Small Grains Plant Pathology Projects...

I. Research Activities

Production acreage of small grain crops has declined in Minnesota during the last decade because of repeated yield and grain quality losses caused primarily by Fusarium head blight (FHB). These losses have caused grain production profit margins to be slim to nil. Therefore, as an extension plant pathologist, I realize it is impractical to recommend use of fungicides to protect a crop when an input cost exceeds the potential economic benefit. My research focuses on the development of economical as well as sustainable disease management strategies. Key components of an integrated disease management program include: (a) identification of important diseases and determination of their prevalence; (b) establishment of long-term management strategies for reducing crop inputs; and (c) development of short-term management strategies to ensure a safe and continuous food supply. My research program contains projects that address all three of these components. Since 2002, data produced from my program have contributed to improved disease management in the Red River Valley (RRV). Outcomes of my research program have provided the agricultural community with data to make informed decisions at pre-planting, such as cultivar selection, all the way through post harvest management, including metrics for increasing revenue generation per acre. Thus, my research program supports my extension responsibilities and personal goal of developing practical, sustainable disease management recommendations for crop production in the RRV region. Those diseases targeted by my research include: FHB and aster yellows of wheat and barley; tan spot, leaf rust, Septoria tritici blotch, and brown root rot of wheat; Septoria speckled leaf blotch and net blotch of barley; damping off and fungal root rot complexes of soybean; Sclerotinia head rot of sunflower; and brown root rot of alfalfa. Research projects summarized below convey progress made toward reaching my programmatic goals.

A. Program Goal: Identification of important diseases and determination of their prevalence

Objective 1. Disease detection and diagnosis

Disease detection and diagnosis are crucial in understanding why, how, and where crop losses occur. Throughout my career, I have gained particular expertise and become nationally recognized for my research on aster yellows of wheat and for brown root rot of alfalfa and winter wheat.

Project 1a. Aster yellows of small grain crops

During 2002, aster yellows phytoplasma (DNA-delineated group, or subclade, of 16SrI) was confirmed in symptomatic spring wheat plants growing in northwestern Minnesota . Symptoms included a unique red-to-purplish leaf discoloration similar to that caused by barley yellow dwarf virus, a pathogen responsible for another insect-vectored disease in the state. Multi-year (2003 to 2006) research funding was obtained from the Minnesota Wheat Research and Promotion Council, University of Minnesota Grant-in-aid program, and Agricultural Utilization Research Institute. A major objective of this research was to determine incidence of the disease and assess its correlation with populations of insect vectors. Based on nested-PCR assays, our results indicated that aster yellows and barley yellow dwarf virus are easily misdiagnosed, and immigrant aster leafhoppers originating from southern states are likely spreading the disease earlier than leafhopper populations emerging from over-wintering sites within Minnesota . Results were presented and discussed at the joint meeting of NCERA-184 and WERA-97 regional diseases of small grains groups held during June of 2007. I am leading an effort to obtain additional funding for an inclusive, national collaborative research effort on aster yellows in small grains.

Publication outcome:

•  manuscript accepted by Plant Disease

•  chapter accepted in Compendium of Wheat Diseases and Insects

•  poster presentations resulting in five scientific conference papers

•  topic in numerous extension articles and presentations

Project 1b. Brown root rot of alfalfa and winter wheat crops

  During 2003, I identified Phoma sclerotioides , the causal organism of brown root rot of alfalfa in commercial production fields in northwest Minnesota . This discovery led to a multi-year research collaboration led by Dr. Deborah Samac, USDA-ARS which was funded twice by the University of Minnesota Rapid Agricultural Response Fund . Research objectives initially focused on disease distribution and diagnoses, but have been broadened to include investigation into management strategies. Originally, plant collections made from commercial alfalfa and winter wheat fields were examined in the laboratory to establish pathogen distribution in the Upper Midwest . The fungus was found in association with roots of winter wheat, which was confirmed by Koch's postulates as a new host. Presently, research is underway to identify residues of common crop species that support saprophytic colonization by the fungus to identify rotation crops that support increased, versus decreased, field inoculum levels.

