prior to 2001. Since then, it has caused regular losses in several states that reach into the millions of bushels and dollars (e.g. widespread epidemics that resulted in significant losses in North America in 2010). Thus stripe rust has quickly become one of the most economically important diseases of wheat in the entire United States. Other rust diseases of small grains, specifically leaf rust of wheat and crown rust of oats, continue to cause significant losses, even after many years of breeding efforts to improve the resistance in commercial varieties.
In contrast to the aforementioned rust diseases, stem rust (caused by Puccinia graminis) has received very little attention from plant pathologists and breeders lately because it has been effectively controlled through stable host resistance and the barberry eradication program (which targeted the alternate host). As a result, a minimal effort has been put into the introgression of novel resistance genes for stem rust into small grains, particularly wheat. Thus a limited number of genes are deployed in the wheat varieties grown over large regions of the United States (e.g. the southern Great Plains) and throughout the world. A strain (Ug99) of P. graminis has been identified in Africa that is virulent on the majority of the wheat and probably barley cultivars grown in the eastern U.S. A concern shared by both small grains researchers and stakeholders is that this strain will follow a similar migration pathway as that of Asian soybean rust or wheat stripe rust and enter the U.S. before wheat and barley breeders have had time to introgress effective resistance genes into commercially acceptable varieties. To complicate the issue further, the introduction of resistance to one disease rarely provides protection to other diseases and may even disrupt established resistance. For example, wheat breeders in much of the eastern U.S. have focused on developing resistance to FHB, an effort that has resulted in the release of several moderately resistant varieties in the past several years. Unfortunately this work has caused the erosion in the level of resistance to stem rust, putting wheat at an increased risk to this potentially devastating disease. In summary, the combination of a susceptible crop and little probability of the release of resistant varieties in the next decade places wheat production in much of the U.S. at risk to the potentially devastating impact of a major stem rust epidemic.
Increased emphasis on disease prevention and management will be needed to help small grain producers remain competitive in international markets, to assure an ample supply of high-quality grain for domestic consumption, and to minimize the impact of adverse environmental conditions on small grain production. Given the decline in overall support for research and extension activities related to diseases of small grains, individual states have fewer resources for either research on the diseases of small grains or to provide pertinent information for all diseases attacking these crops through the state supported extension programs.
The exchange of information and coordination of research and extension activities among small grain pathologists and individuals in related research programs in the region east of the Rocky Mountains will facilitate better management of small grain diseases. In addition to increased communication and collaboration among small grains pathologists of the eastern U.S., it is anticipated that this group will interact closely with members of the WERA97 (Diseases of Cereals), the Eastern Wheat Workers, and the Southern Small Grain Workers on common diseases of concern. The groups have recently held joint meetings (e.g. 2009 and 2011) and plan to continue these productive interactions during the next several years.
Facilitate collaborative research on current and emerging diseases of small grains
Promote the exchange of information, techniques, fungicide efficacy results, disease resistant germplasm and pathogen cultures among small grains researchers in order to coordinate the development of integrated management strategies for important diseases
Procedures and Activities
Objective 1. Facilitate collaborative research on current and emerging diseases of small grains. In particular, members of NCERA184 are focused on several core sub-objectives including the integrated management of wheat diseases, fungicide efficacy trials for diseases of small grains, epidemiology and risk management, screening of uniform regional nurseries for resistance to economically important pathogens, and studies of the population biology of small grain pathogens. These continue to be the core of our group as they provide a mechanism for sustained efforts to best address the needs of stakeholders and also provide a framework for joint efforts (research and/or through discussions and meetings) with the following groups: WERA97 (Diseases of Cereals), Eastern Wheat Workers, and Southern Small Grain Workers. Furthermore, several of our objectives have also been recognized by other groups, including the Corn Disease Working Group and NCERA212 (Soybean Diseases) as models for ways to provide stakeholders the most relevant disease-related information.
a. Integrated Management of Wheat Diseases.
Studies have been conducted, and will be continuing, using a multi-state, multi-year coordinated mechanism to examine the impacts of i) previous crop residues (corn, wheat, soybean, etc.), ii) level of varietal resistance, iii) fungicide applications, and iv) environmental conditions (especially temperature and relative humidity) on the severity of Fusarium head blight (FHB) in wheat and barley and the contamination of grain with mycotoxins, particularly deoxynivalenol. Research to date has shown that combinations of cultivar resistance with properly-timed fungicide applications reduce the risk of both FHB and deoxynivalenol. The continuation of such trials is important as they directly tie in with sub-objective (c) as a mechanism to improve forecasting for FHB in the U.S. Furthermore, several states (Ohio, Illinois, Indiana, Wisconsin) have commenced with coordinated trials with an explicit goal to develop thresholds for diseases like Stagonospora leaf blotch using combinations of cultivar resistance and fungicide timing.
b. Fungicide Efficacy Trials for Diseases of Small Grains.
