PLANTING SOYBEANS BACK-TO-BACK MAY HAVE ECONOMIC AND AGRONOMIC IMPACTS.
Planting soybeans back-to-back may seem like an ideal way to cut costs in light of heightened input costs and fertilizer shortages, but planting in soybean cyst nematode (SCN) infested fields could have economic and agronomic impacts.
“SCN reproduction is greater in hot, dry growing seasons, and many soil samples collected at harvest from field experiments in Iowa in 2021 have very high end-of-season SCN population densities,” said Iowa State University nematologist Greg Tylka in a news release from the SCN Coalition. “Planting an SCN-resistant variety is a soybean grower’s first line of defense. But in many fields, SCN has become resistant to the resistance because the same source of SCN resistance, known as PI 88788, has been used in about 95% of SCN-resistant soybean varieties for decades.”
A recent University of Wisconsin (UW) study found a traditional corn and soybean rotation provided higher yields than planting either crop back-to-back. The study also found higher densities of SCN in fields with consecutive soybean crops.
“The negative effect of SCN on soybean yields is well documented, and protection against SCN is critical to maintain top-end soybean yield potential,” said Shawn Conley, one of the authors of the research, in the news release.
SCN causes damage below the soil surface while plants continue to look healthy. Soil testing before planting or after harvest can help producers manage pest populations.
“If you planted soybeans in 2021, the odds are high that SCN was present in that field,” said Carl Bradley, a University of Kentucky plant pathologist, in the news release. “If soybeans are grown in 2022, SCN population densities will rise, resulting in a larger yield impact. That’s why The SCN Coalition recommends rotating to a non-host crop like corn or wheat.”
The SCN Coalition experts also recommend rotating SCN-resistant soybean varieties, such as Peking or PI 89772.
Nematode-protectant seed treatments can help control SCN numbers early in the season.
“One reason to consider a seed treatment, especially if you are planting soybeans back-to-back, is to control nematodes early in the season,” said Kaitlyn Bissonnette, a University of Missouri plant pathologist, in the news release. “Seed treatments can have an impact on any of three juvenile stages: the unhatched juvenile, the hatching juvenile and the penetrating juvenile.”