Duration: 04/01/2004 to 09/30/2007

Administrative Advisor(s):

NIFA Reps:

Non-Technical Summary

Statement of Issues and Justification

Need Indicated by Stakeholders: Karnal bunt (KB) threatens the economic well being of wheat producers and rural communities in the Southern Plains and the United States (US) grain industry. One hundred thirty-five thousand individuals are directly involved in the production of the crop, and a total economic value of $4.76 billion is generated each year for the 2.5 million individuals and 1,200 rural communities located in this geographic region. On March 7, 2003, a Karnal Bunt Advisory Board met in Oklahoma City with scientists who comprised the executive committee of the NC503 fast-tract project titled Host Plant Control, Resistance to, and Best Management Practices for Karnal Bunt in Wheat. The Advisory Board members represent US wheat production, breeding, handling, merchandising, and research communities. They adopted a charter and elected David Worrall of AgriPro Wheat as their chair. The NC503 executive committee and the Advisory Board identified and prioritized research and Extension objectives that they believed would support efforts toward deregulation and help reduce economic risks associated with KB outlined below. Additionally, a Karnal Bunt Biosecurity Task Force comprised of stakeholders representing the Kansas Farm Bureau, Kansas Wheat Commission, Kansas Association of Wheat Growers, Kansas Department of Agriculture, and Kansas Crop Improvement Association, and representatives from the US Custom Harvesters Association, grain elevator industry, USDA, Kansas State University, Oklahoma State University, and Texas A&M identified the importance of expanding KB research and Extension activities. This task force agrees with the research and Extension objectives outlined by the Karnal Bunt Advisory Board and NC503 executive committee and strongly supports the formation of a North Central Region project to address Managing Karnal Bunt of Wheat. The National Association of Wheat Growers and the National Wheat Improvement Committee also recognized the importance of a specific research and extension focus on KB and adopted resolutions calling for increased research on KB in 2001. Importance and Consequences if not done: Kansas, Oklahoma, Eastern Colorado, the Texas Panhandle, and North Central Texas make up the geographic region known as the Southern Plains. Each year, over 26 million acres of hard red wheat are planted in this region, making it by far the most widely planted crop. Much of the wheat production in the Southern Plains is unique in that close to half of the crop is grown as winter forage for cattle in an addition to grain production. Each year, approximately ten million acres of dual-purpose wheat are cultivated on 23,000 farms, and six million cattle are grazed on wheat pastures. The value of grain produced on this acreage approaches two billion dollars, with an additional $256 million in value-added by grazing stocker cattle. Karnal bunt now threatens the economic sustainability of this wheat-based agricultural production system. In 1996, KB was found on durum wheat in Arizona, and it was soon discovered that infested seed also had been shipped to California, New Mexico, and Texas (Ykema et. al., 1996). Following its discovery in the southwestern US in 1996, the United States Department of Agricultures (USDA) Animal and Plant Health Inspection Service (APHIS) quarantined KB infected areas in an attempt to first eradicate the disease, and more recently, to contain its spread. By imposing severe quarantine measures on the movement and processing of wheat from infested areas, APHIS staff believed the disease could be eradicated. Specific quarantine measures included a restriction on interstate movement of grain, milling products and by-products, and grain harvesting and shipping equipment (Beattie and Biggerstaff, 1999). The quarantine failed to prevent the spread of the pathogen and increased concerns among other countries as to the real threat of the disease (Babadoost, 2000). Following the APHIS quarantine of wheat production areas in the Southwestern US in 1996, additional countries imposed quarantines on KB and now there are over 45 countries with import restrictions. In response to the 2001 outbreak of KB in north central Texas, USDA-APHIS held public hearings to build an industry consensus behind a strategy that would preserve the US wheat export market while minimizing economic hardship for producers and grain handlers in and surrounding quarantine areas. Participants were unanimous in their opinion that USDA must undertake the challenge of overcoming the classification of KB as a quarantine pest (deregulation) while preserving wheat export markets. As an outcome of this approach, APHIS developed a Karnal Bunt Strategic Plan for Deregulation While Preserving Export Markets. The APHIS plan calls for complete deregulation of KB as a quarantine pest by 2007 while negotiating with foreign trading partners to drop their quarantines. Deregulation of KB is a common goal, but the disease is an immediate concern to farmers and the US wheat industry due to its quarantine status and potential impact on exports. Tilletia indica is now established in several fields in Arizona, central Texas, and north Texas, and affected growers, seedsmen, and grain handlers have already experienced increased costs and loss of markets. The eventual spread of KB north into the main wheat growing regions of the Southern Plains seems probable, but whether this will occur before KB is deregulated is a matter of conjecture. The USDAs Economic Research Service (ERS) performed an Economic Analysis of Ending the Issuance of Karnal Bunt Phytosanitary Wheat Export Certificates. Vocke et al. (2002) reported the cumulative reduction of net farm income associated with an immediate unilateral deregulation of KB would approach $5.3 billion from 2003 to 2007. The ERS study assumes a class specific response to the termination of certificates for KB, resulting in premiums for hard red spring (HRS) wheat (grown in a KB-free production region) and discounts for hard red winter (HRW) and soft red winter (SRW) wheat grown in contaminated areas. The total impact of deregulation would be 45 cents per bushel average drop in farm price for wheat. Alternative market scenarios following the termination of certificates for KB (if accomplished), spread of KB throughout the Southern Plains, and the impact of developing resistant cultivars have not been analyzed. Great concern exists within the US wheat industry that KB will be used as a non-tariff trade barrier. Wheat producers throughout the Southwestern United States face significant financial losses if Karnal bunt is found on or near their farm. These losses can be minimized if acceptable alternative crops or cropping systems can be identified to replace wheat for grain in these Karnal bunt infested areas. Because the disease is so new to the United States and restricted to only a few locations, an integrated comprehensive disease management program has not been developed. A need exists to investigate alternative crops and cropping systems and the economies of implementing these systems if Karnal bunt becomes more wide spread. Any alternative crop or management recommendations will be made from an economical standpoint, and the long-term impact of KB on land values must be investigated. Because there are relatively large geographic areas in Texas where KB has occurred, it is one of the few places in the US where epidemiological and disease management studies can be conducted under natural field conditions. Farmers in areas where KB has been detected believe they have little choice but to plant wheat and hope the disease doesnt reoccur. From an epidemiological point of view, this action is risky. Each year, custom wheat harvesters begin cutting in Texas and move north. This happened in 2001 and combines unknowingly went from fields with KB to previously uninfested fields. Spread of KB teliospores north and northwest of quarantined areas in north central Texas either by equipment, cattle, infested seed, or wind, has probably occurred. However, our lack of knowledge concerning the primary components that impact incidence and severity of KB prevent any knowledgeable prediction of future disease outbreaks, either in the existing quarantined area or outside these areas. We do not know how teliospore inoculum that was deposited in the soil during harvest of past crops will impact disease development in future crops. We do not know how far spores were spread, how long they can survive, or how soil type or microclimatic conditions impact spore survival and future disease incidence. It is important that research be conducted that will improve our understanding of the ecology and epidemiology of this disease and provide producers with better management options and regulatory personnel with the data needed to deregulate KB. Resistant cultivars will be an important component of an integrated strategy to control KB. A wheat cultivar with a low level of resistance will produce fewer spores and bunted kernels after infection with Tilletia indica compared with a highly susceptible cultivar, thus there will be fewer spores available for subsequent infections. The adoption of highly resistant cultivars in and around areas where KB occurs will greatly reduce disease spreading into other areas. Genetic variability for KB resistance does exist and low levels of resistance have been found in some US winter wheat cultivars, however, most cultivars are highly susceptible. The capacity for US wheat breeders to screen for resistance in the US is limited by quarantine regulations. Therefore, the development of resistant germplasm, and eventually resistant winter wheat cultivars, will depend on cooperation with international partners such as the International Maize and Wheat Improvement Center (CIMMYT). CIMMYT is one of 16 International Agricultural Research Centers (IARC) funded by the Consultative Group for International Agricultural Research (CGIAR). CIMMYT scientists will provide some of the worlds best sources of KB resistance to this project. KB resistance screening is very difficult because: 1) it is very labor intensive since individual tillers are hand-inoculated, 2) screening results are highly variable, so multiple years of testing are needed for reliable results. At least for now, quarantines prohibit field screening in the US. The development and application of molecular markers is necessary to overcome this bottle neck in the breeding process without having to evaluate large populations for resistance in Mexico. Robust molecular markers will enable breeders to identify segregates with resistance to KB. These materials will then be tested in Mexico in cooperation with CIMMYT to confirm KB resistance. In order to maximize the impact of KB management recommendations, it is critical that the information be collected and organized in a compatible and understandable format. This will not only increase the publics awareness of the disease but will also reduce misinformation surrounding this disease. As new research findings become available, this information must be communicated to stakeholders in a timely and efficient manner using the land grant university Extension network. Technical Feasibility of the Research The problems with detecting T. indica and the fact that its occurrence may not result in significant yield losses complicate disease management options (Singh, 1994; Warham, 1986). Seed treatment fungicides are typically ineffective in reducing disease. Seed treatments can kill spores contaminating seed, but are usually ineffective against spores protected by the pericarp in partially bunted seed. Seed treatments are only recommended for use when planting potentially infested seed into non-infested soils. Foliar fungicides can be highly effective in the control of KB, but issues of environmental impact and expense become paramount. For instance, a single application of the fungicide Tilt on 10% of the wheat acres in the Southern Plains equates to 89,000 gallons of pesticide and a cost of approximately $39 million. Crop rotations, soil amendment, and tillage practices exert minimal impact on disease incidence (Singh, 1994). In view of these constraints, we propose the following research and Extension strategy for managing KB in wheat that is technically and economically feasible. Further research is needed to define planting date modification to avoid environmental conditions conducive to disease development. Research that defines KB epidemiology and ecology of T. indica Mitra teliospore viability in soil and climatic conditions that exist in the Southern Plains will enable the development of a field specific KB risk assessment model. The work conducted in this phase of the project will augment scientists efforts to develop alternative cropping strategies. Genetic resistance is currently available against KB, but it is primarily in spring wheat lines, and wheat produced in the Southern Plains is hard red winter wheat. CIMMYT has successfully incorporated KB resistance into high yielding spring wheat germplasm, and has indicated a willingness to assist North American breeding programs to transfer KB resistance into adapted winter wheat germplasm and cooperate on additional research initiatives important for US conditions. Marker assisted selection has been successfully employed in wheat lines for Fusarium head scab resistance. Using this technique, geneticists have been able to move quantitative resistance into wheat populations. Current work is underway to employ this technique in developing resistance to KB in wheat germplasm, though development of commercial available cultivars is forthcoming. Advantages of a Multi-State Effort: The threat of KB spread throughout the Southern Plains and devastating economic consequences to the US wheat industry requires a multi-state approach. This disease differs from other wheat diseases in that most US export customers have implemented quarantines that prevent shipment of KB contaminated wheat. In the absence of an aggressive multi-state reach and Extension approach, the economic consequences experienced by producers in quarantined production areas will extend throughout the Southern Plains following deregulation. The large economic and trade implications associated with this disease relative to infected acres and yield loss require a focused effort, however, no single university can presently justify dedicating the necessary resources to perform all the tasks outlined in this project. Additionally, the expertise to perform each of these tasks resides in multiple institutions located across the US. The conception of an enhanced Karnal bunt program grew out of discussions at five meetings since June 2001. Plant pathology department heads attending the North Central Division of the American Phytopathological Society meeting in Manhattan, KS discussed the issues on June 20, 2001. On August 2, 2001 the North Central Region Experiment Station directors approved a rapid response committee (NC503) to coordinate KB research and Extension programs (http://www.oznet.ksu.edu/nc503). On August 10, 2001, a Symposium on Karnal bunt was conducted at the Fall Cereal Conference, a regional winter wheat meeting, in Manhattan, KS. Stakeholders and researchers from several states participated, in addition to Dr. Guillermo Fuentes from CIMMYT. On August 27, there was an informal Karnal Bunt discussion at the annual meeting of the American Phytopathological Society in Salt Lake City. Approximately 60 participants from various agencies shared their experiences and opinions and endorsed a strengthened KB research program. On Oct. 31-Nov.1, 2001, USDA-APHIS hosted a workshop on KB in Oklahoma City. A consensus emerged that more research and Extension education activities were needed. On Jan. 16, 2002, NC503 met in Orlando, Florida, in conjunction with the National Association of Wheat Growers and the National Wheat Improvement Committee. Members of NC503 and representatives from several wheat commodity organizations traveled to Mexico April 1-5, 2002, and reviewed CIMMYTs Karnal Bunt research program. The group traveled to CIMMYTs research facility at Obregon and met with several researchers who gave a tour of research plots and facilities. CIMMYT and NC503 members had discussions to identify areas of mutual interest and to determine how researchers from Mexico and the US could best collaborate. The NC503 executive steering committee met in Stillwater, Oklahoma, on September 27, 2002. Discussions centered on research needs and priorities and identification of individuals to serve on a KB Advisory Board. Currently, faculty from multiple state experiment stations and USDA scientists are working collaboratively on managing Karnal bunt in wheat. The synergy and efficient utilization of resources from this collaborative effort should continue, as well as a desire to move forward under a Cooperative States Research, Extension, and Education Service (CSREES) regional project. The selection of the North Central Region as the administering entity is two-fold: first, the administrative advisory for the project, Forrest Chumley, possesses expertise as a molecular plant pathologist and directs the Kansas Experiment Station, and, second, the Plant Pathology Division head of the US Grain Marketing and Production Research Center, Robert Bowden, administers the USDA budget that currently provides some funding to the existing multi-state effort. Likely Impacts and Outcomes: 7 Scientists will better define the epidemiology and ecology of T. indica for use in predicting KB spread. 7 Creation of a real-time, web-based, field specific KB risk assessment model will augment efforts to manage KB in wheat and minimize spread. 7 Through the use of marker-assisted selection, geneticists will be able to move quantitative KB resistance into wheat populations. 7 New commercial wheat cultivars possessing KB resistance will minimize spread and may lead to the eradication of this disease in the Southern Plains. 7 Alternative cropping strategies will be introduced into quarantine areas to preserve the economic viability of these agricultural communities until deregulation occurs. 7 The formulation and analysis of marketing strategies to manage Karnal bunt and retain global wheat markets will address multiple scenarios and lead to improved cost and benefit analysis of policy decisions, ultimately facilitating deregulation of KB as a quarantine pest. 7 Producers in and around KB quarantined areas will implement new management strategies that minimize spread of this disease prior to the commercial availability of resistance cultivars, thus ameliorating the economic burden imposed by the quarantine. 7 These combined efforts will enable deregulation of KB as a quarantine pest while retaining global export markets.