Questions continue to be received regarding efficacy of fungicide products currently registered for control of diseases of small grains. As new products obtain approval through EPA, we need to be at the lead for providing stakeholders the best information possible regarding relative efficacy of such products. There has been coordinated effort through the U.S. Wheat and Barley Scab Initiative to conduct coordinated trials for Fusarium head blight, however; the majority of NCERA184 members also conduct fungicide efficacy trials for the small grains pathogens of economic importance in their states. These trials are important for several reasons, including the ability to provide EPA with necessary information for emergency registration of products (Section 18, for example tebuconazol). Most importantly, and as highlighted earlier in the paragraph, data from these trials are integrated into an annual update on fungicide efficacy. This latter output is an approach that both the Corn Disease Working Group and NCERA212 (Soybean Diseases) are considering following to provide producers with similar information in those crops, respectively.
c. Epidemiology and Risk Management
Members of the NCERA184 have collaborated on the development of Fusarium head blight risk assessment models. The risk assessment models are currently deployed in 30 states through a web interface (http://www.wheatscab.psu.edu/). In 2011, the NCERA184 committee enhanced the function of the disease prediction effort by establishing the FHB Alert System. The FHB Alert System sends commentary developed by disease specialists in each state to stakeholders via regional e-mail lists and text messages. These commentaries describe the current risk of disease and often provide management recommendations where appropriate. The value of this system can be seen by the fact that there were approximately 13,000 visits to the web-based prediction tools and more than 800 subscribers to the FHB Alerts during the growing season in 2011. Survey work has indicated that the value of this prediction system to U.S. wheat growers is greater than $47 million annually. As indicated earlier, the ability to link coordinated research trials [sub-objective (a)] with the risk assessment models enables real-time validation of the model, thus providing researchers with mechanisms to examine and continue to improve model accuracy. Key advances that are continuing on the model development and refinements include enhancements to the web-based tools and smart phone applications that enable producers and other stakeholders the opportunity to access risk information in the field.
d. Screening of Uniform Regional Nurseries for Resistance to Economically Important Pathogens.
Members of the NCERA184 work closely with wheat geneticists and breeders in the identification, evaluation, genetics, introgression, and/or deployment of additional or novel sources of resistance to many of the small grains pathogens (e.g. soilborne wheat mosaic virus, Fusarium head blight, leaf rust). A substantial proportion of this effort involves the evaluation of Uniform Regional Nurseries, or similar collaborative screening arrangements like cultivar performance trials. We propose to continue to work closely with small grains breeders and evaluate such collaborative screening nurseries in order to identify and characterize disease resistance in advanced breeding lines. This has multiple benefits, including integration with sub-objectives (a) and (c) in terms of developing best management practices for small grain diseases as well as validation of forecasting risk models. Furthermore, this provides a mechanism for screening for resistance to new diseases or strains of existing pathogens such as the Ug99 strain of wheat stem rust, thus providing a link with sub-objective (e).
e. Studies of the Population Biology of Small Grains Pathogens.
The monitoring of the population biology of the pathogens of economic importance to small grains is extremely important as this provides a mechanism to identify changes in these populations that may impact the stability of resistance present in the cultivated varieties. Additionally, this information can be used to provide input for the prioritization of resistance introgression into adapted varieties and help guide varietal improvement programs overall. Furthermore, this provides a coordinated, national level system to look for exotic strains, such as the Ug99 strain of wheat stem rust. In collaboration with USDA-ARS scientists (Y. Jin, J. Kolmer, and X. Chen), samples of the major rust diseases of the small grains (e.g. leaf rust of wheat, crown rust of oats, etc) will be collected and submitted for race determination and other purposes. This project has been on-going for decades and represents a major effort to monitor the population/virulence structure of these extremely important and often yield limiting pathogens.
Objective 2. Promote the exchange of information, techniques, fungicide efficacy results, disease resistant germplasm and pathogen cultures among small grain researchers in order to coordinate the development of integrated management strategies for important small grain diseases.
