With the likelihood of 2018 farm economics again favoring soybean production, soybeans being planted after soybeans could be on the rise this spring.
With consecutive years of soybean production, yield potential declines and the potential need for additional inputs and precautions increases.
“Agronomically, we never like to see beans after beans, but when it gets into your back pocket sometimes we have to do some things differently,” said Mike Earley, Seed Consultants, Inc. agronomist. “We need to make sure to not plant the same variety in the same field back to back. If we get into continuous beans for multiple years we need to do a lot more scouting and chances are we are going to need some fungicide applications because of a lot more disease pressure in the fields.”
In addition to increased potential for soybean issues including Phytophthora, white mold and frogeye leaf spot, more soybeans could also mean more yield loss to soybean cyst nematode (SCN). The silent robber of soybean yields has been on the rise and has been found in over 60% of Ohio soybean fields, according to Ohio State University Extension. SCN yield losses of 25% to 50% can take place with no above ground symptoms.
Of course, the easiest way to combat SCN is crop rotation, but if that is not an option then variety selection becomes increasingly important.
“Almost all of the soybean varieties sold to farmers in Ohio are labeled ‘Resistant to SCN,’ ‘Resistant to SCN Race 3’ or something similar. Most of the time, a variety labeled as SCN-resistant got its resistance from an ancestral soybean line called PI (Plant Introduction) 88788,” wrote Anne Dorrance, Laura Lindsey, Terry Niblack, and Chris Taylor with Ohio State University Extension in the CORN Newsletter. “This source of resistance was considered broad-spectrum, highly durable, and relatively easy to transfer into the new high-yielding varieties via traditional breeding practices, and that’s why most of our soybean varieties have this resistance. Based on data from hundreds of trials in locations throughout the Midwest, varieties that have this source of resistance will yield higher than similar varieties with no resistance even when SCN populations are low.”
Testing for SCN also becomes increasingly important in fields of soybeans planted after soybeans. There are numerous labs that measure the SCN populations, including OSU’s own C. Wayne Ellett Plant and Pest Diagnostic Clinic. The latest fact sheet has contact information for each of these labs and management practices can be found at http://ohioline.osu.edu/ac-fact/pdf/0039.pdf.