Related, Current and Previous Work

Karnal bunt (KB), caused by the fungal pathogen Tilletia indica Mitra, is a disease of bread wheat (Triticum aestivum), durum wheat (T. durum), and triticale (wheat x rye x triticosecale) (Sansford, 1998). The disease was first identified in the Karnal district of Northern India in 1931. The disease quickly spread throughout northern and central India and is now common in several other Asian and Mid-Eastern countries, including Pakistan, Afghanistan, Nepal, Iran, and Iraq. The pathogen was not identified outside of Asia until 1972 when it was reported from the state of Sonora in Northern Mexico (Sansford, 1998). At that time, the disease seemed to be restricted to the Yaqui and Mayo Valleys in Sonora, and was found in only trace amounts in farmers fields. However, in the early 1980s, disease surveys in these valleys found that up to 64% of the farms tested positive for KB. At that point, the Mexican government imposed actions to contain the disease by restricting movement of seed within the country (Sansford, 1998). In response, the USDA Animal and Plant Health Inspection Service (USDA-APHIS) designated T. indica as a controlled pathogen and in 1982 imposed a zero tolerance quarantine on the import of all wheat seed from Mexico (Beattie and Biggerstaff, 1999; Poe, 1998; Warham, 1986). This action was based primarily on political and economic concerns, and was taken without first acquiring scientific data that supported the ruling (Fuentes-Davila, 1998). Although only four countries had quarantine restrictions on KB before 1982, the number soon increased to 22 following the U.S. action (Beattie and Biggerstaff, 1999). T. indica seldom causes significant yield losses. Teliospores of T. indica are the survival propagules for this fungus. It survives in the soil, and when exposed to cool, wet conditions, the spore germinates to give rise to primary sporidia (Dhiman, et al., 1984; Holmes, et al., 1996; Smilanick, et al., 1985). Primary sporidia are moved from the teliospore, either from forcible ejection, rain splash, or air currents, to the leaf surface of a host plant where they germinate and give rise to secondary sporidia. These secondary sporidia germinate and penetrate a wheat floret through stomata. Wheat plants are primarily susceptible to infection from early boot stage to anthesis; however, several reports indicate that infection is most successful while the head is still in the boot (Kumar and Nagarajan, 1998; Aujla, et al., 1982; Royer and Rytter, 1985; Warham, 1990a). As the pathogen infects the immature wheat seed, hyphae infect the pericarp and form a compact layer of mycelium that eventually gives rise to teliospores. Growth of the mycelium inside the pericarp eventually ruptures the connection between the pericarp and surrounding vascular bundles, and as a result, the seed atrophies to varying degrees. Partial bunting is common but, in the most extreme cases, the entire seed becomes shriveled and the embryo dies (Cashion and Luttrell, 1988; Goates, 1988; Fuentes-Davila and Duran, 1986; Roberson and Luttrell, 1987). In most cases, only a few kernels in each spike become infected (Royer and Rytter, 1986). There is a significant difference in susceptibility among wheat cultivars and some are highly susceptible, resulting in a significantly greater percentage of infected kernels per spike. There have also been reports that individual isolates of T. indica are more virulent than others. However, variability among isolates has not been adequate to justify designation of races (Beck, et al., 1994; Bonde, et al., 1996; Datta, et al., 2000; Pimentel, et al., 1998). T. indica infected plants can experience reduced seed viability, germination and vigor (Bansal, et al., 1984; Singh, et al., 1983; Warham, 1990b). Bunted grain negatively impacts seed quality by imparting an off color (Sekhon, et al., 1981; Sekhon, et al., 1992). The low disease incidence, typical of most fields with KB, results in no toxicological issues (Bhat, et al., 1983; Singh, et al., 1992). The low KB incidence in infected fields greatly complicates detection of the pathogen in field soil or grain samples at harvest. Consequently, few attempts to quantify KB distribution in diseased wheat heads in the field or teliospores in the soil have been performed (Sawyer, et al. 1997a; Sawyer, et al., 1997b). A need exists to develop and test sampling strategies that will obtain an accurate estimation of diseased heads or teliospores in soil or grain samples. Methods devised to isolate T. indica spores from the soil involve washing, sieving, centrifugation, and, in some methods, density gradient centrifugation, resulting in significant cost and time to perform (Babadoost and Mathre, 1998; Datnoff, et al., 1988). Teliospores detection in contaminated grain is slightly less tedious than soil samples (Agarwal and Verma, 1983; and Singh, 1981). The final confirmation of teliospore identity and number relies upon microscopic observation. A need exists to develop methods to detect the pathogen in infected plant tissue before harvest or teliospore formation. This would alleviate the logistical problems in regulated areas when custom grain harvesters must wait for APHIS as to confirm the presence or absence of KB in a suspect field. To date, no integrated comprehensive disease management program has been developed. Crop rotations, soil amendment, and tillage practices have had minimal impact on disease incidence (Singh, 1994). Planting date can be modified to avoid periods of weather that are conducive for disease, but these conditions are not well established and this strategy is ineffective for winter wheat. Genetic resistance is currently available against KB, but it is primarily in spring wheat lines, and wheat produced in the Southern Great Plains wheat production region is hard red winter wheat. Although existing breeding lines with high levels of resistance to KB are available, programs to introduce this resistance into winter wheat lines have just recently been established in the U.S. (Rajaram and Fuentes-Davila, 1998). The valuable genetic diversity of CIMMYT germplasm has largely gone untapped by US wheat breeding programs due to quarantine restrictions that have been in place for the last 20 years. CIMMYT has a wealth of resistance germplasm for KB and other diseases that will benefit U.S. wheat production. Some of the traits that CIMMYT is actively working on include: drought tolerance, heat tolerance, durable leaf rust resistance, new sources of leaf, stem, and stripe rust resistance, good head scab resistance and many others. CIMMYT is already working on the next generation of germplasm that will move yield levels to a new plateau. Derivatives from synthetics and crosses to yield component materials are showing significant promise for increased biomass production and yield levels. Dr. Art Klatt has introduced more than 3500 lines from CIMMYT during the last 4 years. These lines have been cleared through quarantine regulations and will undergo screening for agronomic type and leaf rust resistance. A need exists to expand this collaborative KB research program to insure availability and facilitate access to CIMMYT germplasm. Seed treatment fungicides are typically ineffective in reducing disease. Seed treatments can kill spores contaminating seed, but are usually ineffective against spores protected by the pericarp in partially bunted seed. Seed treatments are only recommended for use when planting potentially infested seed into non-infested soils. Foliar fungicides can be highly effective in the control of KB, but issues of environmental impact and expense become paramount. Fungicide applications for the control of KB rely upon proper time (Singh, et al., 1993; Smilanick et al., 1987), however, current fungicide scheduling programs rely solely on plant morphology. At present, there are no adequate weather-based disease-forecasting programs that support timely applications. Although a variety of KB disease models have been developed, most are regionally specific (Sansford, 1998) and not suited to the environmental conditions typical for the Southern Great Plains wheat-growing region. The Sequeira (2001) model only has resolution at the county level. The quarantined counties in north central Texas are approximately 900 square miles in size, and therefore, a model with only county resolution is inadequate for helping individual producers make timely management decisions. A need exists to develop a KB risk-assessment model that will enable more informed management decisions. The USDAs Economic Research Service (ERS) performed an Economic Analysis of Ending the Issuance of Karnal Bunt Phytosanitary Wheat Export Certificates. Vocke et al. (2002) reported the cumulative reduction of net farm income associated with an immediate unilateral deregulation of KB would approach $5.3 billion from 2003 to 2007. As a first step in the analysis, export customers were categorized based on their likelihood of purchasing US wheat following deregulation. Approximately 25 percent of US export customers possess strict phytosanitary requirements and would adhere to restrictions that imported wheat come from Karnal bunt-free production regions. ERS estimates that 35 percent of US export customers would adhere to their restriction for two years before relaxing KB standards to tolerance levels that would permit trade. The remaining 40 percent would not limit trade of US wheat in the face of complete deregulation according to the ERS economic analysis. The ERS study assumes a class specific response to the termination of certificates for KB, resulting in premiums for HRS (grown in a KB-free production region) and discounts for HRW and SRW grown in contaminated areas. The total impact of deregulation would be 45 cents per bushel average drop in farm price for wheat. The ERS study also assumes that major competitors in the global wheat market would increase production by 15 million tons. The economic analysis was performed using the Food and Agricultural Policy simulator (FAPSIM). Alternative market scenarios following the termination of certificates for KB were not analyzed, nor were wheat exporters involved in assessing market strategies they would pursue in response to KB deregulation. Several possible alternative scenarios, posed as questions, include:

