Tuesday, July 23, 2013
ms_frogeye_leaf_spot

Ohio Soybeans: Management of Frogeye Leaf Spot

AgFax.Com - Your Online Ag News Source


Several reports and samples this past week with frogeye leaf spot on leaves in the upper/mid canopy.

You will be able to find pictures and a detailed factsheet of this soybean disease here.

Frogeye leaf spot is a fungal disease that is caused by Cercospora sojina.  This pathogen is typically pretty rare in the northern states, but due to the widespread planting of some highly susceptible varieties and milder winters, we now have more inoculum in the spring.  One of my previous graduate students (Christian Cruz) did the tedious work to examine soybean residue to find the viable conidia (spores).




At the end of the 2012 season, there was quite a bit of frogeye late in the season in our fungicide trials.  At present there is enough there (almost R1) to begin to plan sprays.

There has been another development with this fungus that is a bit troubling.  Numerous populations of this pathogen have been identified that are resistant to azoxystrobin (Quadris) and pyraclostrobin (Headline).  These were first found in Kentucky in 2010 and since then have also been found in states up and down the Mississippi.  To date, none have been detected in Ohio, but the truth is we have done very little sampling.

In 2007, we had frogeye develop at two of OARDC Branches on Seed Consultants line SC 9384, a susceptible line that they have very generously donated to our field studies.   Disease levels in the top canopy at the end of the season were 28.5% and 47% at Northwest (Wood County) and Western (Clark county) Branch research stations.  The disease was only present in the top canopy at Hotyeville, so fungicide applications were made at the R5, but had very little impact if any. There were no yield differences.

Western had a different story.  At this location, the mid canopy foliage also was more than 40% of the leaf area affected and yield loss was approximately 19% when the best fungicide treated plots (65 to 69 bu/A) were compared to the nontreated (Mean 54 bu/A).

Fungicides applied at R1 on these indetermimant soybeans were not significantly different than the nontreated.  I think that this is due to the fact the plant still has a lot of growing to do and the later foliage does contribute to yield.  Some other examples from the trial include:

Another thing is that rate of the fungicide makes a difference.  For example Evito at 3.1 fl oz yielded 59 bu/A while Evito at 5.7 fl oz (both R3 only applications) yielded 65.9 bu/A.

Domark  (3 fl oz/A) at R3 followed by Domark (3 fl oz/A) at R5) yield 64.9 bu/A while Domark plus Headline (3 fl oz/A) and again at R5 only yield 67.7 bu/A.

There are several things to learn from this study:

  1. If the strobilurins are effective, use them at the higher rates.  This will diminish the chances of fungicide resistance developing in the population.
  2. The triazoles are equally effective, if applied at the right rates and timings.
  3. Through the management of many, many pathogens with fungicides, it is always best to rotate classes of chemistries rather than combining them.  The only reason to combine chemistries is if you have multiple pathogens to control and you need more than one active ingredient in the tank.

Finally – the best approach to managing this disease though is to use a resistant variety; they are the same price as the susceptible and you won’t have to worry about this.


Tags: , , , , , ,


Leave a Reply

Name and Email Address are required fields. Your email will not be published or shared with third parties.

Sunbelt Ag News

    Ohio: Beck’s Hybrids Building New Research and Meeting Facility9-22

    Iowa: Cropland Values Fell in Recent Realtor Survey9-22

    Herbicide Resistance: Enlist Corn and Soybean Traits Approved9-22

    Grain TV: 2015 Acreage Forecast Drives Soybeans Lower9-22

    Doane Cotton Close: More Bearish News from China9-22

    Crop Progress: Corn Harvest at 7%, Soybeans 3%, Cotton 8% — DTN9-22

    DTN Livestock Close: Futures Mixed, Mostly Higher9-22

    DTN Cotton Close: Posts New Low Close in December9-22

    Bayer Will Focus on CropScience and Healthcare – Release MaterialScience9-22

    DTN Grain Close: Soybeans Fall To New Lows; Harvest Gets Closer9-22

    Peanuts: Salmonella Trial Results in Federal Convictions – AgFax9-22

    DTN Livestock Midday: October Hog Futures Surge Higher9-22

    Real Estate Investment Trusts for Agriculture Now Available — DTN9-22

    Good on Grain: Monitoring Corn and Soybean Consumption9-22

    Legislation Expanding STB’s Rail Authority Moves Forward — DTN9-22

    DTN Grain Midday: Trade Lower Across Board9-22

    Mississippi: MSU Researchers Study Soil-Testing Procedures9-22

    DTN Cotton Open: Falls to Steep Losses on Hefty Volume9-22

    DTN Livestock Open: Cattle Futures Set for Moderate Gains9-22

    DTN Grain Open: Soybeans Crumble, Wheat Starts Higher9-22

    Flint on Crops: Wheat Deserves More Attention9-22

    Keith Good: Ethanol Industry Enjoys Big Year, but Uncertainties Linger9-22

    Peanut Harvest: More Digging In SE; Western Growers Gearing Up – AgFax9-20

    Southern Soybeans – Tough, Late-Season Insect Decisions – AgFax9-20

    Rose on Cotton: Bears in the Woods; World Production Could Climb9-19

    Nebraska: Multiple Herbicide-Resistant Weeds and Challenges Ahead9-19

    Cotton Harvest – Midsouth – Picking, Cotton Defoliation Gear Up – AgFax9-19

    Cleveland on Cotton: Market is Dog Paddling; China Offers a Bone9-19

    Texas Rice: Weevil Loves to Eat Hemp Sesbania9-19

    U.S. Rice Growers Have a Market Opportunity in North Africa9-19

    Juggling the Soybean Harvest: Making the Best Decisions on When to Start – DTN9-19