Publication outcome:

•  article published in Plant Disease

•  chapter accepted in Compendium of Wheat Diseases and Insects

•  poster presentations resulting in three scientific conference papers

•  topic in numerous extension articles and presentations

Project 1c. Foliar disease and root rot complex of soybean

Soybean acreage has been increasing in northwest Minnesota as small grain crops acreage declines. Crop losses caused by root rots have developed slowly over the years. During 2004 to 2005, the Minnesota Soybean Research and Promotion Council funded a study to identify common above- and below-ground diseases in the Red River Valley . I led collaborative research that included Dr. Carlyle Holen , IPM specialist, as well as Dr. Hans Kandel and Doug Holen , Regional Extension Educators. Plant samples and cropping histories were collected on a number of commercial fields. Plants in targeted fields were sampled twice during the growing season and examined in the laboratory for foliar and root diseases. Specifically, Fusarium spp. were most commonly isolated from symptomatic roots, with Pythium spp. next in prevalence.

Publication outcome:

•  topic in several extension articles and presentations

•  Farm and Ranch Guide reporter, Andrea Johnson, took an interest in this research and traveled to Crookston to conduct an interview, view plants, and become acquainted with tissue isolation techniques. She produced electronic and hardcopy media articles.

B. Program Goal: Establishment of long-term disease management strategies to support reduced crop inputs

Objective 1. Informed decision making

Disease management decisions for FHB are made days to weeks before disease symptoms develop. Estimating the potential for disease based on the weather and agroecosystem conditions is abstract and difficult. One must understand a myriad of contributory factors including, but not limited to: i ) weather conditions prior to and during the heading (barley) or early-flower (wheat) crop growth stages; ii ) resistance levels for FHB in cultivars; iii ) crop rotation; iv ) yield potential; and v ) grain market prices and trends. Many producers employ crop consultants to assist in the decision-making process. To aid growers in making informed disease management decisions, I established the Minnesota FHB epidemic risk forecasting system. The system is funded by the Minnesota Wheat Research and Promotion Council. The system's website is hosted by a private company, Meridian Environmental Technology, Inc. North Dakota State University (NDSU) provides neural network epidemic risk forecasting models for tan spot, leaf rust, and Septoria leaf blotch, while Kansas State (KSU) and Penn State (PSU) universities provide a FHB epidemic risk forecasting model. Development of, and modifications to, the FHB epidemic risk forecasting model are made by researchers at KSU and PSU and funded by the U. S. Wheat and Barley Initiative. I led the effort to establish the epidemic risk forecasting system in Minnesota , and continue to work with those involved in upgrading the FHB epidemic risk forecasting model.

Project 1a. National epidemic risk forecasting model for wheat

Minnesota contributes disease management data yearly to national FHB epidemic risk forecasting model developers in support of their annual model upgrading effort. Since 2004, this research has been supported by the Minnesota Wheat Research and Promotion Council, and more recently by the U.S. Wheat and Barley Scab Initiative. The on-farm disease management research effort from which this data is derived is described below in the project entitled ‘On-farm disease management experiments of spring wheat'. Because of research data contributed primarily from spring wheat grown in Minnesota , North Dakota and South Dakota , FHB epidemic risk forecasting estimates are no longer based solely on susceptible cultivar responses to the disease, but are instead specified by different resistance levels of each cultivar. This upgrade will likely make epidemic risk estimates more accurate than ever before for the crop.

Publication outcome:

•  article published in Plant Health Progress

•  topic in numerous extension articles and presentations

•  topic of invited presentation at the 5th Canadian Workshop on Fusarium Head Blight held in Canada during November of 2007

Project 1b. National epidemic risk forecasting model of barley

  Since 2005, a research collaboration, initiated by Dr. Jeff Stein of South Dakota State University , was created to develop a FHB epidemic risk forecasting model for barley much like the one for wheat. Funded by the U.S. Wheat and Barley Scab Initiative, this effort is in an initial data collection stage. Experimental plots of barley have been established at multiple Red River Valley locations where weather conditions, disease development, and plant growth stage data are also being collected. In the near future, when a sufficient number of ‘case' data have been established, researchers will develop an experimental FHB epidemic risk prediction model for barley.

