By Anne Dorrance, Ohio State University Extension plant pathologist
As we continue to wait another week for the fields to dry out, this provides some time to sample soil for the soybean cyst nematode (SCN) populations. The SCN Coalition theme for the next few years is “What’s your number?” Do you know where SCN is in your fields and what the current population is sitting at? If its high, then there is a second number: what is the SCN type? This addresses the bigger concern: can it reproduce on the SCN resistance source PI 88788 or Peking? All of these numbers can impact management of this root pathogen and future losses.
In Ohio, we know that the state is now “polluted” with SCN. Fortunately most of those fields are at very low levels, which is where they should be kept.
From samples received to date as part of an initial survey for Ohio of 33 counties as part of the SCN Coalition sampling, we found the following results. Our first round of data collection is from members of the American Soybean Association sponsored by Ohio Soybean Council.
However, there are some surprising locations where individual fields are getting or have gotten into trouble with very high populations (>5,000). So let’s review the loss levels for SCN.
- Not detected: this is not surprising. Remember that SCN sits in pockets and can be quite variable. Continue to monitor your fields.
- Trace: May begin to measure some yield loss on susceptible varieties, especially on lighter soils.
- Low: Plant SCN resistant varieties or rotate to a non-host crop (corn or wheat).
- Moderate: Rotate to a non-host crop and follow with SCN resistant varieties the following year. We have planted susceptible varieties in fields with this level of SCN and have recorded 20% to 50% yield loss.
- High: rotate to a non-host crop for two to three years, then sample SCN to determine if populations have declined to a level where soybeans can be planted again.
SCN is picky about what it feeds and reproduces on but it does like a few weed hosts and
cover crops as well as soybean. If you have SCN in your fields it is important to also control winter annuals such as purple deadnettle, but also avoid cover crops such as several of the clovers, cowpea, common vetch, and hairy vetch.
We recommend sampling in the fall because in most cases this is what the population will be in the spring. With the warmer weather this year and hopefully no frozen ground, there should be ample time to collect and process the samples for spring planting. Processing of samples does cost time and money, so here are a few thoughts on how to sample or how to target your sampling to get the best information for your money.
Updated information on where to send the samples for processing for a fee:
OSU C. Wayne Ellett Plant and Pest Diagnostic Clinic
8995 E. Main St. Bldg 23
Reynoldsburg, OH 43068
www.ppdc.osu.edu – follow this link to download forms to go along with the samples
Brookside Laboratory Inc.
200 White Mountain Dr.
New Bremen, OH 45869
Spectrum Analytic Inc.
1087 Jamison Rd. NW
Washington Court House, OH 43160
For some additional information on Management of SCN always check Ohio’s SCN fact sheet and several other resources as well including: https://u.osu.edu/ohscn/,