C.O.R.N. Newsletter 2010-41

Dates Covered: 
December 21, 2010 - January 12, 2011
Editor: 
Greg LaBarge
Insect Resistance Management (IRM) CalculatorInsect Resistance Management (IRM) Calculator

Insect Resistance Management (IRM) Calculator

The National Corn Growers Association has developed a calculator that helps growers determine how much refuge is required for the various Bt transgenic corn hybrids used for insect control.  The calculator is intended to illustrate the appropriate refuge calculation, the quantity of standard seed bags to purchase for both trait and refuge, and possible planting configurations for planting certain corn products.   The calculator is available at http://www.irmcalculator.com/irmcalculator/irmcalculator/index.html.  You can download the calculator from this site to both PC and Mac platforms.  However, as this site states, the calculator does not replace or supplement the applicable manufacturer's IRM Grower Guide in any way.  As a grower using this information, you are still obligated to understand and abide by the applicable IRM Grower Guide on planting and Insect Resistance Management.  But the calculator is very good in helping you better understand refuge requirements for all of the various transgenic products.

Impact of SCN Resistance on SCN Pressure and Soybean YieldImpact of SCN Resistance on SCN Pressure and Soybean Yield

Impact of SCN Resistance on SCN Pressure and Soybean Yield

As part of a multi-state, 3-year North Central Soybean Research Program project, we have compared the changes in SCN populations under varieties which are susceptible or have resistance derived from PI 88788, Peking, or PI437654 (CystX).  Management of soybean cyst nematode consists primarily of crop rotation both with non-hosts and with different sources of resistance (if they are available).

Best SCN Management Strategies for Ohio Soybean Producers

Egg counts/200 cc of soil

Cyst Count

Population Level

Management Strategies

0-40

 

0

None detected

Continue to monitor field after two crops of soybean

40-200

1

Trace

Begin to measure some yield loss in Susceptible varieties at or above 200 eggs/200cc

200-2000

1-4

Low

Plant SCN resistant variety or rotate to a non-host crop.  At or above 2000 eggs some yield loss may occur on SCN resistant varieties

2000-5000

3-20

Moderate

Rotate to a non-host crop next year and return with SCN resistant soybeans the following year. 

5000 and over

15-20 and higher

High

Rotate to a non-host crop for two to three years then sample the soil to determine nematode populations before planting SCN resistant varieties

 

This study was planted in 9 locations over the past 3 years, each with a different initial SCN population.  At each location, five soybean varieties were planted in randomized block design with four replications.  Each variety strip was sampled within a few days of planting in the spring and again after harvest.  For each strip, 6 to 10 subsamples were collected.  The average egg counts are the mean of the subsamples.  On average there were 200 SCN samples collected from each location at each sampling. The yields from each strip were collected by the producer/educator cooperator and adjusted to 13.5% moisture.  

The table below has the yields for each of the different varieties derived from the different sources of SCN resistance.

Type of resistance

San08

Put08

San09

Put09

She09

Put10

Pik10

Ros10

San10

Susceptible

24.3

42.3

47.0

62.7

53.2

69.6

71.1

57.1

44.8

PI88788-1

48.8

38.5

56.4

65.9

55.9

73.3

64.1

64.2

41.1

PI88799-2

37.0

43.5

47.3

61.9

53.3

66.7

69.6

66.1

42.9

Peking

45.5

42.7

59.9

62.4

52.8

67.1

57.2

56.3

47.4

PI43765 (CystX

42.0

33.0

47.3

56.8

53.2

71.2

58.1

51.5

39.1

Mean

39.5

39.9

51.6

61.9

53.6

69.6

64.0

59.0

43.0

P value

***

***

***

**

ns

ns

***

***

Ns

Spring SCN

3089

471

373

7

28

150

5

68

1

*** indicates that P value was <0.001

** indicates P value was <0.01

* indicates P value was <0.05

Note:  Yield difference in 09-Putnam maybe due to Phytophthora partial resistance levels; 10-Ross and 10-Pickaway these yield difference were due to shattering of the earlier lines.

One of the nine locations had significant yield loss (approximately 50%) when SCN populations were greater than 3,000 eggs/cup of soil.  When SCN populations were 200  to 500, yield loss occurred (Sandusky 09) but not in Putnam08.  This may be due to the fact that the Putnam location had a very uneven distribution of SCN in the field.  At this location in the spring, 23% of the subsamples SCN was not detected.  When SCN populations were less than 200, the differences in yield were not significant (ns) or could be attributed to other factors, shattering of early maturing lines, lack of Phytophthora resistance

The SCN populations changed in density under each type of resistance at location, the Sandusky 2009 location was a bit of a “hot-spot” and had dramatic increases in SCN numbers under the susceptible as well as all of the sources of resistance.

Resistant Source

Spring

Fall

fold change

Susceptible

290.1

17508.0

60.4

PI88788

389.2

7829.3

20.1

PI88788

523.9

5752.3

11.0

Peking

220.0

3784.4

17.2

CystX, PI437654

441.8

15244.3

34.5

 The remaining locations, had either an increase (Shelby09, Putnam10) or decline (Putnam08, Sandusky08).

