Battle for the Belt: Season 2 Episode 9- Planting Date & Disease

Episode 9 of Battle for the Belt is now available: https://www.youtube.com/watch?v=I3zTyGvt1_s

In Episode 9, Dr. Horacio Lopez-Nicora, Ohio State Extension Soybean Pathologist, and PhD student, Jenna Moore, speak about early planting considerations for disease management and a couple of current research projects in their lab.

Early Planting Considerations:

Figure 1. Disease triangle showing three required components (susceptible host, virulent pathogen, and conducive environment for disease to occur.

Understanding how to manage diseases is hinged on the disease triangle. Diseases occur when all three components of the disease triangle intersect: a susceptible host plant, a virulent pathogen, and conducive/favorable environmental conditions (Figure 1). These components must align for disease to develop. For example, soil-borne pathogens like Phytophthora and Pythium can cause severe stand reduction, particularly in warm soil temperature fields with poor drainage that allow for sitting water. On the other hand, the fungus that causes sudden death syndrome (SDS), can cause more severe disease under cool and wet conditions but become less of a problem as the soil warms and dries out.

Early planting in Ohio generally means that you will likely plant soybeans in cool and wet soils, which can make the perfect environment for some of our most detrimental diseases.

To manage these diseases, you need to know your field history and which diseases you are dealing with because each disease can be mitigated by using different resistant varieties and seed treatments to protect the crop. 

SCOUTING every year is extremely important to be able to identify disease pressure and create a management plan for that field. Identifying soil-borne diseases can be challenging during the scouting process due to their similar symptoms. If help with diagnosis is needed, samples of affected plants can be sent to the Ohio State Soybean Pathology and Nematology laboratory. It is essential to have a laboratory validate and confirm the disease diagnosis. With the support of the Ohio Soybean Council, soybean growers from all over the state can once again submit soybean samples showing symptoms of sudden death syndrome (SDS) to the laboratory. We look forward to receiving your SDS samples! You can conveniently complete the SDS submission form and send your samples to:

Attn: Horacio Lopez-Nicora, Ph.D. (lopez-nicora.1@osu.edu)
110 Kottman Hall 
2021 Coffey Rd., Columbus, Ohio 43210

After properly identifying the disease there are three main practices to fight these diseases. The first is soybean variety selection. Choosing a soybean variety that is resistant to the specific pathogen you are dealing with is one of the most important disease management decisions. The second is using a disease-specific seed treatment. And finally, well-drained soils to avoid compaction and saturation.

Battle for the Belt Disease Update:

Corn and soybean seedling samples are collected within seven days after the emergence of all five planting dates at each location in order to identify diseases in the plants and surrounding soil. Two different approaches are implemented to evaluate the samples: a traditional approach involving plating and growing the pathogen for molecular diagnosis, and a metabarcoding approach that extracts DNA and characterizes the microbial community present in a sample.

In 2023, we observed different structures in the microbial community of seedlings and soil, depending on the planting dates, locations, and crops. Last year we experienced a cool and wet early season, followed by a prolonged dry spell during planting, resulting in an increased prevalence of organisms such as Rhizoctonia. Consequently, the presence of pathogens and the occurrence of diseases vary based on the planting date, Ohio region, and crop. This emphasizes the importance of understanding your field's history.

What’s happening in the field?

At the Northwest location, the second date was planted on May 23^rd (Table 1). At Northwest, our first planting date (May 16^th) for both corn and soybeans were emerged, with corn being further along in growth than the soybeans (Table 2). Last week at the Western location, the first planting date (March 26) reached V6 in corn (Table 2), meaning the growing point is now above ground and sidedress applications will occur soon. Planting date four was planted on May 24^th. At the Wooster location, the fourth date was planted on May 21^st, with optimal planting conditions. While planting date one and two are progressing quickly with the warm weather.

Table 1. The planting date conditions for planting date four at the Western Agriculture Research Station, planting date two at the Northwest Agriculture Research Station, and the third planting date at the Wooster Campus.

Table 2. Weekly weather conditions for each updated planting date at the Western Agriculture Research Station, Northwest Agriculture Research Station, and Wooster Campus, with day of planting, soil, air temperature averages, and Growing Degree Days (GDDS) from May 20 to May 26. Information from CFAES Weather System (https://weather.cfaes.osu.edu/).