A New Cultural Control Alternative for Seedcorn Maggot (SCM) in New York State Field Crop Production
Managing Seedcorn Maggot
Seedcorn Maggot: A Soil-Borne Pest of Early Season Crops in New York
Seedcorn maggot (SCM), Delia platura (Meigen), is a soil-borne, early season pest of corn, soybean and other New York field crops of economic importance. It is especially concerning to producers because there are no rescue options once seed damage occurs. SCM larvae feed directly on ungerminated seeds in the soil, as well as young seedlings. Two to four generations occur annually, depending on environmental conditions, but overwinter exclusively as pupae in the ground. The peak adult emergence from overwintering pupae in early spring is most relevant for crop protection because adults lay eggs during the time field crops are planted in New York (NYSIPM 2023).
Pest Avoidance as a Viable Management Strategy for Seedcorn Maggot
Once a crop is germinated and reaches a robust life stage, the economic threat posed by SCM is reduced. The short time window of vulnerability—immediately after planting—creates an opportunity to use avoidance as a cultural control practice. The catch to this scenario is that adult SCM emergence from overwintering pupae must be accurately predicted each spring. If this is achieved, pest avoidance becomes a viable management strategy for field crop producers. For this specific reason, New York State Integrated Pest Management (NYSIPM) is partnering with the Poveda Lab (Poveda 2023) in the Department of Entomology at Cornell University to deploy a predictive early season SCM adult emergence model.
NEWA Seedcorn Maggot Model
Using Temperature to Predict SCM Emergence
An early SCM model was quickly launched on Network for Environment and Weather Applications (NEWA) in 2022 using existing published scientific literature from other parts of North America which utilized daily maximum and minimum air temperature to estimate insect-specific development beginning on January 1 (NEWA 2023). The literature suggests SCM development occurs on any day where average temperature exceeds 39 F (the base temperature). SCM growing degree days (GDD) are calculated as the daily difference between the two. For example, 10 GDD accumulate when average daily temperature is 49 F (49 F minus 39 F equals 10 GDD which are unitless). When 457 GDD (base 39 F) accumulate from January 1, adult SCM are predicted to emerge from overwintered pupae in the soil.
Limitations of the Current Model
In 2022, however, the Poveda Lab worked with Cornell Cooperative Extension (CCE) and NYSIPM collaborators statewide to monitor adult emergence from 79 farms. This research demonstrated that the current NEWA model iteration, which is based on published research from other North American regions, is not well-suited for New York growing conditions. Poveda lab datasets show adult SCM from overwintered pupae were already present at 25 locations at the time of the first sampling, which was performed during the week of April 23 through 30. This unexpected finding means adult presence is underestimated approximately two to three weeks in most locations throughout New York, which is not adequate.
Addressing the Knowledge Gap
In 2023, the Poveda lab will again lead efforts to conduct a statewide survey of adult SCM emergence from overwintering pupae. This time, sampling will begin the first week of March using the same effective collection methods employed in 2022—yellow and blue sticky cards placed at the edge of corn fields which are managed and replaced weekly by CCE and NYSIPM collaborators (Figure 1). Entomologists from the Poveda lab will continue evaluating the sticky cards and identifying adult SCM catches (Figure 2). When researchers have both an accurate and precise understanding of adult SCM spring emergence in all New York State production regions in 2023, a new research-driven model designed specifically for the Empire State’s field crop production systems will be quickly integrated with the NEWA platform.
Network for Environment and Weather Applications. 2023. Seedcorn Maggot Model. Accessed 17 February 2023.
New York State Integrated Pest Management. 2023. Alternative Seedcorn Maggot Research. Accessed 17 February 2023. .
Poveda, K and Olaya-Arenas, P. 2023. Agroecology of Plant-Insect Interactions. Accessed 17 February 2023.