Lots of news about Soybean cyst nematode at Commodity Classic a couple of weeks ago. We have continued support to run assays and education sessions for farmers throughout the region to be able to answer “What’s your number?”
There are fields throughout the Midwest, where not only are SCN numbers creeping up to economic levels but also the reproduction factor, which is the ability to reproduce on the one source of resistance (PI 88788) is also creeping up. The good news is that adaptation to the PI 88788 type of resistance towards SCN in soybean is going to be slow – but it is happening in a couple of fields in Ohio where the number of cysts are up to 27% of the susceptible check.
We received soil samples from 238 fields during 2018 – here is the breakdown.
|SCN Population Level||Total fields||% of total|
|High (5000 +)||22||4.6|
The highest counts to date are approximately 15,000 eggs per 100 cc of soil.
So here is the challenge – we are missing samples from some regions of Ohio and definitely could use some more soil samples from all counties. Here is the breakdown by county.
|County||# Fields sampled||County||# Fields sampled||County||# Fields sampled|
AgFax Weed Solutions
Once the samples are processed, those with >500 eggs per 100cc are then added to the pipeline to evaluate for which source of resistance is effective towards that population: PI 88788 or Peking. This will help first, the farmer to know what type of seed to buy and second companies to make decisions on what type of SCN resistant trait to target for Ohio soils. So help us have the best data set in the US by sampling today.
How to sample – there are lots of you tube videos on this from my extension colleagues throughout the region, and Ohio State is no exception. One of our former Ph.D. students, who earned his degree studying soybean cyst nematode produced this piece:
And here are my specific suggestions of where to sample to find SCN:
- Review the yield maps and target those areas of the field where yields were low and you can’t explain why. No flooding or weed outbreak.
- Target fields with heavy purple dead nettle or other winter annuals that can SCN can reproduce on, especially during a warm winter.
- Target fields that are planted continuously to soybean or those where rotations are rare. Don’t forget double crop situations in these fields. For full season soybeans, we can have 3 to 4 life cycles per growing season depending on where your fields are in the state, with double crop soybean, there is time for at least 2 life cycles, thus almost negating the effect of planting a non-host, where the populations can drop by 50%.
Members of the American soybean Association were sent sample bags last May. And if you are like me, it is probably still on your desk, so please take a look for that. If you are not a member, let your county educator know – we will be shipping bags to each county educator in the next few weeks.