• Would HRW producers in KB-free production regions such as Kansas, Colorado, Nebraska, and South Dakota, ship wheat to the Pacific Northwest, via rail, for export?
• If this alternative transportation route were used, how would rail rates change?
• Would HRS shippers utilize different transportation routes following the termination of certificates for KB and is there an additional cost?
• What, if any, documentation would US export customers demand for KB free wheat after APHIS discontinues their annual elevator survey and no longer issues certificates?
• What would this documentation system cost and will it vary by country or customer?
• Would the grain industry require new risk management tools following deregulation and how much would these tools cost?

In view of economic uncertainties surrounding KB deregulation, a need exists to identify and evaluate marketing scenarios and risk management strategies that meet exporting country/customer concerns and retain the comparative advantage of the US wheat industry in the global market.

Objectives

1. Define Karnal bunt (KB) ecology and epidemiology to enable global deregulation of KB and minimize pathogen spread
   
2. Develop high yielding KB resistant germplasm adapted for the Great Plains region in cooperation with CIMMYT
   
3. Develop new molecular markers for KB resistance genes to assist breeding program.
   
4. Evaluate alternative crops and cattle grazing management systems and develop economic decision aids to minimize the impact of KB
   
5. Evaluate strategies to retain global wheat markets that meet export customer KB phytosanitary regulations
   
6. 
   