Publication outcome:

•  poster presentation resulting in a scientific conference paper

Objective 2. Developing a disease management action plan

An effective disease management strategy utilizes a multiple component approach in controlling, or managing, crop disease. These components can be described broadly as host resistance, cultural management, and chemical/biological management. Of these components, disease resistance is the foundation on which the structure of disease management is built. Resistance represents a biologically and economically sustainable means in which crops are protected from yield and/or quality losses. My research efforts have been directed toward: i ) developing locally successful protocols for disease inoculation in the field for Pyrenophora teres and Stagonospora avenae f. sp. triticea of barley as well as Septoria tritici and aster yellows phytoplasma of wheat; ii ) testing wheat and barley germplasm, sunflower hybrids, and cultivars of wheat, barley, soybean, sunflower, and alfalfa for resistance to important and emerging plant diseases; iii ) determining whether known levels of FHB and leaf spotting disease resistance levels in wheat can adequately protect the crop against losses caused by disease; and iv ) understanding environments where certain levels of wheat, barley, or soybean cultivar resistance supersede benefits from seed and/or foliar treatments of fungicide.

Project 2a. On-farm disease management experiments of spring wheat

This multiple Red River Valley site and year research effort has expanded substantially since its inception during 2004. The Minnesota Wheat Research and Promotion Council has supported the effort, in part, each year. During 2007, the U.S. Wheat & Barley Scab Initiative was added as a funding partner. The effort is in its first research year as a multi-state, collaborative project. Research objectives have not changed, however, and include identification of agronomic and economic outcomes from several integrated disease management strategies of spring wheat. Fungicide treatments range from a nontreated control to multiple applications on cultivars having different levels of disease resistance. Data are collected on weather conditions, disease development, yield, and grain quality. Economic outcomes are determined from graded grain samples, using premium and discount schedules of current cash basis markets. This analysis completes the informational thread all the way from cultivar selection to economic outcome for each disease management strategy. I am a leader, not only regionally, but nationally, in reporting results of plant pathology research to stakeholders in agronomic as well as economic terms. The U.S. Wheat and Barley Scab Initiative has encouraged other researchers to follow my lead and deliver this type of information to producers in their states.

Publication outcome:

•  manuscript accepted by Plant Disease

•  poster presentations resulting in four scientific conference papers

•  a majority of extension articles and presentations are based on this work

•  invited presentation at the 2005 Association of Analytical Chemists International Midwest Section Annual Meeting and Exposition

Project 2b. On-farm disease management experiments of spring wheat germplasm

This study is a parallel effort to the research described in the above project. It is funded by the Minnesota Small Grains Initiative. Wheat germplasm entries from public and private plant breeder collaborators are being tested for their disease management outcomes at multiple sites in the Red River Valley . Entries are expected to become commercially available in approximately one to two years from test initiation. Currently in its first year, this experiment was planted at two on-farm test locations. Fungicide treatments were applied to represent commonly practiced disease management strategies for the area. Weather conditions, disease development, yield, and grain quality will be recorded and evaluated. This effort will determine germplasm entry performance in Red River Valley environments and establish each entry's response to different disease management strategies.

Project 2c. On-farm disease management experiments of barley cultivars and germplasm

Current malting barley cultivars are susceptible to FHB. Without resistant cultivars, adequate management of the disease is not achievable. During 2007, an on-farm integrated disease management experiment was begun to compare several malting barley cultivars with a promising group of elite breeding lines originating from breeding programs at Busch Agricultural Resources, Inc. ( BARI ), North Dakota State University , and the University of Minnesota . Funded by BARI , the objective of this experiment is to determine if grain quality and malting characteristics of experimental lines are adequately protected against FHB by using an integrated disease management approach. Among the management treatments tested, a promising new fungicide product is being tested at low and high label rates.

