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

    U.S. Rice: Planting Decisions Stalled; Alternative Crops Considered1-30

    AgFax Cotton Review: Harvest a Mixed Bag for Texas Growers; India Sells Off Stockpiles1-30

    Rice Market World: Prices Low – But More Positives Than Negatvies1-30

    AgFax Grain Review: Neonics Use Critical; Soybean Prices to Drop, Corn May Rally1-30

    Peanuts: Bankrupt Texoma Sells Mississippi Buy, Dry Facility1-30

    Florida Peanuts: Done Right, Rotation Adds Thousands Of Pounds1-30

    Grain TV: Soybean Year-to-Date Exports Lower than 20141-30

    Cleveland on Cotton: World Consumption Increases; Will U.S. Sell Out?1-30

    Rose on Cotton: Demand is Hot; Anticipate a Pre-Plant Rally1-30

    Biofuel Industry Threatened with Shutdown – DTN1-30

    DTN Livestock Close: Positive Day for Cattle1-30

    Welch on Wheat: Texas Conditions Decline, Still Above Average1-30

    Doane Cotton Close: Strong Exports Don’t Provide Strong Support1-30

    AFB Grain-Soybean Close: General Weakness Continues1-30

    AFB Cotton Close: Narrow Trade Ends Lower1-30

    AFB Rice Close: Hard Sell Off1-30

    Harvard Farm Boy to Show Fellow Students Real Farmers – DTN1-30

    Welch on Grain: Corn, Sorghum Continue to See Strong Exports1-30

    DTN Cotton Close: Tight Trade Ends at Midrange1-30

    2015 Is International Year of the Soils – Video1-30

    Catfish Production Acres Declined 10%1-30

    USDA: Peanut Price Highlights1-30

    DTN Grain Close: Late Corn Rally1-30

    Weekly Cotton Market Review1-30

    DTN Livestock Midday: Cattle Futures Bounce Higher1-30

    DTN Grain Midday: Corn, Soybeans Lead Drop1-30

    Farm Management: 3 Reasons to Praise A Job Well Done – DTN1-30

    Farming: Leaner Profits Drive Farm Loans – Not Equipment Purchases1-30

    Ethanol Remains Competitive as Gasoline Blend Despite Price1-30

    DTN Cotton Open: Futures Start off Lower1-30

    DTN Livestock Open: Aggressive Pressure to Continue1-30

    Bt Corn Hybrid Manufacturers May Face New EPA Rules1-30

    DTN Grain Open: Trade Begins Quietly Higher1-30

    Georgia Cotton: Glyphosate-Resistant Pigweed Fight Requires Vigilance1-30

    Keith Good: $4.8 Billion Hit to Farm Program Possible Over 10 Years1-30

    Mississippi River Locks – ‘Held Together with Baling Wire and Duct Tape’ – DTN1-29

    Senate Passes Keystone Bill, Unable to Get Supermajority – DTN1-29

    ELS Cotton Competitive Payment Rate Is Zero1-29

    California: New Robotic Weeder to Save Time, Money1-29

    Peanut Stocks: Utilization Up 6% from Last Year1-29

    U.S. Grain Transportation: Corn Inspections Highest Since October1-29

    North Carolina: Cotton Variety Performance Data Available1-29

    Texas Pecans: Trade Slow as Harvest Winds Down1-29

    Western Region Pecans: Light Deliveries, Harvest Nearly Done1-29

    U.S. Energy: Market Balances Seen in Changing Futures Price Spreads1-29

    Gasoline Prices: Average Declines Again1-29

    Propane Stocks: Down 1.9M Barrels1-29

    Diesel Prices: Average Drops 7 Cents1-29

    North Carolina: Feb. 4 Meeting Looks At Crop Mix, Marketing Decisions For 20151-28

    Biodiesel: Policy Incentives Necessary for Profitability1-28

    AgFax Peanut Review: Peanut Protein Cure for Nut Allergy?1-28

    DTN Fertilizer Trends: Fewer Pre-Purchases Than Normal1-28

    Ag Lenders’ Sentiment – Latest National Survey From K-State – (Audio)1-28

    Drones – The Next Big Tool in Agriculture1-28

    AgFax Rice Review: Govt. Action Requested Over Iraq Trade; Japan May Increase U.S. Imports1-28

    Seramas: Little Chickens With Great Personality1-28

    Ag Fuel Costs Likely to Dip, Chemicals to Rise in 2015 — DTN1-28

    Seed Companies Expected to Hold Line on Price Increases — DTN1-28

    Soybeans: Higher Protein Levels Mean Better Quality, Better Prices – DTN1-27

    Crop Insurance: Most Corn Farmers Opting for PLC – DTN1-27

    Soybean Rust Turns Up In Louisiana On Kudzu1-27

    Florida: AgSave Summit Meetings, Feb. 231-27

    Crop Insurance: Difference in Expected Program Payments1-27

    Wild Hogs: North Carolina Hunter Scores Record Kill1-27

    Soybeans: East Coast Winter Weather Is No Match for Biodiesel1-27

    Cotton: Industry Recognizes Utah Researcher For Cotton Genome Efforts1-27

    Corn and Soybean Market: Consumption is the Story1-27

    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