Methods

Objective 1: Define Karnal bunt (KB) ecology and epidemiology to enable global deregulation of KB and minimize pathogen spread by: I. Evaluating teliospore distribution and viability from KB infected wheat fields in Texas. Although it is known that KB typically occurs at low incidences in infected crops, the longevity of the spore load that is deposited following a diseased crop and the distribution of the spores is unknown. Scientific data of this type is required as a prerequisite for deregulation. Several fields that tested positive for KB in 2001 or 2002 will be grid soil sampled. Fields will be divided into one-acre quadrats (large), and soil will be sampled from 10 randomly selected locations in each quadrat and composited. In addition, 4 quadrats from each field will be randomly selected and further divided into 4m x 7m quadrats (small). Teliospores will be extracted from each soil sample, tested for viability, and quantified as described (Babadoost and Mathre, 1998; Datnoff et al., 1988). Teliospore data will then be subjected to geostatistical analysis for determination of their spatial distribution. Unsampled locations will be estimated using block kriging, and spatial patterns of teliospores in the field will then be mapped, compared, and interpreted (Rossi, et al., 1992). II. Examining teliospore survival in soils from various US wheat growing regions. The association of specific soil types with teliospore viability and survival could lead to development of a soil profile map that identifies specific soils as conducive or antagonistic to T. indica. Multiple representative soil samples from the Southern Great Plains will be obtained from collaborators. Aliquots of the samples will be spiked with teliospores of T. indica and sealed in spore-proof polyester bags. Bags containing teliospore-spiked soil will be placed into a) glass jars and b) polyvinyl chloride (PVC) tubing, modified to be spore-proof while still allowing water pass-through. Both vessels will also contain teliospore-free soil from the original sample. Pre-determined amounts of water will be added to soil in the glass jars to obtain multiple soil-moisture treatments. The jars will be incubated in the quarantine laboratory in Bushland, TX, and spore-proof PVC tubes will be buried in KB quarantined (already positive) fields in the regulated counties in north central Texas. After one year, the PVC tubes will be returned to the quarantine laboratory and bags containing teliospore-spiked soil will be removed from both the jars and PVC tubes. Teliospores from the spiked-samples will be extracted. Teliospore recovery will be assessed microscopically and teliospore viability will be determined by the percentage germinated after 11 days on water agar. During the one-year incubation period, the teliospore-free soil samples will be processed for soil structure and chemistry, and biological community structure using standard techniques (Ibekwe, A.M., et al., 2001). Correlations between soil composition, chemistry, and/or biological activity with teliospore viability will be conducted. III. Developing improved methods for detection and quantification of T. indica in soil and infected plant tissues. Numerous immunochemical and molecular-based techniques have been developed to detect and differentiate between T. indica and other smut fungi (Beckman, et al., 1994; Bonde, et al., 1996; Frederick, et al., 2000; Kutilek, et al., 2001; Levy, et al., 2001; Luster, et al., 1998; McDonald, et al., 1999, 2000; Smith, et al., 1996)). However, all published techniques to date have been developed for diagnostic purposes, and most have used germinated teliospores. It is unknown whether any of these are capable of detecting the pathogen in soils or in planta. We will test and compare existing techniques for efficacy in detecting T. indica in infected wheat spikes and immature kernels before teliospore formation. Because of its specificity, real-time PCR will be the preferred technique. If existing procedures that are based on germinated teliospores do not work, we will manipulate reaction parameters and evaluate various primer combinations based on known sequence data (Fredrick, et. al. 2000) until we develop a real-time PCR protocol that works with infected plant tissue and field soils. Wheat plants in early to mid-boot (Feekes scale 9 - 10) will be inoculated with sporidia of T. indica by injecting a spore suspension of approximately 10,000 sporidia/ml directly into the boot with a hypodermic needle (Royer and Rytter, 1985, 1986; Warham, 1990). Inoculated plants then will be incubated in growth chambers maintained at 22oC and near 100% relative humidity to maximize infection, as previously described (Royer and Rytter, 1986; Bonde, et al., 1999; Warham, 1990a). Three days after inoculation, five spikes will be harvested and fungal DNA will be extracted and used as a template in real-time PCR reactions (Vandemark, et al., 2000; Winton, et al., 2002). This procedure will be repeated every seven days for approximately 28 days; the time at which mature teliospores should began to appear (Cashion and Luttrell, 1988; Fuentes-Davila and Duran, 1986). Primer pairs that are able to amplify fungal DNA directly from infected spikes will be optimized for assay performance and the best primers for early detection will be determined by comparing output data generated by analysis software. IV. Developing a real-time, web-based, field specific KB risk assessment model. The goal of this objective is to develop a model that would allow a grower to log on to our KB web site, enter the latitude and longitude for his specific field and receive a weather-based risk assessment that predicted the likelihood for KB. Such a field-specific risk assessment model would provide producers with rapid, accurate information needed to make more informed management decisions. A prototype has been developed for sorghum ergot in hybrid seed production fields. Use of Doppler radar in development of such a model is unique and would provide a much higher resolution of conducive environmental conditions than any existing KB model. It would greatly increase the likelihood that fungicide applications would be applied at the appropriate time and only when needed. An accurate risk assessment model would also give producers time to consider other management options such as graze out or harvest for hay. The development of a site-specific prediction system involves integrating Geographical Information System (GIS) data, remote sensing data, and computational sciences to provide timely information (daily or weekly). Daily weather data, such as air temperature, relative humidity, wind velocity, etc., will be obtained from the National Weather Service (NWS) and Federal Aviation Administration (FAA). These weather data from point data sources will be ingested through a GIS system and interpolated using kriging techniques to produce a continuous surface of weather data. Daily precipitation data will be obtained from the NEXRAD system of NWS. NEXRAD is a Doppler radar known as the Weather Surveillance Radar-1988 Doppler (WSR-88D). NEXRAD provides precipitation data for larger areas, and with better spatial (4km x 4km) and temporal resolution (hourly), than conventional rain gauges. Localized precipitation events are very common in Texas, which is characteristic of arid and semi-arid climatic conditions. These precipitation events may not be captured by the sparsely located rain gauges. As Karnal bunt favors cool and wet weather conditions, spatially distributed precipitation data will help identify the effect of localized precipitation events on the spread of disease. A statistical model will be developed by correlating historical weather data with the occurrences of Karnal bunt in 1997 and 2001 in Texas. This statistical model will then be used as a prediction tool to give probability of disease occurrence based on field specific weather conditions. The weather information related to Karnal bunt and the disease prediction will be distributed to stakeholders and farmers through the World Wide Web (WWW) using ArcIMS. ArcIMS, which is an internet-based mapping system that combines the traditional GIS system with the internet, will allow the user to display, query, and analyze information using a Web browser. Using this system, the user will be able to query site-specific weather information and the probability of disease by providing the latitude and longitude of a specific field. Objective 2: Develop high yielding KB resistant germplasm adapted for the Southern Plains region in cooperation with CIMMYT by: I. Screening hard winter wheat cultivars and breeding lines commonly grown in the Southern Plains for resistance to KB. Screening will be done in cooperation with CIMMYT in the Yaqui Valley. Initially, priority will be given to materials from Texas, Oklahoma, Kansas, Colorado, and Nebraska because of the potential threat of KB spreading to these states. Dr. Art Klatt assembled approximately 400 entries for the 1st KB Screening Nursery and forwarded them to CIMMYT in October 2002. Dr. Guillermo Fuentes, CIMMYT Wheat Pathologist, will be responsible for the inoculation and evaluation process in Mexico. In subsequent years this screening program will be expanded to include winter wheat materials from other regions in the US, plus materials derived from the KB germplasm development efforts of this project. It is anticipated that by year 3 of this project, more than 1000 lines annually will be screened jointly with CIMMYT. II. Expanding backcross program to transfer KB resistance genes from spring wheat sources into winter wheat. A limited crossing program has been initiated to transfer KB resistance from spring wheat lines to adapted winter wheat materials using cultivars and advanced breeding lines from Kansas, Texas, Oklahoma, and Colorado. The single cross seed was sent to the respective