Database Research SummariesMulti-Pronged Strategies to Provide Durable Control of Sclerotinia Stem Rot
Research Focus
The incidence of Sclerotinia stem rot (SSR, also called “white mold”) is highly dependent on specific environmental conditions necessary for infection. In instances where flowering coincides with cooler temperatures and extended surface wetness, disease severity can be significant. The sporadic nature of the disease results because these weather conditions must be present at the time of soybean flowering. If they are absent, then Sclerotinia stem rot is unlikely to occur. This makes the disease difficult to predict and manage.
The goal of this proposal is to provide growers with more concrete management options for Sclerotinia stem rot of soybean in the North Central region. It also provides specific information on tools that can be used to incorporate host resistance into commercial varieties against white mold disease.
Objectives
Objective 1. To evaluate current, standard soybean management practices, including irrigation, row spacing, population density, and fungicide treatment applied using an advisory tool, for use in integrated Sclerotinia stem rot management.
Objective 2a. To identify new germplasm lines resistant to Sclerotinia sclerotiorum that can be incorporated into integrated management programs or into soybean breeding programs.
Objective 2b. To refine the existing soybean SSR advisory tool to incorporate model output for different forms of resistance.
Objective 3. Exploitation of transgenic soybean silenced in NADPH oxidases to achieve abiotic and biotic stress tolerance.
Objective 4a. Develop outreach publications and tools based on results generated here and disseminate through the national Crop Protection Network portal.
Objective 4b. Develop an electronic book compiling information about Sclerotinia stem rot and management of the disease for a diverse audience.
Results
- In the past two years, planting at 140,000 seed per acre, we found that yield is typically high in 15” row spacing, however, white mold can be as high as 50% greater in a 15” row spacing compared to 30” row spacing.
- In field screening of resistant lines compared to a susceptible check (Jung 1212R2X), several commercial varieties were identified that appear to have good physiological resistance in the greenhouse and acceptable field resistance in multiple field environments. Testing will continue in 2019.
- The “Sporecaster” smartphone application was made available to the public as a free download on the Google Play Store and iPhone app store in May, 2018. a As of this report, Sporecaster was downloaded over 1,600 times from the Apple and Android stores. Daily use rates during the major “white mold season” (July and August) averaged 250 users per day. https://ipcm.wisc.edu/apps/sporecaster/
- In the 2018 validations of 16 commercial fields, Sporecaster was accurate ~80% of the time in predicting yield-limiting epidemics.This level of accuracy is good, however, we believe that incorporating varying levelsof resistance into the model, such as illustrated in objective 2a, could further improve the accuracy.This could be done by modifying the action thresholds based on resistance type. Work is underway to understand how this could be implemented.Finally, Sporecaster received the 2018 American Society of Agronomy (ASA) Extension Education Community Educational Award in the category of digital decision aids (software, web-based, smartphone and tablet apps). This was awarded at the annual meeting of the ASA in Baltimore, MD in November
- Once Sporecaster recommends a fungicide application, Sporebuster can be used to determine a profitable program. Sporebuster has been available for just two months (since October 2018). This application has been downloaded approximately 70 times. Sporebuster is used to determine if a crop is at risk for whitemold and advises if a fungicide application should be made. This app is meant to be run in-season and uses site-specific weather information to provide the risk prediction. Sporebuster is meant to complement Sporecaster. Sporebuster is a return on investment application that uses research-based economic models to determine if a particular fungicide program for white mold control, will result in a high probability of success on a case-by-case basis. Users can input their costs for programs and uses their own yield and soybean pricing scenarios to get tailored recommendations.https://ipcm.wisc.edu/apps/sporebuster/
The purpose of Sporebuster is to assist soybean farmers in making a fungicide program decision that is profitable for their operation. Sporebuster is meant to complement Sporecaster, which is a tool that can be used to make the decision whether a fungicide application is even needed. Once Sporecaster recommends a fungicide application, Sporebuster can be used to determine a profitable program. To learn more about Sporebuster, how to use it, and to download it, click here.
Importance
- Growers will have more chemical, genetic, and cultural management options for Sclerotinia stem rot of soybean.
- The extreme variability in the development of SRR from year-to-year makes it hard to know if and when fungicide applications would be effective.
- The use of the smart phone application SPORECASTER developed in this project will allow for precise detection of risk areas and efficient deployment of fungicides.
- Unnecessary fungicide applications can be avoided, for example when weather conditions are not conducive to apothecia production during flowering.
For more information about this research project, please visit the National Soybean Checkoff Research Database.
Funded in part by the soybean checkoff.
