The goals of this project were to determine whether planting date affects the necessity of a fungicidal seed treatment in soybeans and to identify the most effective fungicidal seed treatment in early planting situations. In 2019 and 2020, research was conducted at six NC locations (Beaufort (2019 and 2020), Robeson (2020), Rowan (2020), Sampson (2019), and Yadkin (2019) Counties) to answer these questions. We compared three soybean planting dates (late March to early April, mid to late April, and mid-May) across three soybean maturity groups (III, IV, V). We compared four-five fungicidal seed treatments to an untreated control within each planting date and maturity group combination.

A fungicidal seed treatment protected stand at two of the six locations across planting dates and maturity groups; the impact was similar across fungicidal seed treatments. In 2019, the use of a fungicidal seed treatment protected yield (+5.9-6.9 bu/A) across planting date and maturity groups at two locations. There was no impact of fungicidal seed treatment on yield at locations in 2020. Nonetheless, if you broke down the yield protection from the use of a fungicidal seed treatment across the planting dates in both years, there was more protection of both soybean stand and yield at earlier planting dates. It is therefore our recommendation at this time based on this two-year data set that growers planting earlier than Mid-May consider the use of a fungicidal seed treatment to protect soybean stand and yield in fields with a history of seedling disease pressure, as environmental conditions at earlier planting dates can be more conducive
to seedling disease development. Our results indicate that when multi-mode of action fungicidal seed treatments are used, they typically provide similar protection of soybean stand and yield between industry-leading products.