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

    Rice: Rain Delays Continue But Some Fields Actually Going To Flood – AgFax4-25

    Rose on Cotton: We told you. Old Crop is Too Cheap.4-24

    GMOs – Why Some People Lose Reason About The Technology4-24

    Dow’s Enlist Weed Control – How the System Works4-24

    Grain TV: Brazil Trucker Strike Flares Up Slightly4-24

    Rice Progress: Wet Weather Issues, Planting Delays and Flooded Fields4-24

    DTN Livestock Close: Aggressive Short Covering4-24

    Rice Market: Overbearing Carryover Strain Continues4-24

    New Technology: Can it Help You Cut Costs? Consultants Talk About It. – AgFax Midwest Grain4-24

    Southern Corn Crop – Plenty Of Acreage Still In The Sack – AgFax4-24

    AFB Grain-Soybean Close: Weather Pulls the Rug Under Prices4-24

    AFB Cotton Close: Strong Exports a Boon to Prices4-24

    AFB Rice Close: Exports Unable to Spark Buying4-24

    DTN Grain Close: Favorable Weather Easing Concerns4-24

    Monsanto, Pioneer Genetically Modified Traits Approved by EU – DTN4-24

    USDA: Peanut Price Highlights4-24

    China’s Ag Production: More Corn, Wheat, Rice, Cotton, Less Soybeans4-24

    John Deere: Your Tractor But Not Your Software – DTN4-24

    Dried Distillers Grain: Salt Supplements Save Pasture Grass – DTN4-24

    DTN Livestock Midday: Limited Trade Volume4-24

    Texas: Wheat Field Day, Chillicothe, May 134-24

    Weekly Cotton Market Review – USDA4-24

    DTN Grain Midday: Demand Concerns Promote Selling4-24

    DTN Cotton Open: Cash Grower Sales Resume4-24

    FMC Corporation Completes Acquisition of Cheminova4-24

    Indiana: No-Till and Cover Crops – A Farmer’s View – Video4-24

    DTN Livestock Open: Support from Spillover Buying4-24

    DTN Grain Open: Soybeans Fail to Hold Near Session Highs4-24

    USDA Plan to Lower Greenhouse Gases is a ‘Very Big Deal’ – DTN4-23

    Biofuels: Senators Urge for RFS to Continue Industry Growth – DTN4-23

    U.S. Drought Monitor Quick Look Video – AgFax4-23

    ELS Cotton Competitive Payment Rate Is Zero4-23

    DTN Cotton Close: Strong Exports, Heavy Trade4-23

    Chumrau on Wheat: Competitive Factors Pressuring U.S. Export Pace4-23

    Moving Grains: Barge Rates Down on Improving River Conditions4-23

    U.S. Drought Monitor: Strong Rains in Southeast, Great Plains4-23

    Good on Grain: Spring Wheat Yield Expectations – What Does History Teach Us?4-23

    Alfalfa: From Bone Dry to Fairly Decent Moisture – DTN4-23

    Cutworm Moths on the Move, Don’t Bet on BT Hybrids or Seed Treatments – DTN4-23

    California Oat Hay: Barley Yellow Dwarf Virus Hits Hard, Some Varieties More Tolerant4-23

    Bird Flu: Poultry Produces Watch for Symptoms, CDC Says – DTN4-23

    Irrigation Systems: Are All Your Systems Go?4-23

    Grain TV: Traders Eye Cold Weather in the Midwest4-22

    Residential Propane, Heating Oil: Inventories Increase4-22

    Diesel: Prices Increase Across U.S.4-22

    Gasoline: Average Price Up from Last Week4-22

    U.S. Energy: May Tight Oil Production Expected to be Lower than April’s4-22

    Weed Management: A Regional Approach – Farmdoc4-22

    3 Things to Know About the Current Highly Pathogenic Bird Flu Outbreaks – USDA4-22

    Utah: 2 Counties Declared Natural Disaster Areas Due to Drought – USDA4-22

    Oregon: 4 Counties Declared Natural Disaster Areas Due to Drought – USDA4-22

    USDA’s Hands Tied on Cuban Trade Promotion – DTN4-22

    Soybeans: 5 Million Bushles Ending Stocks Not Helping Prices – Rabobank4-22

    Tree Nuts: U.S. Exports to China Are Down, Prices Remain High – Rabobank4-22

    Corn Market: Next Big Price Factor is Spring Planting – Rabobank4-22

    Fertilizer Market: Prices Decline; Growers Using Less to Do More – Rabobank4-22

    Rice Market: CA Growers Expect Water Cuts; Southern Acreage May Increase – Rabobank4-22

    Cotton Market: Neutral on Old Crop, Bullish New Crop – Rabobank4-22

    Pest Management: 9 Facts Concerning Black Cutworms Popping Up in the Midwest4-22

    Indiana and Nebraska: Weather Challenges are Like Water Off a Duck’s Back to Seasoned Farmers – DTN4-22

    Wheat: Efficacy of Fungicides, Timing Matters4-22

    Herbicide Resistance: Tank Mixing the Key to Control – DTN4-21

    Illinois Corn: Projected Revenues for 2015 – Farmdoc4-21

    Soil Health: Testing Ideas – Are They Worth the Money? – DTN4-21

    Sweet Potatoes Could be an Example of Natural GMOs4-21

    Drought: New Stress Detecting Sensors Help Manage Water Use4-21

    Kentucky: Cover Crop Burndown Tips; Worms and Weevils on the Rise4-21

    USDA: Weekly National Peanut Prices4-21

    Herbicide Resistance: Slowing Weed Evolution with Management Practices4-21

    Grain Sales Direct To Buyer? AgriCharts Rolls Out A Platform.4-21

    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

    Owen Taylor Debra L. Ferguson Laurie Courtney

          

    Circulation Questions?

    Contact Laurie Courtney +