Members of the NCERA184 have a documented history demonstrating effective information exchange through the annual committee meeting and through national and regional plant pathology meetings. Furthermore, we maintain coordinated email discussions, including the wheat disease listserv (firstname.lastname@example.org) and cereal rust survey listserv (email@example.com). We have shown a desire to meeting jointly with sister programs such as WERA97 and the Eastern Wheat Workers and Southern Small Grain Workers and propose to continue to meet jointly with those groups when possible. Furthermore, as an example, we have taken the initiative to conduct our next meeting as part of the International IPM Symposium to be held in Memphis, TN in March 2012. As part of that program, we have proposed and had accepted a special session on advances in the biology and management of Fusarium head blight. Our information delivery mechanisms continue to be refined and improved, such as ScabSmart and the proposed development of smart phone applications for Fusarium head blight predictions. Lastly, our approaches are being emulated by other groups such as the Corn Disease Working Group and NCERA212 (Soybean Diseases).
Expected Outcomes and Impacts
- Coordinate research programs to identify management practices that work synergistically to limit the impact of Fusarium head blight of wheat and barley. Develop and promote integrated strategies for management of wheat diseases to producers
- Continue evaluation of new fungicide chemistries to find more efficacious products that can be incorporated into integrated strategies for managing wheat diseases. Promote integrated strategies for disease management to reduce unnecessary fungicide use.
- Refine risk assessment models that can be used in disease management regimes to increase producer productivity and profitability while maintaining crop quality.
- Identify germplasm and advanced breeding lines that are disease resistant, and use them in the development of commercial varieties with improved disease resistance.
- Monitor the development and migration of highly virulent or aggressive pathogen strains (e.g. virulent Puccinia species, highly toxigenic chemotypes of Fusarium graminearum, etc).
- Outcome/Impact 6. Publish joint research articles and extension bulletins on common diseases. Outcome/impact 7. Developing and promoting an integrated approach to disease management will result in the reduction of unnecessary fungicide applications and improved control of important wheat pathogens. Outcome/Impact 8. Disease resistant germplasm and advanced breeding lines will be identified that will be used in the development of commercial varieties with improved disease resistance. Outcome/Impact 9. Information about the appearance and distribution of virulent or aggressive pathogen strains will allow for better prioritization of varietal improvement efforts and rapid responses to emerging disease threats. Outcome/Impact 10. Most states have experienced staffing cuts in extension and have fewer dollars to produce extension materials. Developing bulletins that could be used regionally helps conserve individual state resources while providing consistent information throughout production regions. Outcome/Impact 11. The overall impact of these activities will result in improved yields for small grain crops in the region. In turn, this will allow producers to maintain profitability while growing small grains and offer additional rotational choices for primary crops in the region (i.e. corn and soybeans). By having a more diverse rotational scheme, the impacts of pests and diseases on all crops will be reduced, allowing these agricultural systems to remain or become sustainable.
Projected ParticipationView Appendix E: Participation
We will disseminate information to the scientific community, growers, consultants and other agriculture industry personnel via a variety of means including: extension and risk forecasting websites, newsletters, email (e.g. listservs), grower-meetings, and publication of multi-state extension bulletins.
Currently, two primary listservs exist (wheat disease listserv and cereal rust survey listserv) that enable collaboration and discussion amongst NCERA184 researchers. These are important components for discussing real-time issues in disease diagnostics or other observations in the small grain production areas.
Information pertaining to wheat diseases needs to be conveyed to the wheat production sector on a timely and cost effective basis. For example, the Penn State web page which provides a prediction tool for Fusarium head blight has expanded its coverage and accessibility to growers and crop consultants. Recently, ScabSmart was developed with the support of the U.S. Wheat and Barley Scab Initiative. Numerous members of NCERA184 participate in both efforts to provide best management practices and state specific commentary regarding the risk of FHB. New plans include the completion of smart phone tools for accessing risk information in the field.
Most states have a weekly online or print extension newsletter. Technologies such as the internet, online bulletins, print on demand and grower hotlines are all methods that will be used to transmit disease management information quickly and effectively to producers. The majority of the infrastructure required for this activity is currently available through state-level extension services as well as federally funded projects (e.g. the US Wheat and Barley Scab Initiative, the USDA-CSREES PIPE, etc.) and we will continue to look for funding to continue such efforts.
There will be two officers for NCERA-184. A secretary will be elected at each annual meeting. The secretary records and distributes minutes of the annual meeting, submits the annual report, and then becomes chair of the committee for the following year. The chair directs the activities of the committee, serves as the liaison between the committee and the administrative advisor, and assists with or directs arrangements for the next annual meeting.