Field history is key
Soybean varieties are said to have offensive or defensive traits. Offensive traits are about producing big yields — characteristics like rapid leaf formation, quick leaf expansion, a long-lasting canopy, and the ability to capture or efficiently use water, nutrients and sunlight. Defensive traits are those that confer resistance to key pests and stresses, from nematodes to drought.
The key to choosing among offensive and defensive traits is a thorough understanding of the field’s conditions and history. Among the most important historical notes is the field’s disease history.
“Growers should make sure the variety they select has the right resistance package for their field, because soybean diseases can severely reduce yields,” says Anne Dorrance, Extension soybean expert at Ohio State University.
Other variables can also dramatically influence the success of specific varieties in your field, including:
- Tillage system. Soils in no-till fields can be cooler at planting, and may harbor higher levels of pathogens.
- Planting date. Soybean yield champion Kip Cullers in Purdy, Mo., points out that he plants taller, more drought-resistant varieties as double-crop beans to make the most of scarce resources between July and harvest.
- Soil pH. Acidic soils can tie up calcium, molybdenum and magnesium, according to sources at Asgrow, and increase the risk of herbicide carryover from imidazolinone herbicides. High soil pH can reduce the availability of iron, manganese, boron, copper and zinc, and increase the chances of sulfonylurea herbicide carryover.
- Plant characteristics. Where diseases like white mold may be a problem, consider not only resistant genes, but also plants that are shorter and less bushy to reduce the environment that favors the pathogen.