Taking time to sample soil and have it tested for soybean cyst nematode in fields that will be planted to soybeans in 2016 is worth the time and has the potential to save you money in avoidable yield loss. “And since we are heading into the cropping season, it makes sense that attention be given to those fields in which soybeans will be grown in 2016,” says Greg Tylka, Iowa State University Extension nematologist and plant pathologist. When choosing whether to sample or not, Tylka says you should ask yourself these questions:
1) Have those fields ever been sampled for SCN? If not, now would be a great time.
2) If the fields were sampled in the past, how long has it been?
3) In fields that are known to be infested with SCN, what are the population densities of this pest? Is your management plan keeping your SCN numbers in check?
“The answers to these questions can be worth $100 or more per acre in avoidable soybean yield loss,” says Tylka.
Spring soil sampling guidelines for SCN
•Multiple soil cores (20 cores from every 20 acres or so) should be collected from the upper 8 inches of soil.
•The more soil cores collected and the smaller the area sampled, the more accurate the results will be.
•Do not collect samples when the fields are muddy.
PLAN YOUR SAMPLING: These are the areas of a field where soybean cyst nematode is more likely to be found for the first time.
•One approach to sampling fields in which SCN has not been discovered is to collect soil cores from high-risk areas where SCN may be first found. These areas include high pH spots, low spots, and near fence lines and other places where soil from other fields may have been introduced (see figure below).
•Samples can be sent to several private soil-testing labs in Iowa or surrounding states or to the Iowa State University Plant and Insect Diagnostic Clinic, room 327 Bessey Hall, 2200 Osborn Drive, Ames, IA 50011. The SCN sample submission form for the ISU Clinic is available online.
Management recommendations to combat SCN
Managing SCN is best accomplished by using an integrated approach of growing a diversity of SCN-resistant soybean varieties in rotation with the non-host crop corn and using nematode-protectant seed treatments when soybeans are grown.