programs, and each program is responsible for making backcrosses or three-way crosses. A limited number of new single crosses will be made at OSU in response to the identification of new sources of resistance. Kansas State University (KSU) has made a limited number of crosses to KB resistant sources from India. Texas A&M University (TAMU) has advanced lines derived from crosses to synthetics that may have KB resistance. These lines are currently being evaluated. Crossing emphasis will shift to winter wheat sources of KB resistance when these sources are identified. Dr. Art Klatt has introduced more than 3500 lines from CIMMYT during the last 4 years. These materials have been cleared through quarantine regulations and will undergo screening for agronomic type and leaf rust resistance. Promising materials will be incorporated into the crossing program at OSU. Populations (F2 and F3) derived from crosses to these introduced materials will be evaluated in Oklahoma, Texas, Kansas, and Colorado. On a limited basis, promising introductions will be shared with interested breeding programs, contingent upon APHIS approval as per quarantine regulations. As breeders identify promising lines for their individual target areas, they will be submitted to CIMMYT for KB screening in order to identify the next generation of KB resistant parents. III. Developing mapping populations to facilitate marker assisted selection (MAS) techniques. CIMMYT personnel agree to make crosses between 4 of the best sources of KB resistance and susceptible spring wheat lines. The crosses will be used to develop mapping populations. Dr. Maarten Van Ginkel, Head of the Bread Wheat Program, and Dr. Mujeeb Kazi, Head of the Wide Cross Program, will be the principle cooperators at CIMMYT, and Dr. Robert L. Bowden and Dr. G.L. Brown-Guedira (USDA-ARS Manhattan, KS) and Dr. Allan Fritz and Dr. B.S. Gill (KSU) will be the primary cooperators in the US The development of suitable markers associated with the KB resistance genes will greatly facilitate the development of KB resistant germplasm. As new sources of resistance are identified, additional marker studies will be required. Objective 3: Develop new molecular markers for KB resistance genes to assist breeding program. We will develop molecular markers for resistance genes from several sources of KB resistance. Mapping populations for CIMMYT sources of resistance are being developed and mapping populations for several Indian sources of KB resistance are already available and have already been field tested. Here are the Indian mapping populations for which we have field screening data: HD29 (resistant) x WL711 (susceptible) HD29 (resistant) x WH542 (susceptible W485 (resistant) x WH542 (susceptible) The Indian line HD29 has consistently been rated highly resistant in both Indian and Mexican KB screening tests. The first mapping population (HD29/WL711) was created by crossing HD29 with WL711, a highly susceptible line, at Punjab Agricultural University by Dr. Indu Sharma. One hundred and thirty recombinant inbred lines (RILs) have been evaluated for reaction to KB in India for four years. These lines and the screening data were provided to researchers from Kansas State University and USDA-ARS for marker development. A framework map consisting of >200 simple sequence repeat (SSR) loci was created and a QTL (~30% of variation due to genotype) for KB resistance was discovered on chromosome 4BL. This QTL was validated in an independent doubled haploid mapping population that was created and evaluated at CIMMYT. We will target that region of chromosome 4BL with SSR and EST markers to identify more closely linked markers flanking the resistance QTL. Preliminary analysis of the HD29/WH542 population found a second QTL on chromosome 6B. A second source of resistance is being mapped with 109 RILs from the cross W485/WH542. W485 has high resistance similar to HD29. A cross of W485 and HD29 showed transgressive segregation for even higher resistance. Therefore, the genes in the two lines are not identical. Confirmation of resistance in lines developed by MAS will be done by including lines in screening nurseries in India and Mexico. Also, inoculations in growth chambers will be done on a limited basis. Objective 4: Evaluate alternative crops and cattle grazing management systems and develop economic decision aids to minimize the impact of KB by: I. Comparing sorghum forages for their yield and nutritional value under dryland, limited, and full irrigation. Adaptability of forage sorghum hybrids to the Southern Great Plains region will be evaluated by conducting variety trials of forage sorghums and sorghum x sudan crosses. Entries will include brown midrib (BMR) and photoperiod sensitive hybrids. Yield as well as nutritional characteristics will be evaluated. Grazing studies will also be conducted to evaluate the potential of the BMR sorghum hybrids for increased cattle weight gain compared to conventional non-BMR sorghum hybrids. II. Examining the potential of small grains such as barley, oats, rye, and canola in various cattle grazing and grain production systems to replace dual-purpose wheat. Small grain alternatives to the dual-purpose wheat system will be evaluated by conducting small grain forage and grain trials. Multiple varieties of oats, rye, barley, and canola will be evaluated for forage (fall, spring, and entire season yields) and grain yields and will be compared to wheat and triticale. The crop development and adaptability to these environments, including forage regrowth, forage quality, and livestock performance will be recorded. Studies will include both small plot and grazing trials. III. Evaluating the yield and nutritional value of wheat, triticale, oats, and rye, harvested at various stages of maturity, for hay and silage. Harvesting wheat or triticale for hay and silage production, prior to the soft dough stage of development, is a possible alternative to wheat grain production. Varieties of wheat and triticale will be tested to determine their suitability for silage and hay production in the Southern Plains. Varieties will be harvested at different stages to determine their yield and nutritional value. IV. Analyzing the economic impact of KB regulated areas and developing decision aids to minimize the impact of KB on wheat producers. Survey data will be collected from local producers and elevators to assess the costs associated with the Karnal bunt quarantine. These figures will be used to calculate the direct costs. The indirect costs will be calculated by using an economically accepted multiplier. The economic analyses for each pertinent research component will be conducted by using enterprise budgets and incorporating these into a whole farm situation. In this way, the impact of alternative crops and/or grazing can be evaluated for their impact on the producers livelihood. Objective 5: Evaluate strategies to retain global wheat markets that meet export customer KB phytosanitary regulations by: I. Identifying alternative marketing, transportation, and phytosanitary certification strategies in response to the following scenarios: a) deregulation of KB as a quarantine pest by the US; b) spread of KB into main US wheat production areas; and c) development of new KB-resistant varieties. Individuals and market institutions that are directly or indirectly affected by Karnal bunt deregulation include: seed producers, custom harvesters, US grain producers, warehouse regulators, grain inspection service, transportation industry, risk protection entities, legal representation, and finance and credit. Personal interviews and questionnaires will be employed in the process of identifying, documenting, and quantifying market institution issues and alternatives. In some cases (especially those where alternative solutions are evaluated), focus groups and selected panels representing particular market institutions will be used. We will involve stakeholders in the process of defining the points of control in the production and delivery of KB-free wheat. In this process, we will describe the operating practices at each critical point and draft standard operating practices (SOPs). Stakeholder involvement will include several regional workshops. These meeting are designed to attract grain industry leaders from different agricultural sectors and they will assist in prioritizing where the alternative markets action group should focus their research and outreach efforts. II Assessing the cost of alternative marketing strategies. We will perform several scenario analyses in a case study format, based on input from stakeholders. The additional steps associated with marketing wheat following deregulation will be documented, including those needed to prevent the spread of KB through equipment, livestock, seeds, and transportation equipment. Cost structure analysis for producing/marketing KB-free wheat will include a comparative analysis of wheat enterprises before and after deregulation. This approach will enable us to evaluate the cost of alternative marketing systems. We will create management and educational tools for identity preserved (IP) marketing of wheat destined for export. Producer adoption of a quality management system that minimizes the risk of KB spread must involve an education program delivered by multiple agricultural institutions including Extension, commercial grain handlers, producer associations (e.g., state wheat grower associations and Farm Bureau), agriculture lenders, and the USDA Farm Service Agency. Financial analysis of additional steps to prevent the spread of KB will be evaluated using capital budgeting and enterprise budgets. Capital budgeting will be used to evaluate whether it is feasible to invest in additional equipment and procedures to produce KB-free wheat, and enterprise budgets will be created to estimate the cost and revenue impacts of this strategy.