Project 2d. Disease nursery testing of malting barley germplasm

Harvested acreage of malting barley in Minnesota has declined an estimated 38% during the last seven years (2000 to 2007). Much of the reduction is attributed to deoxynivalenol, a toxin responsible for causing food and feed safety concerns. The toxin is found in grain infected by Fusarium graminearum , the primary causal organism of Fusarium head blight in the U. S. Since 2003, I have collaborated with BARI to evaluate their elite and advanced malting barley breeding lines for Fusarium head blight and net blotch in disease nurseries located at Crookston and Stephen , MN . Early generation barley crosses between BARI materials and international germplasm sources (ICARDA and CIMMYT) have been added to the test during the last few years.

Publication outcome:

•  poster presentation resulting in a scientific conference paper

Project 2e. Disease nursery testing of experimental wheat and barley lines

  From 2004 to 2007, I supervised the University of Minnesota disease nurseries research effort located in Northwest Minnesota , which was funded by the Minnesota Small Grains Initiative, U.S. Wheat & Barley Scab Initiative, and Minnesota Agricultural Utilization Research Institute. The disease nurseries are research support tools for University of Minnesota wheat and barley breeders, Drs. James Anderson and Kevin Smith, and their collaborators. Under my management, select entries were tested for Septoria speckled leaf blotch of barley, net blotch of barley, Septoria tritici blotch of wheat, and Fusarium head blight of wheat and barley.

Publication outcome:

•  a poster presentation

•  topic in several extension articles

Project 2f. Disease nursery testing of sunflower hybrids

Sunflower acreage trends have been variable in Minnesota across the last couple of decades because of severe and unpredictable pest issues. In spite of the crop's production setbacks, sunflower acreage has trended upward the last decade. During 2005, approx. 135,000 acres of oil and non-oil sunflowers were planted. This represents a nine year rally for sunflower production acreage in Minnesota and resulted in an estimated $26.2 million in farm income. Sclerotinia head rot has been one of the most economically significant diseases of the crop in Minnesota during recent years, and represents a major production issue for RRV producers. Funded by the National Sclerotinia Initiative and the National Sunflower Association, the objective of this project is to evaluate public and private hybrid sunflower germplasm entries for Sclerotinia head rot resistance. More than 20 and 70 hybrid lines were tested for resistance during 2006 and 2007, respectively. My inclusion in this research effort is a direct result of supportive, private sunflower industries located in northwest Minnesota . The collaborative effort includes researchers from Agriculture and Agri-Food Canada , North Dakota State University , and the USDA-ARS Sunflower Unit. Results from last year's effort indicate several promising hybrids exist for Sclerotinia head rot management in Minnesota .

Publication outcome:

•  poster presentations resulting in two scientific conference papers

•  topic in several extension articles and presentations

C. Program Goal: Development of short-term disease management strategies to ensure a safe and continuous food supply

Objective 1. Disease management via fungicide application

The level of disease control achieved from an application of fungicide can be dramatic and immediate, but depending on the life cycle of the pathogen and the fungicide used, the control interval may be brief. Nevertheless, fungicides are a commonly used component of integrated disease management strategies. Unfortunately, FHB is not reliably controlled by fungicide application. To obtain the best results, fungicide application must be: i ) timely; ii ) reinforced by cultivar disease resistance; and iii ) at full label rate with droplets deposited as much as possible on plant glumes. The research described below represents projects investigating fungicide application technologies and product efficacies.

Project 1a. Uniform fungicide trials on wheat and barley

Crop protection chemicals have been, and remain, an important component in managing grain yield and quality losses caused by FHB. Since 2003, multi-state collaborative research has been conducted with support from the U.S. Wheat and Barley Scab Initiative. Treatments of experimental and pre-registration fungicide active ingredients were compared to nontreated control and industry standard fungicide treatments. Disease development, yield, and grain quality were analyzed by collaborators and data are combined across environments by a lead researcher. Data are being used by the crop protection industry to support EPA product registration applications of fungicide and by state extension plant pathologists for EPA Section 18 Emergency Exemption Use requests. This work has been instrumental in obtaining Minnesota 's annual Section 18 registrations for the use of tebuconazole fungicide on wheat and barley to manage FHB.

