NCERA_OLD184: Management of Small Grain Diseases
- October 01, 2007 to September 30, 2012
- Administrative Advisor(s):
- NIFA Reps:
Martin A Draper
Statement of Issue(s) and Justification:Small grains, particularly wheat, barley, and oats are significant crops in many states east of the Rocky Mountains (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.). Also, the acreage of hard white wheat planted in the Great Plains has continued to increase in recent years 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 2005 for the grain from these crops was nearly $5.4 trillion (source: USDA-NASS). The primary uses of the grain are: for human consumption (flour, bran, etc.), as 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, the 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 (e.g. winter wheat in the western Great Plains).
The 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 (e.g. corn and soybeans). Second, diseases continue to have a profound 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 dominance of glyphosate (e.g. 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 that allow pest and pathogen populations to remain high and regularly impact yield. Thus, the management of weeds and diseases in crops presently used as alternatives to small grains is becoming more difficult and expensive. Third, these crops are essentially in a monoculture with limited genetic variability making them susceptible to disease epidemics (e.g. Asian soybean rust) or insect pests. 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 two 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 region 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. Texas and Kansas in 2005). 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 of the world. A strain 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 United States. 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 which 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) on common diseases of concern. The groups have recently held joint meetings (e.g. 2006) and have planned joint meetings for the next several years (2007 and 2008).
- Facilitate collaborative research on current and emerging diseases of small grains. Specifically:
a) The Integrated Management of Fusarium head blight,
d) Fungicide Efficacy Trials for Diseases of Small Grains,
c) Epidemiology and Risk Management,
d) Screening of Uniform Region Nurseries for Resistance to Economically Important Pathogens, and
e) Studies of the Population Biology of Small Grains' Pathogens.
- 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 ActivitiesObjective 1. Facilitate collaborative research on current and emerging diseases of small grains
a. Integrated Management of Fusarium head blight (FHB).
A multi-state, multi-year study will be performed to evaluate the impacts and interactions 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 in wheat and barley and the contamination of grain with mycotoxins, particularly deoxynivalenol. This study will be conducted on the major wheat classes in the eastern U.S. (hard red spring and winter, soft red) as well as barley. Crops will be planted in a split-plot design and maintained according to the typical practices utilized in that region. The varieties chosen will include susceptible cultivars commonly planted by producers in each region as well as recently released varieties with moderate levels of resistance. Fungicides will be applied at flowering. Disease assessments will be conducted at the soft-dough stage; the grain will be harvested and then evaluated for scabby kernels and mycotoxin content.
b. Fungicide Efficacy Trials for Diseases of Small Grains.
The majority of NCERA184 members conduct fungicide efficacy trials for the small grains pathogens of economic importance in their region and a proportion of these are coordinated and funded through a common source. Specifically, the U.S. Wheat and Barley Scab Initiative has funded a Uniform Fungicide Trial for the control of Fusarium head blight for over five years. The information generated from this effort has been integral in the emergency (Section 18) registration of tebuconazol (e.g. Folicur) for the control of FHB. As funding permits and when logistically feasible, we will coordinate such efforts for FHB and other diseases (e.g. leaf rust) in order to determine the optimal fungicide actives (or classes) and application rates, timings, and methodologies for specific diseases.
c. Epidemiology and Risk Management
Members of the NCERA184 have collaborated on the development of Fusarium head blight risk assessment models. These are currently deployed in 24 states through a web interface (http://www.wheatscab.psu.edu/) and visited by several thousand producers annually. The models provide producers with information useful in the management of this devastating disease. As funding permits, we will continue refining the currently available models for FHB as well as begin developing models for other major small grains diseases. To accomplish this objective, disease monitoring plots will be planted at pertinent locations and the severity of various disease(s), weather parameters, and dominant local cropping systems will be recorded. Data will be complied and analyzed using the appropriate statistical techniques (e.g. regression analysis). Additionally, the mechanistic modeling of the individual stages of a disease cycle (e.g. spore production in response to environmental conditions) will be conducted for specific pathogens as necessary to produce the most effective models.
d. Screening of Uniform Region 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. We will 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. As an example, members of this committee from Kansas, Nebraska, and South Dakota annually screen germplasm in a Tri-state hard red winter wheat nursery for susceptibility to Fusarium head blight. Similar efforts for FHB and other diseases are underway throughout the entire region with members of this committee and local wheat improvement programs working closely together.
e. Studies of the Population Biology of Small Grains Pathogens.
By monitoring the population biology of the pathogens of economic importance to small grains, we can 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.
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.
As funding permits, researchers in individual states or regions (e.g. the Northern Great Plains) will conduct similar surveys on the pathogens of economic importance in their region (e.g. Pyrenophora, Septoria/Stagonospora). Isolate collections will be generated and analyzed using traditional (e.g. virulence screening) as well as molecular or biochemical techniques (e.g. AFLPs, isozymes).
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 and coordinated email discussions (e.g. USDA Cereal Disease Lab Rust Listserve). We propose to continue this high level of interaction within the NCERA184 and WERA97 (our western counterparts). Additionally, we regularly share sources of resistance, elite germplasm, and pathogen isolates. This exchanges supports a number of research and varietal improvement programs.
Expected Outcomes and Impacts:
- Outcome 1. 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.
- Outcome 2. 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.
- Outcome 3. Refine risk assessment models that can be used in disease management regimes to increase producer productivity and profitability while maintaining crop quality.
- Outcome 4. Identify germplasm and advanced breeding lines that are disease resistant, and use them in the development of commercial varieties with improved disease resistance.
- Outcome 5. 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 6. Publish joint research articles and extension bulletins on common diseases.
- Impact 1. 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.
- Impact 2. Disease resistant germplasm and advanced breeding lines will be identified that will be used in the development of commercial varieties with improved disease resistance.
- Impact 3. 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.
- Impact 4. 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.
- Impact 5. The overall impact of these activities will result in improved yields for small grain crops in the region. In turn, this will allow producers maintain profitability while growing the 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.
Project Participation:Include a completed Appendix E form
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, by email (e.g. listserves), at grower-meetings and through the publication of multi-state extension bulletins.
An email listserve of state specialists developed this spring (2007) greatly facilitated collaboration among states attempting to secure emergency Section 18 registration for Folicur for their state. Last year, specialists in multiple states were able to work together when it appeared that registration had hit a roadblock and successfully obtain registration for the product.
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. Individuals can access their state of interest on the map, examine the model output and read a state specific commentary about FHB, other relevant wheat diseases, weather conditions and the crop development stages. A pilot program initiated in 2006 to determine the utility of state specific comments was expanded to include all 24 states covered by the model for 2007. Michigan and North Dakota have added their agricultural weather stations to improve area coverage in the state. It is anticipated that other state weather networks will also be incorporated.
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).
There will be two officers for NCR-XXX. 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.
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