Measurement of Progress and Results

Outputs

• Scientific data concerning the ecology and epidemiology of T. indica,
• Real-time, web-based, field specific KB risk assessment model
• Best management practices and standard operating procedures that will enable producers to minimize the spread of KB
• Regionally adapted breeding lines with high levels of KB resistance and new wheat cultivars possessing KB resistance
• Economic analysis of various alternate crop management scenarios
• Long term marketing scenarios relating to KB deregulation. Distance learning program and Extension education material.

Outcomes or Projected Impacts

• Sustained economic viability of the U.S. wheat industry and rural communities in the Great Plains. This will occur as producers adopt best management practices including alternate cropping strategies in KB infected fields, use of a web-based epidemiological model that facilitates risk assessment, and new wheat cultivars with KB resistance, which will minimize the spread of KB.
• Wheat industry stakeholders including producers, grain handlers, merchandisers, processors, agriculture lenders, farm implement dealers, custom wheat harvesters, agency personnel including APHIS, and university employees will possess an increased knowledge of how to minimize the spread of KB and retain global wheat markets in response to the distance learning and Extension outreach component of this project.
• The U.S. wheat industry will successfully deregulate KB as a quarantine pest with minimal loss of revenue to the U.S. wheat industry in response to adopting technology and marketing strategy output of this project. These combined efforts will minimize the threat that export customers will use KB as a non-tariff trade barrier.
• Scientific advancements in defining quantitative resistance to KB and other diseases through marker assisted selection will enable breeders to boost wheat yield potential and improve the international competitiveness of the U.S. wheat industry.

Milestones

(2005): 25% of wheat industry stakeholders in CO, KS, OK and TX will utilize information developed in this project including the adoption best management practices, alternative cropping strategies, and standard operating procedures that minimize the threat of KB spread in the Southern Plains. Seed producers, custom harvesters, U.S. grain producers, warehouse regulators, grain inspection service, grain handlers, transportation industry, risk protection entities, legal representation, finance and credit will identify market risks associated with deregulating KB as a quarantine pest. Beta-testing of the epidemiological web-based model. Identification and incorporation of wheat lines possessing KB resistance in breeding programs in the Great Plains.

(2006): 40% of wheat industry stakeholders in CO, KS, OK and TX will utilize distance learning information developed in this project. Quantification of KB resistance in wheat using marker assisted selection. Preliminary selection of commercial wheat cultivars possessing KB resistance.

(2007): 55% of wheat industry stakeholders in CO, KS, OK and TX will utilize distance learning information developed in this project. Role-out of the epidemiological models for application in commercial wheat production. Wheat crosses made by breeders in Great Plains using marker assisted selection technology. Deregulation of KB as a quarantine pest, accompanied by adoption of alternative marketing and certification strategies to retain global wheat markets.

(2008): 70% of wheat industry stakeholders in CO, KS, OK and TX will utilize distance learning information developed in this project. Wheat selections with KB resistance are included in preliminary yield trials throughout the Plains States.

