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Ontario Grain Farmer Magazine

Soybean seedling disease management

Principal Investigator

Albert Tenuta* & Jason Bond

Research Institution

Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA)* / Southern Illinois University

External Funding Partners

Canadian Agricultural Adaptation Program (CAAP). Investment in this project is provided by AAFC through the CAAP. In Ontario, this program is delivered by the Agricultural Adaptation Council.

Funding for the collaborating US partners and publications was through United Soybean Board (USB), North Central Soybean Research Program (NCSRP) and the USDA-NIFA Coordinated Agricultural Program (CAP).

Project Start

May 2012

Project End

February 2015

Objectives

  • Identify fungi responsible for causing seedling blights of soybean.
  • Develop high throughput diagnostic tools for identification of fungal seedling pathogens.
  • Characterize the biology of seedling pathogens and develop assays for inoculation.
  • Identify the impact of environmental conditions on seedling pathogens and epidemiology.

Impact

  • The understanding of the distribution of the various pathogen species (Fusarium, Phytophthora, Pythium, Rhizoctonia, etc) can be used by growers to implement an Integrated Pest Management (IPM) strategy to choose appropriate disease management solutions, such as fungicide seed treatments that are tailored by region to have maximum efficacy and disease reduce losses.
  • The information gathered will also assist soybean breeding for more efficient soybean variety development, by allowing breeders to screen varieties with the pathogen species found in area region; this will lead to more consistent disease ratings for growers since results indicate differences in pathogen populations between regions based on soil temperature and latitude.
  • The development of a rapid and cheap soil assay detection method for Pythium and Phytophthora species which will help growers to choose the most effective seed treatments and varieties for an individual field thereby limiting losses and improving early season stand establishment.
  • The collaboration efforts between US and Ontario researchers will increase efficiencies and communication, such as the production of new extension publications based on results were developed and distributed in Ontario and the US.

Scientific Summary

Soybean is a high value crop in Ontario that is heavily impacted by root and stem rot diseases caused by Fusarium, Rhizoctonia, Phytophthora sojae and by several Pythium species. Seedling diseases rank in the top five disease threats to soybean production in North America and number two after soybean cyst nematode in Ontario. Soybean losses to seedling diseases have increased as a result of lack of resistance genes for Rhizoctonia, Pythium and Fusarium as well as resistance genes are losing their effectiveness against Phytophthora in many parts of Ontario. Moreover, increasing adoption of early planting and no-till farming has also increased soybean losses due to soil-borne diseases. Increasing competition for the soybean crop from industrial and bioenergy uses has put further pressure on soybean production for food and animal feed. Producing high soybean yields begins with establishing an even stand of vigorous plants. Seedling diseases, poor seed quality, and the environment often interact and lead to reduced stand establishment, plant health and vigor, with these factors often interacting to reduce emergence. Unfortunately, there is much we do not know about these factors.

This three year project aimed to address these production constraints by identifying the causal agents of seedling disease, developing new tools for rapid diagnosis, developing new protocols for research and for germplasm screening assays, and developing management recommendations and extension materials for producers and the industry. This project is progressing to help better understand the environmental conditions and cropping practices that are responsible for reducing or increasing the pathogens and impact on disease development. The research group has been perfecting techniques to isolate organisms, developing inoculation assays and identifying better inoculum carriers. One of the primary goals was to develop future protocols for soybean germplasm screening. The use of fungicide seed treatments has increased over the past decade in the region and in Ontario it is a necessary production cost not only to maximize early season stand establishment but yield and quality as well. Ontario work conducted through this project was instrumental in getting a new active ingredient (ethoboxam) registered for Canada by Valent Corporation. Research conducted in this project continues to determine how the most common fungicides impact various pathogens. Although baselines fungicide sensitivity studies continue which will allow researchers to determine if seedling pathogens are developing resistance to fungicides over time, early results do show some level of resistance has developed. In fact, this project has found species of Fusarium, Pythium and Rhizoctonia that are not sensitive to major fungicides. This could have a negative impact on our ability to control these pathogens and unfortunately will impact yield as these species become more common.

An important aspect of this three year project was to foster communication and cooperation between the various researchers in the 13 participating states and Ontario. Many of these researchers have been working on aspects of this research for several years. This collaboration allows for greater efficiency and communication as well as join in these larger funded projects (USB/NCSRP over $1.5M for 3 years) and the Oomycete-Soybean Coordinated Agricultural Project (CAP), a transdisciplinary effort of 28 co-project researchers at 17 US institutions (funding $9,000,000 USD). This project has led to increased communication and coordination among universities and has enabled this team to make significant progress.

Development of extension publications continued in project supported by Grain Farmers of Ontario, titled “Soybean Seedling Diseases – Characterization and Education” (April 2015 – March 2018).

Project Related Extension Publications

“Scouting for Common Soybean Seed Diseases” CPN 1001 available on CPN website and Grain Farmers of Ontario’s Production Resources page.

“Scouting for Phytophthora Root and Stem Rot in Soybean” CPN 1014 available on CPN website.