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Corn Newsletter : 2018-38
Sampling for Soybean Cyst Nematode – Fall is the time!Author(s): Anne Dorrance
As we wait another week for the fields to dry out, this provides some time to sample soil for the 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? Which addresses the bigger question 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.
The situation 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. Our first round is from members of the American Soybean Association sponsored by Ohio Soybean Council.
SCN Population Level
High (5000 +)
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 for the majority of soil types here.
Levels of SCN and concerns
SCN egg Count/100 cc
5000 & over
If your SCN report in the past has come back as:
- Not detected: this is not surprising. Remember that SCN sits in pockets and can we quite variable (Figure 1). 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 and common & hairy vetch.
So it is time to sample! 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 should give ample time to collect and process the samples in plenty of time 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: https://u.osu.edu/ohscn/
http://soybeanresearchinfo.com/- link to the 5thedition of the SCN guide developed through the North Central Soybean Research Program.
Link to recent findings and sampling protocol for SCN: https://www.youtube.com/watch?v=FQgg-UPQdcs&feature=youtu.be
2018 Ohio Corn Performance Test Preliminary Results Now Available On-Line
Results from the 2018 Ohio Corn Performance Test are now available on line at: http://oardc.osu.edu/corntrials
Single and multi-year agronomic data is currently available for the Southwest / West Central and North Central / Northeast regions. Upper Sandusky will be harvested when field conditions allow. Results for Upper Sandusky and the Northwest region summary will be updated immediately after harvest. The results can be accessed by following the links on the left side of the page. Information regarding the growing season, evaluation procedures and traits will be available soon. Additional hybrids will be added as soon as marketing information becomes available, as will the combined regional tables (which are especially helpful in assessing hybrid performance across locations).
Variable Rate Corn Seeding Considerations
As producers are planning their seed needs for next year, it is important to think about acreage, hybrids, and seeding rates. Finding the best corn seeding rate is important for efficient production, but the “optimum” corn seeding rate – the one that maximizes profitability – can vary within and among fields with small differences in soils and weather. While adoption of variable rate technology is increasing, there are still questions related to how this technology will impact seeding rates, profitability, and be impacted by yield level compared to using a uniform (or fixed) seeding rate with modern hybrids. In order to help estimate the profitability of variable rate corn seeding in the US Corn Belt, we used results of 93 seeding rate trials in Ohio (2012-2016) to see how variable the response to seeding rates was, and to see if factors like yield level might help us do a better job of setting plant populations.
Eighty percent of the environments showed a quadratic yield response to seeding rate, meaning that most yields were lower at the highest seeding rates compared to medium seeding rates. The economic optimum seeding rate (EOSR) values ranged from 18,000 to 44,340 seeds/acre, with an overall average of 32,129 seeds/acre(Table 1). Yield at the EOSR ranged from 117 to 271 bu/acre (205.5 bu/acre average), which resulted in a return-to-seed (RTS) range of $360 to $900/acre with an average RTS of $673.52/acre. The uniform optimum seeding rate (UOSR) that maximized profitability was 32,721 seeds/acre and 202.6 bu/acre, respectively, with an estimated RTS of $661/acre (Table 1). Overall, the estimated RTS advantage from using the EOSR in each trial was $12.53 ac-1. There was a weak relationship suggesting an increased EOSR with increasing grain yield, but difficulty still exists to pinpoint the best seeding rate to use before the season starts.
Table 1.Average EOSR and UOSR for Ohio trials. The ‘Difference’ column shows the UOSR subtracted from the EOSR values.
Optimum seeding rate (seeds/acre)
Return from yield ($/acre)
Cost of seed ($/acre)
Return to seed ($/acre)
†ns indicates paired t-test P> 0.05, *indicates paired t-test is significant at P< 0.05, and ** indicates significant at P< 0.01.
This data suggests there is potential for modest increases in profitability from optimization of corn seeding rate in environments with a range in yield levels. Predictions of optimal seeding rates within a field and year will need to improve beyond current levels before estimated RTS of this level will be approached. Small changes in seeding rates may be needed to impact profitability, but obtaining this resolution on small spatial scales is a challenge that will need to be addressed in future research. The full fact sheet can be found here: AGF-520 Estimating Return-to-Seed of Variable vs. Uniform Corn Seeding Rates (https://ohioline.osu.edu/factsheet/agf-520).
**Emerson Nafziger was also an author on this article
Communicating With Your Landowner Meeting November 15
All-Ohio Chapter Soil & Water Conservation Society Conference January 18, 2019Author(s): Alan Sundermeier, CCA
“Sharpen the Scalpel – Tools to Identify High-Risk Conservation Needs” will be the theme of the SWCS conference on Friday, January 18, 2019 from 9:00 am to 3:45 pm at the Der Dutchman Restaurant in Plain City, Ohio.
Topics include: Ag Conservation Planning Framework (ACPF), Elevated Phosphorus Management, Watershed application of ACPF, Municipal Partnership for Ecosystem Services.
The public is invited. Register by January 14. Click here for registration flyer ……..
About the C.O.R.N. Newsletter
C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.
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