(0):0

Projected Participation

View Appendix E: Participation

Outreach Plan

Objective: Create and disseminate educational material including science-based performance standards on KB management, marketing strategies, and regulatory restrictions to wheat industry stakeholders by: I. Building a nationwide distance-learning program with accompanying training modules. Curriculum Development - Develop a curriculum (distance education modules, training materials, Extension publications, web pages) for managing KB in wheat including Best Management Practices (BMPs) and auditable Standard Operating Practices (SOPs) for producing, handling, and marketing wheat that minimize the risk of KB spread. Target Audience  The target audience for this curriculum will be individuals who derive a portion of their livelihood from wheat produced in the Southern Plains. These target learners include seed dealers; crop consultants; Extension educators and specialists; grain elevator owners, managers, and operations employees; grain merchandisers; feed manufacturers; custom harvesters; and equipment manufacturers and dealers. II. Preparing Extension publications and decision aids Extension publications and decision aids will be prepared based on a thorough review of the research and as new science based information is developed through research performed in this CSREES project. Economic analysis of management alternatives to minimize the spread of KB and retain global markets will be packaged in spreadsheet format using Excel. III. Developing web pages A project web-site that contains links to participating institutions Extension and research web sites. IV. Holding public meetings As new research information becomes available, research and Extension personnel will develop and disseminate this information to the public via county and regional field day presentations. V. Journal articles Contribute to the scientific body of knowledge on KB through referred journal articles.

Organization/Governance

This project will continue the organization and governance structure established for the NC503 project Host Plant Control, Resistance to, and Best Management Practices for Karnal Bunt in Wheat. This governance includes an executive steering committee comprised of an elected chair, vice-chair, secretary, and a representative for each project objective. An early goal of the executive committee was to recruit a diverse group of stakeholders who represented a broad spectrum of the U.S. wheat industry to serve in an Advisory Board capacity. An advisory board to this project was formed and met with the executive committee on March 7, 2003. The Advisory Board adopted a charter and elected David Worrall of AgriPro Wheat as its chair. The mission statement of the charter is as follows: It shall be the objective of the Advisory Board to provide counsel to and build support for Land Grant University scientists working on risk assessment, host plant control, resistance to, and best management practices for Karnal Bunt (KB) of wheat. The complete Advisory Board Charter can be found as an attachment.