 

Shelby-09

Putnam-08

Sandusky-08

Putnam10

 

Spring

Fall

Spring

Fall

Spring

Fall

Spring

Fall

Susceptible

62

1028

129

1916

3242

9525

57

1382

PI88788

13

193

326

159

3796

2974

142

1018

PI88788

72

274

846

229

2768

2042

213

1254

Peking

0

35

515

165

3212

1450

251

1735

CystX, PI437654

4

21

380

358

2427

1726

87

910

The take-home message from all of this is caution, SCN numbers can increase dramatically when susceptible or even resistant varieties are grown and it is going to be critical to continue to monitor SCN numbers as part of the basic soybean production practice or management program for Ohio.  In most cases when resistant varieties were planted the SCN numbers declined.  However there were several fields where this did not happen.  The higher the SCN numbers, the less likely that egg counts dropped even under the resistant varieties.  Bottom line:  keep the SCN populations low through rotation.

Ohio has evaluated soybean varieties, each with different types of SCN resistance, for the past 3 production seasons.  In addition to documenting the dramatic changes that can occur in SCN populations, other key findings from this study were:

  1. Our original recommendations based on egg counts are correct across the soil types.
  2. Identified SCN populations in which the PI88788 is not as effective as it once was. 
  3. Demonstrated that varieties with SCN resistance yield as well as those with no resistance when SCN populations are <200 eggs/cup of soil
  4. Varieties with SCN resistance out yield susceptible varieties when SCN populations are high.

The highest yield loss recorded in the susceptible variety was close to 50% in the first year of the study when populations were very high.

For additional information about SCN Management, the NCSRP funded Plant Health Initiative has a very nice website including videos with collaborator Greg Tylka (Iowa State University) about soil sampling (http://www.planthealth.info/scn_basics.htm)

For more Ohio information and a listing of labs that do soil analysis for SCN see our factsheet at:  http://www.oardc.ohio-state.edu/ohiofieldcropdisease/soybeans/AC_39_08.pdf

These studies were part of a multi-state project and we are still processing soil and waiting for the HG-type data from our collaborator.  We want to thank the producers that participated in this study, without their outstanding assistance this would not have been possible.

OABA & OSU Crop Production Conference

The annual Ohio Ag Business Association and Ohio State University Crop Production Conference is schedules for January 6 and 7 at the Fawcett Center on The Ohio State University Columbus Campus. The program will have a different format for 2011.  The programs start at 8:50 am each day and conclude by 3:50 pm. Cost is $80 for one day and $150 for both.

On January 6th the morning session will focus on Nutrient Management 3.0 CCA CEUs. The 9:00 a.m. General Session will focus on “Volatility of the Fertilizer Market” with Michael Rahm, Vice President, Market and Strategic Analysis, The Mosaic Company. Participant will then chose from 2 of 3 concurrent sessions. The afternoon session will focus on Soil & Water Management with 3.0 CCA CEUs. The 1:00 p.m. General Session will cover “What Does Water Nutrient Impairment Mean?” with Jeff Reutter, Director, Sea Grant & Stone Lab, The Ohio State University. Concurrent session will fill out the agenda.

January 7th morning session will focus on Crop Management  with 3.0 CCA CEUs. The 9:00 a.m. General Session is “Soybean/Wheat Production - Where We’ve Been & Where We’re Going” with Jim Beuerlein, Prof. Emeritus, Hort. & Env. Science, The Ohio State University. Concurrent sessions complete the morning. The afternoon session General Session topic is 1:00 p.m. General Session “Fungicide Seed Treatments - What Are They Good For?” with Anne Dorrance, Plant Pathology, The Ohio State University. Concurrent session end the day.

Complete registration and agenda information can be found on the Ohio Ag Business Association website or our calendar page https://agcrops.osu.edu/calendar

Agronomy Educational Programs for 2011

A current calendar of agronomy related educational events around the state of Ohio can be found on our calendar page. Many events offer Certified Crop Adviser credits and Pesticide Applicator credits in addition to current information on topics of interest in your area. Many events require pre-registration so refer to this calendar often during the next 3 months for activities in your area or activities in other areas that meet an interest you have.

The calendar can be found at https://agcrops.osu.edu/calendar or contact your local extension office.

January events include:

January 11 
Ohio Pesticide Commercial Applicator Recertification Conferences 2011
Kalahari Conference Center and Resort, Sandusky, Ohio
Recertification opportunity for Ohio Commercial license holders.
 
January 19 
Certified Crop Adviser (CCA) Exam Training Session
Shelby County Extension Office, 810 Fair Road, Shelby, OH
This training session is designed to help participants understand the principles necessary to become a certified crop advisor and to assist in preparation for the state and international CCA exams. It is not a crash course designed to cover all specific information necessary to pass the CCA exam. However, it will cover some of the performance objectives and will assist students by giving better direction for independent study.
 
January 25 
Preserving Corn & Soybean Profits with Agronomy Updates
Crawford County Court House, 112 East Mansfield St., Bucyrus, OH
 
January 27
Corn/Soybean Day
Founder’s Hall at Sauder Village 22611 St. Rt. 2 Archbold, Ohio
Insect to be on the lookout for in 2011, Managing Wheat for Yield and Quality, What is going on with the Weather and What to expect for 2011, and Risk and Reward in Nutrient Management plus CCA and Pesticide Applicator credits.
 
January 27 
Agronomy Night-Putnam County
Kalida K of C Hall. Kalida, OH
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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.