Publication outcome:

•  article published in Plant Health Progress

•  seven edited technical reports published

•  poster presentations resulting in seven scientific conference papers

•  topic in numerous extension articles and presentations

Project 1b. Aerial application technologies of fungicide

  Management of Fusarium head blight depends on a timely application of fungicide as well as a uniform deposition pattern of droplets on plant glumes. New fungicide active ingredients with greater potentials for FHB disease management are limited, making it imperative that existing fungicides be applied to achieve maximum disease control. Supported by the U.S. Wheat and Barley Scab Initiative, this two year project was a multi-state collaborative effort between agricultural engineers and plant pathologists at the University of Minnesota , North Dakota State University , Michigan State University, and the USDA-ARS Aerial Application Research Unit located at College Station , Texas . The objective of this research was to determine if alternative aerial application technology strategies could enhance FHB management in spring wheat. Research was conducted in field-scale experiments at a location in Minnesota and two locations in North Dakota . Droplet size and spray dilution treatment combinations were tested. This research established that the current industry standard aerial application method is comparable or better than other treatments tested.

Publication outcome:

•  manuscript published in Applied Engineering in Agriculture

•  poster presentations resulting in two scientific conference papers

•  topic in numerous extension articles and presentations

Project 1c. The role of fungicides in grain accumulation of deoxynivalenol (DON)

Disease management research described previously in the ‘ On-farm disease management experiments of spring wheat ' project indicated that an application of a strobilurin fungicide on spring wheat at the flag leaf crop growth stage contributes to increased DON content in grain compared to nontreated control treatments. The objective of this experiment is to determine if relationships exist between host resistance, fungicide application, environmental conditions, and DON accumulation in wheat and barley grain. Begun in 2007, the research project is funded by the U.S. Wheat and Barley Scab Initiative.

Project 1d. Determining the disease management potential of experimental and newly registered fungicides in Minnesota

  My research program contributes disease management efficacies for fungicide products tested in Minnesota that are submitted for evaluation by private industry. Timing and rates of fungicide application vary from product to product. Disease development, yield, and grain quality data are collected. These experiments provide an opportunity to become familiar with experimental and newly labeled fungicide products, enhancing my understanding of the crop protection industry, and strengthening my extension program. During 2006, several companies supported an integrated disease management experiment whereby a relationship between product efficacy and level of cultivar resistance to FHB was investigated. These companies regularly support my program's yearly on-farm disease management research. I have worked with a total of nine companies since 2003.

Publication outcome:

•  topic in numerous extension presentations

Project 1e. Disease management strategies for root rots of soybean

Red River Valley soils are high in clay content and generally poorly drained. Soybean root rot diseases are responsible for the largest disease-associated yield limitation in northwest Minnesota . Reducing crop losses caused by root disease is important in a production area known for comparably lower yields simply because of its latitude. Since 2006, my program has collaborated with Dr. Dean Malvick, University of Minnesota , to investigate crop responses following seed-applied and/or drench-applied fungicide treatments. The objective of this study is to determine the effects of root pathogens on plant health and crop production. Because surviving plants often produce greater yields when in proximity with infected dead plants, yield losses from root rots are often difficult to quantify. This study was designed to promote an understanding of this plant compensation phenomenon by testing higher and lower planting populations within each fungicide treatment. Plant stand counts, root disease development, Rhizobia nodulation, and yields are being evaluated. This research is being supported by the Minnesota Soybean Research and Promotion Council.

Publication outcome:

•  one extension article

Project 1f. Determining crop losses resulting from cold water imbibition of soybean seed

Producers in northwest Minnesota constantly try to lengthen the growing season by planting earlier. Placing soybean seed into cool, moist soils is expected to increase the risk for pre- and post-emergence damping off diseases. Replicated research data is not available from field experiments conducted in the Red River Valley that establish whether crop losses result from this practice. Greenhouse research in Canada indicates that seed coat injury and loss of plant exudates occurs after seeds imbibe cool soil water. Funded by the Minnesota Soybean Research and Promotion Council, the objective of this field research is to determine the potential for crop loss resulting from soybean seed imbibition of water at different temperatures. Additionally, management strategies are being investigated to determine if cultivar and/or fungicide seed treatments influence seed injury outcomes. Data on soil temperature, stand counts, seedling vigor, root health, harvest yield and soybean quality are being collected.

Publication outcome:

•  one extension article

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