Literature Cited

Agarwal, V. K. and H. S. Verma. 1983. A simple technique for the detection of Karnal bunt infection in wheat seed samples. Seed Research 11(1):100-102. Aujla, S. S., K. S. Gill, A. S. Grewal and I. Sharma. 1982. New technique of mist spray for Karnal bunt studies. Indian Phytopathology 35:716-717. Babadoost, M. 2000. Comments on the zero-tolerance quarantine of Karnal bunt of wheat. Plant Disease 84(7):711-712. Babadoost, M. and D. E. Mathre. 1998. A method for extraction and enumeration of teliospores of Tilletia indica, T. controversa, and T. barclayana in soil. Plant Disease 82(12):1357-1361. Bansal, R., D. V. Singh and L. M. Joshi. 1984. Effect of Karnal-bunt pathogen [Neovossia-indica (Mitra) Mundkur] on weight and viability of wheat seed. Indian Journal of Agricultural Sciences 54(8):663-666. Beattie, B. R. and D. R. Biggerstaff. 1999. Karnal bunt:A wimp of a disease - but an irresistible political opportunity. Choices: The Magazine of Food, Farm and Resources Issues. 14:4-8. Beck, R. J., O. P. Smith, P. W. Tooley, G. L. Peterson and M. R. Bonde. 1994. Characterization of double-stranded RNA from Tilletia indica. Mycologia 86(5):656-659. Beckman, K. B., J. G. Harrison and D. S. Ingram. 1994. Optimization of a polyclonal enzyme-linked immunosorbent assay (ELISA) of fungal biomass for use in studies of plant defense responses. Physiological and Molecular Plant Pathology 44:19-32. Bhat, R. V., B. Rao, D. N. Roy, M. Vijayaraghavan and P. G. Tulpule. 1983. Toxicological evaluation of Karnal bunt wheat. Journal of Food Safety 5(3):105-111. Bonde, M. R., S. E. Nester, A. Khayat, J. L. Smilanick, R. D. Frederick and N. W. Schaad. 1999. Comparison of effects of acidic electrolyzed water and NaOCl on Tilletia indica teliospore germination. Plant Disease 83(7):627-632. Bonde, M. R., G. L. Peterson, G. Fuentes-Davila, S. Aujla, G. S. Nanda and J. G. Phillips. 1996. Comparison of the virulence of isolates of Tilletia indica, causal agent of Karnal bunt of wheat, from India, Pakistan, and Mexico. Plant Disease 80(9):1071-1074. Bonde, M. R., G. L. Peterson, N. W. Schaad and J. L. Smilanick. 1997. Karnal bunt of wheat. Plant Disease 81(12):1370-1377. Cashion, N. L. and E. S. Luttrell. 1988. Host-parasite relationships in Karnal bunt of wheat. Phytopathology 78(1):75-84. Datnoff, L. E., M. H. Royer, M. R. Bonde and J. M. Prescott. 1988. A quantitative method for estimation of teliospores of Tilletia indica in soil. Plant Disease 72(3):209-212. Datta, R., M. D. Rajebhosale, H. S. Dhaliwal, H. Singh, P. K. Ranjekar and V. S. Gupta. 2000. Intraspecific genetic variability analysis of Neovossia indica causing Karnal bunt of wheat using repetitive elements. Theoretical and Applied Genetics 100(3-4):569-575. Dhiman, J. S., P. S. Bedi and H. S. Mavi. 1984. Relationship among temperature, humidity and incidence of Karnal bunt of wheat. Indian J. Ecol. 11(1):134-138. Frederick, R. D., K. E. Snyder, P. W. Tooley, Y. Berthier-Schaad, G. L. Peterson, M. R. Bonde, N. W. Schaad and D. A. Knorr. 2000. Identification and differentiation of Tilletia indica and T. walkeri using the polymerase chain reaction. Phytopathology 90(9):951-960. Fuentes-Davila, G. 1998. Karnal bunt of wheat. Pages 69-81. In: Proc. Bunts and Smuts of Wheat: An International Symposium. North Carolina. North American Plant Protection Organization, Ottawa. Fuentes-Davila, G. and R. Duran. 1986. Tilletia indica cytology and teliospore formation in vitro and in immature kernels. Canadian Journal of Botany. 64(8):1712-1719. Goates, B. J. 1988. Histology of infection of wheat by Tilletia indica, the Karnal bunt pathogen. Phytopathology 78(11):1434-1441. Holmes, G. J., L. F. Jackson and T. M. Perring. 1996. Imperial valley conditions limit Karnal bunt in wheat. California Agriculture 51:29-33. Ibekwe, A.M., S.K. Papiernik, J. Gan, S.R. Yates, C.H. Yang, and D.E. Crowley. 2001. Impact of fumigants on soil microbial communities. Applied and Env. Microbiology 67:3245-3257. Kumar, J. and S. Nagarajan. 1998. Role of flag leaf and spike emergence stage on the incidence of Karnal bunt in wheat. Plant Disease 82(12):1368-1370. Kutilek, V., R. Lee and G. B. Kitto. 2001. Development of immunochemical techniques for detecting Karnal bunt in wheat. Food and Agricultural Immunology 13(2):103-114. Levy, L., L. A. Castlebury, L. M. Carris, R. J. Meyer and G. Pimentel. 2001. Internal transcribed spacer sequence-based phylogeny and polymerase chain reaction-restriction fragment length polymorphism differentiation of Tilletia walkeri and T. indica. Phytopathology 91(10):935-940. Luster, D. G., M. R. Bonde, G. L. Peterson, M. A. Hack and N. W. Schaad. 1998. Antigenic glycoproteins in the teliospore wall of Tilletia indica. Mycologia 90(2):180-188. McDonald, J. G., E. Wong, G. T. Kristjansson and G. P. White. 1999. Direct amplification by PCR of DNA from ungerminated teliospores of Tilletia species. Canadian Journal of Plant Pathology 21(1):78-80. McDonald, J. G., E. Wong and G. P. White. 2000. Differentiation of Tilletia species by rep-PCR genomic fingerprinting. Plant Disease 84(10):1121-1125. Pimentel, G., L. M. Carris, L. Levy and R. J. Meyer. 1998. Genetic variability among isolates of Tilletia barclayana, T. indica and allied species. Mycologia 90(6):1017-1027. Poe, S. 1998. APHIS response to Karnal bunt prior to March 1996. Pages 107-111 In: Proc. Bunts and Smuts of Wheat: An International Symposium. North Carolina. North American Plant Protection Organization, Ottawa. Rajaram, S. and G. Fuentes-Davila. 1998. Development of wheat varieties with resistance to Karnal bunt. Pages 305-316. In: Proc. Bunts and Smuts of Wheat: An International Symposium. North Carolina. North American Plant Protection Organization, Ottawa. Roberson, R. W. and E. S. Luttrell. 1987. Ultrastructure of teliospore ontogeny in Tilletia indica. Mycologia 79(5):753-763. Rossi, R. E., D. J. Mulla, A. G. Journel and E. H. Franz. 1992. Geostatistical tools for modeling and interpreting ecological spatial dependence. Ecological Monographs 62(2):277-314. Royer, M. H. and J. Rytter. 1985. Artificial inoculation of wheat with Tilletia indica from Mexico and India. Plant Disease 69:317-319 Royer, M. H. and J. Rytter. 1986. Relationship between kernel infection and spike infection of wheat by Tilletia indica, causal agent of Karnal bunt. Plant Disease 70(3):225-228. Sansford, C. E. 1998. Karnal bunt (Tilletia indica): An assessment of the significance of the initial detection of Tilletia indica Mitra in the USA in early 1996 and the potential risk to the United Kingdom (and the European Union). Pages 273-302. In: Proc. Bunts and Smuts of Wheat: An International Symposium. North Carolina. North American Plant Protection Organization, Ottawa. Sawyer, A. J., R. N. Huettel and R. J. Meyer. 1997. Detection sampling for teliospores of Tilletia indica (Karnal Bunt) and infected kernels in bulk grain. Phytopathology 87:S85 Sawyer, A. J., R. N. Huettel and R. J. Meyer. 1997. Within-field spatial distribution of Tilletia indica (Karnal Bunt):implications for detection surveys. Phytopathology 87:S85 Sekhon, K. S., S. K. Randhawa, A. K. Saxena and K. S. Gill. 1981. Effect of washing-steeping on the acceptability of Karnal bunt infected wheat for bread, cookie and chapati making. Journal of Food Science and Technology 18(1):1-2. Sekhon, K. S., N. Singh and R. P. Singh. 1992. Studies on the improvement of quality of wheat infected with Karnal bunt. I. Milling, Rheological, and Baking Properties. Cereal Chemistry 69(1):50-54. Sequeira, R. 2001. An epidemiological approach to assessing the risk of establishment of Karnal bunt, Tilletia indica (Mitra), in North America. http://www.nappo.org/menu_e.shtml Singh, A. 1994. Epidemiology and management of Karnal bunt disease of wheat. G.B. Pant University of Agriculture and Technology Research Bulletin No. 127 Singh, B. B., S. S. Aujla and I. Sharma. 1993. Integrated management of wheat Karnal bunt. International Journal of Pest Management 39(4):431-434. Singh, D. V. 1981. Studies on Karnal bunt of wheat I. Standardization of techniques for seed sampling and minimum working sample. Seed Research 9(1):76-80. Singh, N., K. S. Sekhon, A. K. Srivastava and P. P. Gupta. 1992. Studies on the improvement of quality of wheat infected with Karnal bunt. II. Nutritional and biological effects. Cereal Chemistry 69(1):55-60. Singh, P., H. S. Sohi and P. S. Bedi 1983. Effect of Karnal bunt of wheat on seed viability, embryo vigour and metabolism of plants. J. Res. Punjab Agric. Univ. 20(4):481-484. Smilanick, J. L., J. A. Hoffmann, N. L. Cashion and J. M. Prescott. 1987. Evaluation of seed and foliar fungicides for control of Karnal bunt of wheat. Plant Disease 71(1):94-96. Smilanick, J. L., J. A. Hoffmann and M. H. Royer. 1985. Effect of temperature, PH, light, and desiccation on teliospore germination of Tilletia indica. Phytopathology 75(12):1428-1431. Smiley, R. W. 1997. Risk assessment for Karnal bunt occurrence in the Pacific Northwest. Plant Disease 81(6):689-692. Smith, O. P., G. L. Peterson, R. J. Beck, N. W. Schaad and M. R. Bonde. 1996. Development of a PCR-based method for identification of Tilletia indica, causal agent of Karnal bunt of wheat. Phytopathology 86(1):115-122. Vandemark, G. J., J. M. Kraft, R. C. Larsen, M. A. Gritsenko, and W. L. Boge. 2000. A PCR-based assay by sequence-characterized DNA markers for the identification and detection of Aphanomyces euteiches. Phytopathology 90:1137-1144. Vocke, G., E.W. Allen, and J.M. Price. 2002. Economic analysis of ending the issuance of Karnal Bunt phytosanitary wheat export certificates. Warham, E. J. 1986. Karnal bunt disease of wheat: a literature review. Tropical Pest Management 32(3):229-242. Warham, E. J. 1990. A comparison of inoculation techniques for assessment of germplasm susceptibility to Karnal bunt (Tilletia indica) disease of wheat. Annals of Applied Biology 116(1):43-60. Warham, E. J. 1990. Effect of Tilletia indica infection on viability, germination, and vigor of wheat seed. Plant Disease 74(2):130-132. Warham, E. J., A. Mujeeb-Kazi and V. Rosas. 1986. Karnal bunt (Tilletia indica) resistance screening of Aegilops species and their practical utilization for Triticum aestivum improvement. Canadian Journal of Plant Pathology-Revue Canadienne De Phytopathologie 8(1):65-70. Winton, L. M., J. K. Stone, L. S. Watrud, and E. M. Hansen. 2002. Simultaneous one-tube quantification of host and pathogen DNA with real-time polymerase chain reaction. Phytopathology 92:112-116. Ykema, R. E., M. E. Palm and G. L. Peterson. 1996. First report of Karnal bunt of wheat in the United States. Plant Disease 80(10):1207-1207.

Attachments

Land Grant Participating States/Institutions

AR, KS, MO, OK, SD, TX

Non Land Grant Participating States/Institutions