    Rice Crop: Texas, Louisiana Harvests Wrap Up, Rains Slow Progress in Delta9-19

    Rice Market: Short Side Dangerous, Long a Test of Patience9-19

    AFB Grain-Soybean Close: Sell Off Continues9-19

    AFB Cotton Close: Dec. Violate Trendline Support9-19

    AFB Rice Close: Ends Week on Positive Note9-19

    Welch on Wheat: 74% of Spring Crop Harvested9-19

    Welch on Grain: No Change to Corn Condition Ratings9-19

    USDA: Peanut Price Highlights9-19

    Cotton Harvest – Southeast – Pickers Running – AgFax9-19

    DTN Dried Distillers Grain: Prices Moving Downward Again9-19

    DTN Crop Tech: NASA to Launch Soil-Moisture Satellite9-19

    California Cotton Defoliation – Gearing Up Early – AgFax9-19

    Georgia Soybeans: Kudzu Bug Numbers Much Lower This Season9-19

    Most Farmers Willing to Take More Steps to Improve Water Quality, Says Study9-18

    Corn: Nutrient Balance More Important Than Increasing Nitrogen9-18

    Arkansas Woman Joins Husband with 2nd Consecutive 100 BPA Soybeans9-18

    Chumrau on Wheat: Huge Corn, Soy Harvests Will Test Grain Supply Chain9-18

    Keeping Your Cover Crops Legal — DTN9-18

    U.S. Grain Transportation: Miss. River at St. Louis Unusually High9-18

    Corn: Be Wary of Potential Storage Issues — DTN9-18

    Wheat: Producers Urged to Keep Eye on Black Sea Countries’ Markets9-18

    Updating ARC-CO and PLC Payment Indicator for 2014 Crop Year9-18

    U.S. Drought Outlook: Improvements in Texas, Southwest9-18

    Harvest Approaches in Iowa; Time for More Planting in Florida — DTN9-18

    U.S. Energy: Shale-Focused Companies’ Financial Performance Improves9-18

    Gasoline Prices: Average Falls 5 Cents9-18

    Propane Stocks: Rise by 1.4M Barrels9-18

    Diesel Prices: Decrease by a Penny9-18

    Soybeans, Corn in Midwest: Heavy Rain, Early Frost, Slow Going – AgFax9-17

    Farmers First Line of Defense in Keeping GMOs Out of Export Shipments – DTN9-17

    Ohio: 7 Counties Declared Natural Disaster Areas9-17

    California: 42 Counties Designated Natural Disaster Areas9-17

    Hearing Reflects Highly Politicized Debate Over Biotech Crops — DTN9-17

    DTN Fertilizer Trends: Rabobank Forecasts Higher 3Q Retail Prices9-17

    Cotton in Southwest: Need More Heat; 4-Bale Dryland; Pigweed Plans – AgFax9-17

    Sunbelt Ag Events

     

    About Us

    AgFax.Com covers agricultural trends and production topics, with an emphasis on news about cotton, rice, peanuts, corn, soybeans, wheat and tree crops, including almonds, pecans, walnuts and pistachios.

      

    This site also serves as the on-line presence of electronic crop and pest reports published by AgFax Media LLC (formerly Looking South Communications).

        

    Click here to subscribe to our free reports.

      

    We provide early warnings and confirmations about pests, diseases and other factors that influence yield. Our goal is to quickly provide farmers and crop advisors with information needed to make better and more profitable decisions.

         

    Our free weekly crop and pest advisories include:

    • AgFax Midsouth Cotton, covering cotton production and news in Alabama, Arkansas, Louisiana, Mississippi, Tennessee and Missouri.

    • AgFax Southeast Cotton, covering cotton production and news in Alabama, Florida, Georgia, North Carolina, South Carolina and Virginia.

    • AgFax Southwest Cotton (new for 2013!), covering cotton production and news in Texas, Oklahoma, Kansas and New Mexico.

    • AgFax West (formerly MiteFax: SJV Cotton), covering California cotton, alfalfa, tomatoes and other non-permanent crops in California's Central Valley.

    • AgFax Rice covering rice production and news in Arkansas, Louisiana, Mississippi, Missouri and Texas.

    • AgFax Peanuts, covering peanut production in Alabama, Arkansas, Florida, Georgia, Louisiana, Mississippi, North Carolina, South Carolina, Texas and Virginia.

    • AgFax Southern Grain: covering soybeans, corn, milo and small grains in Southern states.

    • AgFax Almonds, covering almonds, pistachios, walnuts and other tree crops in California's Central Valley.

    • AgCom 101, providing guidance to ag professionals involved in social media.

    Our newsletters are sponsored by the following companies: FMC Corporation Chemtura Dow AgroSciences.

          

    Mission statement:

    Make it as easy as possible for our community of readers to find and/or receive needed information.

              

    Contact Information:

    AgFax Media. LLC

    142 Westlake Drive Brandon, MS 39047

    601-992-9488 Office 601-992-3503 Fax

    Owen Taylor Debra L. Ferguson Laurie Courtney

          

    Circulation Questions?

    Contact Laurie Courtney