White Mold NCSRP Research

Update of the North Central Soybean Research Program (NCSRP).

The NCSRP met in August of 2019 for its annual research funding meeting. With fewer checkoff dollars available, due to the downturn in the market, the NCSRP employed greater discretion in the selection process. Thanks to some additional funds from the United Soybean Board (USB), the NCSRP was able to fund 11 of the 24 submitted projects. This year’s selected projects span an array of topics including soybean cyst nematode, soybean sudden death syndrome, genetic work for yield gain and protein increase, and many others. To see the full list of projects funded by the NCSRP please visit NCSRP.com.

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The NCSRP has two projects in particular that will have an immediate return on investment for the Wisconsin Soybean Producer. The first is an all avenues approach to battling white mold and was submitted by Damon Smith, Field Crops Pathologist at UW Madison.

Project Title: Multi-pronged strategies to provide efficient, sustainable, and durable control to Sclerotinia stem rot

Principal Investigator: Damon Smith, University of Wisconsin-Madison

Co-Principal Investigators: Mehdi Kabbage, University of Wisconsin-Madison; Daren Mueller, Iowa State University; Martin Chilvers Michigan State University

One way to manage white mold of soybean is through cultivar resistance. The development of resistant varieties has proven difficult. Our laboratories have worked hard recently under support from the Wisconsin Soybean Marketing Board (WSMB) and Wisconsin Crop Improvement Association (WCIA) to develop new, non-GMO varieties of soybean with resistance to white mold. Recently we released Dane as a non-GMO food-grade soybean and additional agronomically superior, conventional soybean varieties. In addition to Dane, we have identified the germplasm line 52-82B as highly resistant to white mold and agronomically desirable. We have also identified SSR51-70 and 51-23 as moderately resistant to white mold and have used these in follow-up experiments and crosses to further improve variety resistance. We believe that these three germplasm lines (52-82B, SSR51-70, and 51-23) can be paired with a known susceptible public cultivar (Dwight) and be used as a “check panel” for evaluating white mold resistant varieties and in management experiments such as those described below. We can then use this check panel to also adjust our white mold forecasting tool, Sporecaster, based on the resistance level. We believe that adding this adjustment to our smartphone app will help improve accuracy above what is currently achieved. We are currently investigating these options for adjusting the tool.

In addition to the work to integrate resistance into forecasting, an additional goal is to integrate resistant varieties into agronomic studies. Through work supported by WSMB and NCSRP, we have built upon our knowledge of integrating row-spacing and planting populations for the management of white mold. We know that row spacing greatly influences the appearance and timing of the onset of apothecia (mushroom-like structures that release spores). This is mainly due to changes in the quantity of light as rows close. Delaying row closure can delay the development of the mushroom-like structure (apothecia), which is responsible for releasing spores of the white mold fungus. One additional mechanism for reducing and slowing apothecial onset under 30-in rows is that the quality of light is different in this planting scenario vs. 15-in. rows. Microclimate under 30-in rows is less conducive for the white mold pathogen, compared to 15-in. rows. However, light changes likely influence the development of apothecia as well. We have investigated this in previous iterations of these studies. The lowest number of apothecia were observed in plots where soybeans were planted in 30-in rows and at the lowest planting-population (110,000 seeds/a). Subsequently, this resulted in some of the lowest disease severity index scores. From other analyses, we know that when the disease severity index units are below 20 it is difficult to detect any discernable yield reduction from the white mold. Thus, soybeans planted at 110,000 seeds/a to 140,000 seeds/a in a 30-inch row spacing had levels of white mold generally at or below yield-reducing levels. Yield ranged from the low-to-mid 50 bu/a in the 30-in. row spacing and lower planting-populations. A marginal yield improvement was observed as the planting population increased in the 30-in row spacing. In general, row-spacing had the greatest influence on reducing disease index scores and maintaining yield, with disease index score averaging 50% lower in the 30-in row spacing compared to the 15-in row spacing. Secondarily, dropping the planting population below 140,000 seeds/a can further reduce white mold severity.

White mold has been a consistent threat in the North Central Region in recent years. Thus, the information gained from this integrated white mold management work will help to inform farmers about tools that can be used to reduce damage by the white mold pathogen.

The second project, submitted by Shawn Conley, UW-Madison’s Soybean and Small Grains Specialist, continues work from the past three years gathering on-farm data to figure out the “yield gap” from current yield in soybeans to the potential yield.

Project Title: Boots on the Ground: Validation of Benchmarking Process through an Integrated On-Farm Partnership

Project Justification and Rationale:

Traditional field research has relied too much on trial and error, with little capacity to extrapolate results to farmer fields and quantify impact relative to enhancing net profit. There is an opportunity to make field research more efficient and impactful. To this end, analysis of producer survey data performed during our previous 3-year NCSRP-funded benchmarking project revealed: (1) an average yield gap of 20-30% between current farmer yield and potential yield, and (2) several agronomic practices that, for a given region, can be fine-tuned to close the gap and improve soybean producer profit. In the “Boots on the ground” project, we leverage on the previous investment made by NCSRP by working with on-farm groups to bring the yield gap analysis “back to the farm”. The 3-year collaborative (interdisciplinary and interuniversity) regional project includes on-farm research networks in NE, WI, OH, MI, IA, MN, and ND. In this project, our goal is to show how the producer survey data can be used to identify and strategically evaluate management changes in on-farm trials across the US NC region.

First-year (2019) preliminary results show a large yield benefit (> 5 bu/ac) due to the use of the recommended management practices (identified form the previous NCSRP benchmarking project) across the NC US region. This translated to significant economic benefits for 88% (profit difference from control > 0 $/ac) of participating farmers. At the end of the 3 years of the project, we anticipate being able to demonstrate the combination of management factors in each state (and across the US NC region) that can be used by individual producers to increase on-farm soybean yield, input-use efficiency, and net profit while minimizing the environmental footprint.

These two projects are going to give the Wisconsin Soybean Producer a quality return on investment of not only their checkoff dollar but also their day-to-day decision making on the farm. More information about what the NCSRP is funding is available at our website NCSRP.com. If there is any kind of soybean issue going on in your field, go to soybeanresearchinfo.com and search the database by region and issue.